X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=libringbuffer%2Fring_buffer_frontend.c;h=310e0b93e51a435b74e6d0b9d0c6b4ebc6226abf;hb=4318ae1be57eb7983ab4857a7a8eeb4a030a8216;hp=2b4ecc24b1c44769afe455f40773b6c6db5233c8;hpb=a6352fd40a2090fd883a6c369144bf405c9e9ec4;p=lttng-ust.git

diff --git a/libringbuffer/ring_buffer_frontend.c b/libringbuffer/ring_buffer_frontend.c
index 2b4ecc24..310e0b93 100644
--- a/libringbuffer/ring_buffer_frontend.c
+++ b/libringbuffer/ring_buffer_frontend.c
@@ -39,16 +39,38 @@
  */
 
 #include <sys/types.h>
-#include <sys/shm.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #include <urcu/compiler.h>
 #include <urcu/ref.h>
 
 #include "smp.h"
-#include "config.h"
+#include <lttng/ringbuffer-config.h>
 #include "backend.h"
 #include "frontend.h"
 #include "shm.h"
 
+#ifndef max
+#define max(a, b)	((a) > (b) ? (a) : (b))
+#endif
+
+/*
+ * Use POSIX SHM: shm_open(3) and shm_unlink(3).
+ * close(2) to close the fd returned by shm_open.
+ * shm_unlink releases the shared memory object name.
+ * ftruncate(2) sets the size of the memory object.
+ * mmap/munmap maps the shared memory obj to a virtual address in the
+ * calling proceess (should be done both in libust and consumer).
+ * See shm_overview(7) for details.
+ * Pass file descriptor returned by shm_open(3) to ltt-sessiond through
+ * a UNIX socket.
+ *
+ * Since we don't need to access the object using its name, we can
+ * immediately shm_unlink(3) it, and only keep the handle with its file
+ * descriptor.
+ */
+
 /*
  * Internal structure representing offsets to use at a sub-buffer switch.
  */
@@ -63,18 +85,20 @@ __thread unsigned int lib_ring_buffer_nesting;
 
 static
 void lib_ring_buffer_print_errors(struct channel *chan,
-				  struct lib_ring_buffer *buf, int cpu);
+				  struct lttng_ust_lib_ring_buffer *buf, int cpu,
+				  struct lttng_ust_shm_handle *handle);
 
 /*
  * Must be called under cpu hotplug protection.
  */
-void lib_ring_buffer_free(struct lib_ring_buffer *buf)
+void lib_ring_buffer_free(struct lttng_ust_lib_ring_buffer *buf,
+			  struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
+	struct channel *chan = shmp(handle, buf->backend.chan);
 
-	lib_ring_buffer_print_errors(chan, buf, buf->backend.cpu);
-	free(shmp(buf->commit_hot));
-	free(shmp(buf->commit_cold));
+	lib_ring_buffer_print_errors(chan, buf, buf->backend.cpu, handle);
+	/* buf->commit_hot will be freed by shm teardown */
+	/* buf->commit_cold will be freed by shm teardown */
 
 	lib_ring_buffer_backend_free(&buf->backend);
 }
@@ -88,10 +112,11 @@ void lib_ring_buffer_free(struct lib_ring_buffer *buf)
  * should not be using the iterator concurrently with reset. The previous
  * current iterator record is reset.
  */
-void lib_ring_buffer_reset(struct lib_ring_buffer *buf)
+void lib_ring_buffer_reset(struct lttng_ust_lib_ring_buffer *buf,
+			   struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned int i;
 
 	/*
@@ -100,14 +125,14 @@ void lib_ring_buffer_reset(struct lib_ring_buffer *buf)
 	 */
 	v_set(config, &buf->offset, 0);
 	for (i = 0; i < chan->backend.num_subbuf; i++) {
-		v_set(config, &shmp(buf->commit_hot)[i].cc, 0);
-		v_set(config, &shmp(buf->commit_hot)[i].seq, 0);
-		v_set(config, &shmp(buf->commit_cold)[i].cc_sb, 0);
+		v_set(config, &shmp_index(handle, buf->commit_hot, i)->cc, 0);
+		v_set(config, &shmp_index(handle, buf->commit_hot, i)->seq, 0);
+		v_set(config, &shmp_index(handle, buf->commit_cold, i)->cc_sb, 0);
 	}
 	uatomic_set(&buf->consumed, 0);
 	uatomic_set(&buf->record_disabled, 0);
 	v_set(config, &buf->last_tsc, 0);
-	lib_ring_buffer_backend_reset(&buf->backend);
+	lib_ring_buffer_backend_reset(&buf->backend, handle);
 	/* Don't reset number of active readers */
 	v_set(config, &buf->records_lost_full, 0);
 	v_set(config, &buf->records_lost_wrap, 0);
@@ -142,11 +167,12 @@ void channel_reset(struct channel *chan)
 /*
  * Must be called under cpu hotplug protection.
  */
-int lib_ring_buffer_create(struct lib_ring_buffer *buf,
+int lib_ring_buffer_create(struct lttng_ust_lib_ring_buffer *buf,
 			   struct channel_backend *chanb, int cpu,
-			   struct shm_header *shm_header)
+			   struct lttng_ust_shm_handle *handle,
+			   struct shm_object *shmobj)
 {
-	const struct lib_ring_buffer_config *config = chanb->config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chanb->config;
 	struct channel *chan = caa_container_of(chanb, struct channel, backend);
 	void *priv = chanb->priv;
 	unsigned int num_subbuf;
@@ -159,22 +185,24 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf,
 		return 0;
 
 	ret = lib_ring_buffer_backend_create(&buf->backend, &chan->backend,
-			cpu, shm_header);
+			cpu, handle, shmobj);
 	if (ret)
 		return ret;
 
-	set_shmp(&buf->commit_hot,
-		 zalloc_shm(shm_header,
-			sizeof(*buf->commit_hot) * chan->backend.num_subbuf));
-	if (!shmp(buf->commit_hot)) {
+	align_shm(shmobj, __alignof__(struct commit_counters_hot));
+	set_shmp(buf->commit_hot,
+		 zalloc_shm(shmobj,
+			sizeof(struct commit_counters_hot) * chan->backend.num_subbuf));
+	if (!shmp(handle, buf->commit_hot)) {
 		ret = -ENOMEM;
 		goto free_chanbuf;
 	}
 
-	set_shmp(&buf->commit_cold,
-		 zalloc_shm(shm_header,
-			sizeof(*buf->commit_cold) * chan->backend.num_subbuf));
-	if (!shmp(buf->commit_cold)) {
+	align_shm(shmobj, __alignof__(struct commit_counters_cold));
+	set_shmp(buf->commit_cold,
+		 zalloc_shm(shmobj,
+			sizeof(struct commit_counters_cold) * chan->backend.num_subbuf));
+	if (!shmp(handle, buf->commit_cold)) {
 		ret = -ENOMEM;
 		goto free_commit;
 	}
@@ -188,13 +216,13 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf,
 	 */
 	subbuf_header_size = config->cb.subbuffer_header_size();
 	v_set(config, &buf->offset, subbuf_header_size);
-	subbuffer_id_clear_noref(config, &shmp(buf->backend.buf_wsb)[0].id);
-	tsc = config->cb.ring_buffer_clock_read(shmp(buf->backend.chan));
-	config->cb.buffer_begin(buf, tsc, 0);
-	v_add(config, subbuf_header_size, &shmp(buf->commit_hot)[0].cc);
+	subbuffer_id_clear_noref(config, &shmp_index(handle, buf->backend.buf_wsb, 0)->id);
+	tsc = config->cb.ring_buffer_clock_read(shmp(handle, buf->backend.chan));
+	config->cb.buffer_begin(buf, tsc, 0, handle);
+	v_add(config, subbuf_header_size, &shmp_index(handle, buf->commit_hot, 0)->cc);
 
 	if (config->cb.buffer_create) {
-		ret = config->cb.buffer_create(buf, priv, cpu, chanb->name);
+		ret = config->cb.buffer_create(buf, priv, cpu, chanb->name, handle);
 		if (ret)
 			goto free_init;
 	}
@@ -211,17 +239,18 @@ free_chanbuf:
 	return ret;
 }
 
+#if 0
 static void switch_buffer_timer(unsigned long data)
 {
-	struct lib_ring_buffer *buf = (struct lib_ring_buffer *)data;
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct lttng_ust_lib_ring_buffer *buf = (struct lttng_ust_lib_ring_buffer *)data;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 
 	/*
 	 * Only flush buffers periodically if readers are active.
 	 */
-	if (uatomic_read(&buf->active_readers))
-		lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
+	if (uatomic_read(&buf->active_readers) || uatomic_read(&buf->active_shadow_readers))
+		lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE, handle);
 
 	//TODO timers
 	//if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
@@ -231,11 +260,13 @@ static void switch_buffer_timer(unsigned long data)
 	//	mod_timer(&buf->switch_timer,
 	//		  jiffies + chan->switch_timer_interval);
 }
+#endif //0
 
-static void lib_ring_buffer_start_switch_timer(struct lib_ring_buffer *buf)
+static void lib_ring_buffer_start_switch_timer(struct lttng_ust_lib_ring_buffer *buf,
+			   struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	//const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 
 	if (!chan->switch_timer_interval || buf->switch_timer_enabled)
 		return;
@@ -251,9 +282,10 @@ static void lib_ring_buffer_start_switch_timer(struct lib_ring_buffer *buf)
 	buf->switch_timer_enabled = 1;
 }
 
-static void lib_ring_buffer_stop_switch_timer(struct lib_ring_buffer *buf)
+static void lib_ring_buffer_stop_switch_timer(struct lttng_ust_lib_ring_buffer *buf,
+			   struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
+	struct channel *chan = shmp(handle, buf->backend.chan);
 
 	if (!chan->switch_timer_interval || !buf->switch_timer_enabled)
 		return;
@@ -263,18 +295,19 @@ static void lib_ring_buffer_stop_switch_timer(struct lib_ring_buffer *buf)
 	buf->switch_timer_enabled = 0;
 }
 
+#if 0
 /*
  * Polling timer to check the channels for data.
  */
 static void read_buffer_timer(unsigned long data)
 {
-	struct lib_ring_buffer *buf = (struct lib_ring_buffer *)data;
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct lttng_ust_lib_ring_buffer *buf = (struct lttng_ust_lib_ring_buffer *)data;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 
 	CHAN_WARN_ON(chan, !buf->backend.allocated);
 
-	if (uatomic_read(&buf->active_readers)
+	if (uatomic_read(&buf->active_readers) || uatomic_read(&buf->active_shadow_readers))
 	    && lib_ring_buffer_poll_deliver(config, buf, chan)) {
 		//TODO
 		//wake_up_interruptible(&buf->read_wait);
@@ -289,11 +322,13 @@ static void read_buffer_timer(unsigned long data)
 	//	mod_timer(&buf->read_timer,
 	//		  jiffies + chan->read_timer_interval);
 }
+#endif //0
 
-static void lib_ring_buffer_start_read_timer(struct lib_ring_buffer *buf)
+static void lib_ring_buffer_start_read_timer(struct lttng_ust_lib_ring_buffer *buf,
+			   struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 
 	if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER
 	    || !chan->read_timer_interval
@@ -313,10 +348,11 @@ static void lib_ring_buffer_start_read_timer(struct lib_ring_buffer *buf)
 	buf->read_timer_enabled = 1;
 }
 
-static void lib_ring_buffer_stop_read_timer(struct lib_ring_buffer *buf)
+static void lib_ring_buffer_stop_read_timer(struct lttng_ust_lib_ring_buffer *buf,
+			   struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 
 	if (config->wakeup != RING_BUFFER_WAKEUP_BY_TIMER
 	    || !chan->read_timer_interval
@@ -329,7 +365,7 @@ static void lib_ring_buffer_stop_read_timer(struct lib_ring_buffer *buf)
 	 * do one more check to catch data that has been written in the last
 	 * timer period.
 	 */
-	if (lib_ring_buffer_poll_deliver(config, buf, chan)) {
+	if (lib_ring_buffer_poll_deliver(config, buf, chan, handle)) {
 		//TODO
 		//wake_up_interruptible(&buf->read_wait);
 		//wake_up_interruptible(&chan->read_wait);
@@ -337,31 +373,36 @@ static void lib_ring_buffer_stop_read_timer(struct lib_ring_buffer *buf)
 	buf->read_timer_enabled = 0;
 }
 
-static void channel_unregister_notifiers(struct channel *chan)
+static void channel_unregister_notifiers(struct channel *chan,
+			   struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	int cpu;
 
 	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
 		for_each_possible_cpu(cpu) {
-			struct lib_ring_buffer *buf = &shmp(chan->backend.buf)[cpu];
+			struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[cpu].shmp);
 
-			lib_ring_buffer_stop_switch_timer(buf);
-			lib_ring_buffer_stop_read_timer(buf);
+			lib_ring_buffer_stop_switch_timer(buf, handle);
+			lib_ring_buffer_stop_read_timer(buf, handle);
 		}
 	} else {
-		struct lib_ring_buffer *buf = shmp(chan->backend.buf);
+		struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[0].shmp);
 
-		lib_ring_buffer_stop_switch_timer(buf);
-		lib_ring_buffer_stop_read_timer(buf);
+		lib_ring_buffer_stop_switch_timer(buf, handle);
+		lib_ring_buffer_stop_read_timer(buf, handle);
 	}
-	channel_backend_unregister_notifiers(&chan->backend);
+	//channel_backend_unregister_notifiers(&chan->backend);
 }
 
-static void channel_free(struct channel *chan)
+static void channel_free(struct channel *chan, struct lttng_ust_shm_handle *handle,
+		int shadow)
 {
-	channel_backend_free(&chan->backend);
-	free(chan);
+	if (!shadow)
+		channel_backend_free(&chan->backend, handle);
+	/* chan is freed by shm teardown */
+	shm_object_table_destroy(handle->table);
+	free(handle);
 }
 
 /**
@@ -378,96 +419,64 @@ static void channel_free(struct channel *chan)
  *                         padding to let readers get those sub-buffers.
  *                         Used for live streaming.
  * @read_timer_interval: Time interval (in us) to wake up pending readers.
- * @shmid: shared memory ID (output)
  *
  * Holds cpu hotplug.
  * Returns NULL on failure.
  */
-struct channel *channel_create(const struct lib_ring_buffer_config *config,
+struct lttng_ust_shm_handle *channel_create(const struct lttng_ust_lib_ring_buffer_config *config,
 		   const char *name, void *priv, void *buf_addr,
 		   size_t subbuf_size,
 		   size_t num_subbuf, unsigned int switch_timer_interval,
 		   unsigned int read_timer_interval,
-		   int *shmid)
+		   int *shm_fd, int *wait_fd, uint64_t *memory_map_size)
 {
 	int ret, cpu;
+	size_t shmsize;
 	struct channel *chan;
-	size_t shmsize, bufshmsize;
-	struct shm_header *shm_header;
-	unsigned long num_subbuf_alloc;
+	struct lttng_ust_shm_handle *handle;
+	struct shm_object *shmobj;
+	struct shm_ref *ref;
 
 	if (lib_ring_buffer_check_config(config, switch_timer_interval,
 					 read_timer_interval))
 		return NULL;
 
-	/* Calculate the shm allocation layout */
-	shmsize = sizeof(struct shm_header);
-	shmsize += sizeof(struct channel);
-
-	/* Per-cpu buffer size: control (prior to backend) */
-	bufshmsize = sizeof(struct lib_ring_buffer);
-	shmsize += bufshmsize * num_possible_cpus();
-
-	/* Per-cpu buffer size: backend */
-	/* num_subbuf + 1 is the worse case */
-	num_subbuf_alloc = num_subbuf + 1;
-	bufshmsize = sizeof(struct lib_ring_buffer_backend_pages *) * num_subbuf_alloc;
-	bufshmsize += subbuf_size * (num_subbuf_alloc);
-	bufshmsize += (sizeof(struct lib_ring_buffer_backend_pages) + subbuf_size) * num_subbuf_alloc;
-	bufshmsize += sizeof(struct lib_ring_buffer_backend_subbuffer) * num_subbuf;
-	shmsize += bufshmsize * num_possible_cpus();
-
-	/* Per-cpu buffer size: control (after backend) */
-	bufshmsize += sizeof(struct commit_counters_hot) * num_subbuf;
-	bufshmsize += sizeof(struct commit_counters_cold) * num_subbuf;
-
-	/* Allocate shm */
-	*shmid = shmget(getpid(), shmsize, IPC_CREAT | IPC_EXCL | 0700);
-	if (*shmid < 0) {
-		if (errno == EINVAL)
-			ERR("shmget() returned EINVAL; maybe /proc/sys/kernel/shmmax should be increased.");
-		else
-			PERROR("shmget");
+	handle = zmalloc(sizeof(struct lttng_ust_shm_handle));
+	if (!handle)
 		return NULL;
-	}
-
-	shm_header = shmat(*shmid, NULL, 0);
-	if (shm_header == (void *) -1) {
-		perror("shmat");
-		goto destroy_shmem;
-	}
-
-	/* Already mark the shared memory for destruction. This will occur only
-         * when all users have detached.
-	 */
-	ret = shmctl(*shmid, IPC_RMID, NULL);
-	if (ret == -1) {
-		perror("shmctl");
-		goto destroy_shmem;
-	}
 
-	shm_header->magic = SHM_MAGIC;
-	shm_header->major = SHM_MAJOR;
-	shm_header->major = SHM_MINOR;
-	shm_header->bits_per_long = CAA_BITS_PER_LONG;
-	shm_header->shm_size = shmsize;
-	shm_header->shm_allocated = sizeof(struct shm_header);
+	/* Allocate table for channel + per-cpu buffers */
+	handle->table = shm_object_table_create(1 + num_possible_cpus());
+	if (!handle->table)
+		goto error_table_alloc;
 
-	chan = zalloc_shm(shm_header, sizeof(struct channel));
+	/* Calculate the shm allocation layout */
+	shmsize = sizeof(struct channel);
+	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
+		shmsize += sizeof(struct lttng_ust_lib_ring_buffer_shmp) * num_possible_cpus();
+	else
+		shmsize += sizeof(struct lttng_ust_lib_ring_buffer_shmp);
+
+	shmobj = shm_object_table_append(handle->table, shmsize);
+	if (!shmobj)
+		goto error_append;
+	/* struct channel is at object 0, offset 0 (hardcoded) */
+	set_shmp(handle->chan, zalloc_shm(shmobj, sizeof(struct channel)));
+	assert(handle->chan._ref.index == 0);
+	assert(handle->chan._ref.offset == 0);
+	chan = shmp(handle, handle->chan);
 	if (!chan)
-		goto destroy_shmem;
-	set_shmp(shm_header->chan, chan);
+		goto error_append;
 
 	ret = channel_backend_init(&chan->backend, name, config, priv,
-				   subbuf_size, num_subbuf, shm_header);
+				   subbuf_size, num_subbuf, handle);
 	if (ret)
-		goto destroy_shmem;
+		goto error_backend_init;
 
 	chan->commit_count_mask = (~0UL >> chan->backend.num_subbuf_order);
 	//TODO
 	//chan->switch_timer_interval = usecs_to_jiffies(switch_timer_interval);
 	//chan->read_timer_interval = usecs_to_jiffies(read_timer_interval);
-	urcu_ref_init(&chan->ref);
 	//TODO
 	//init_waitqueue_head(&chan->read_wait);
 	//init_waitqueue_head(&chan->hp_wait);
@@ -479,32 +488,77 @@ struct channel *channel_create(const struct lib_ring_buffer_config *config,
 		 * In that off case, we need to allocate for all possible cpus.
 		 */
 		for_each_possible_cpu(cpu) {
-			struct lib_ring_buffer *buf = &shmp(chan->backend.buf)[cpu];
-			lib_ring_buffer_start_switch_timer(buf);
-			lib_ring_buffer_start_read_timer(buf);
+			struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[cpu].shmp);
+			lib_ring_buffer_start_switch_timer(buf, handle);
+			lib_ring_buffer_start_read_timer(buf, handle);
 		}
 	} else {
-		struct lib_ring_buffer *buf = shmp(chan->backend.buf);
+		struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[0].shmp);
 
-		lib_ring_buffer_start_switch_timer(buf);
-		lib_ring_buffer_start_read_timer(buf);
+		lib_ring_buffer_start_switch_timer(buf, handle);
+		lib_ring_buffer_start_read_timer(buf, handle);
 	}
+	ref = &handle->chan._ref;
+	shm_get_object_data(handle, ref, shm_fd, wait_fd, memory_map_size);
+	return handle;
+
+error_backend_init:
+error_append:
+	shm_object_table_destroy(handle->table);
+error_table_alloc:
+	free(handle);
+	return NULL;
+}
+
+struct lttng_ust_shm_handle *channel_handle_create(int shm_fd, int wait_fd,
+					uint64_t memory_map_size)
+{
+	struct lttng_ust_shm_handle *handle;
+	struct shm_object *object;
 
-	return chan;
+	handle = zmalloc(sizeof(struct lttng_ust_shm_handle));
+	if (!handle)
+		return NULL;
 
-destroy_shmem:
-	ret = shmctl(*shmid, IPC_RMID, NULL);
-	if (ret == -1) {
-		perror("shmctl");
-	}
+	/* Allocate table for channel + per-cpu buffers */
+	handle->table = shm_object_table_create(1 + num_possible_cpus());
+	if (!handle->table)
+		goto error_table_alloc;
+	/* Add channel object */
+	object = shm_object_table_append_shadow(handle->table,
+			shm_fd, wait_fd, memory_map_size);
+	if (!object)
+		goto error_table_object;
+	/* struct channel is at object 0, offset 0 (hardcoded) */
+	handle->chan._ref.index = 0;
+	handle->chan._ref.offset = 0;
+	return handle;
+
+error_table_object:
+	shm_object_table_destroy(handle->table);
+error_table_alloc:
+	free(handle);
 	return NULL;
 }
 
+int channel_handle_add_stream(struct lttng_ust_shm_handle *handle,
+		int shm_fd, int wait_fd, uint64_t memory_map_size)
+{
+	struct shm_object *object;
+
+	/* Add stream object */
+	object = shm_object_table_append_shadow(handle->table,
+			shm_fd, wait_fd, memory_map_size);
+	if (!object)
+		return -1;
+	return 0;
+}
+
 static
-void channel_release(struct urcu_ref *ref)
+void channel_release(struct channel *chan, struct lttng_ust_shm_handle *handle,
+		int shadow)
 {
-	struct channel *chan = caa_container_of(ref, struct channel, ref);
-	channel_free(chan);
+	channel_free(chan, handle, shadow);
 }
 
 /**
@@ -512,30 +566,37 @@ void channel_release(struct urcu_ref *ref)
  * @chan: channel to destroy
  *
  * Holds cpu hotplug.
- * Call "destroy" callback, finalize channels, wait for readers to release their
- * reference, then destroy ring buffer data. Note that when readers have
- * completed data consumption of finalized channels, get_subbuf() will return
- * -ENODATA. They should release their handle at that point.
- * Returns the private data pointer.
+ * Call "destroy" callback, finalize channels, decrement the channel
+ * reference count. Note that when readers have completed data
+ * consumption of finalized channels, get_subbuf() will return -ENODATA.
+ * They should release their handle at that point.  Returns the private
+ * data pointer.
  */
-void *channel_destroy(struct channel *chan)
+void *channel_destroy(struct channel *chan, struct lttng_ust_shm_handle *handle,
+		int shadow)
 {
-	int cpu;
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	void *priv;
+	int cpu;
+
+	if (shadow) {
+		channel_release(chan, handle, shadow);
+		return NULL;
+	}
 
-	channel_unregister_notifiers(chan);
+	channel_unregister_notifiers(chan, handle);
 
 	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
 		for_each_channel_cpu(cpu, chan) {
-			struct lib_ring_buffer *buf = &shmp(chan->backend.buf)[cpu];
+			struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[cpu].shmp);
 
 			if (config->cb.buffer_finalize)
 				config->cb.buffer_finalize(buf,
 							   chan->backend.priv,
-							   cpu);
+							   cpu, handle);
 			if (buf->backend.allocated)
-				lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH);
+				lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH,
+						handle);
 			/*
 			 * Perform flush before writing to finalized.
 			 */
@@ -544,12 +605,13 @@ void *channel_destroy(struct channel *chan)
 			//wake_up_interruptible(&buf->read_wait);
 		}
 	} else {
-		struct lib_ring_buffer *buf = shmp(chan->backend.buf);
+		struct lttng_ust_lib_ring_buffer *buf = shmp(handle, chan->backend.buf[0].shmp);
 
 		if (config->cb.buffer_finalize)
-			config->cb.buffer_finalize(buf, chan->backend.priv, -1);
+			config->cb.buffer_finalize(buf, chan->backend.priv, -1, handle);
 		if (buf->backend.allocated)
-			lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH);
+			lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH,
+						handle);
 		/*
 		 * Perform flush before writing to finalized.
 		 */
@@ -560,40 +622,70 @@ void *channel_destroy(struct channel *chan)
 	CMM_ACCESS_ONCE(chan->finalized) = 1;
 	//wake_up_interruptible(&chan->hp_wait);
 	//wake_up_interruptible(&chan->read_wait);
-	urcu_ref_put(&chan->ref, channel_release);
+	/*
+	 * sessiond/consumer are keeping a reference on the shm file
+	 * descriptor directly. No need to refcount.
+	 */
 	priv = chan->backend.priv;
+	channel_release(chan, handle, shadow);
 	return priv;
 }
 
-struct lib_ring_buffer *channel_get_ring_buffer(
-					const struct lib_ring_buffer_config *config,
-					struct channel *chan, int cpu)
+struct lttng_ust_lib_ring_buffer *channel_get_ring_buffer(
+					const struct lttng_ust_lib_ring_buffer_config *config,
+					struct channel *chan, int cpu,
+					struct lttng_ust_shm_handle *handle,
+					int *shm_fd, int *wait_fd,
+					uint64_t *memory_map_size)
 {
-	if (config->alloc == RING_BUFFER_ALLOC_GLOBAL)
-		return shmp(chan->backend.buf);
-	else
-		return &shmp(chan->backend.buf)[cpu];
+	struct shm_ref *ref;
+
+	if (config->alloc == RING_BUFFER_ALLOC_GLOBAL) {
+		ref = &chan->backend.buf[0].shmp._ref;
+		shm_get_object_data(handle, ref, shm_fd, wait_fd,
+			memory_map_size);
+		return shmp(handle, chan->backend.buf[0].shmp);
+	} else {
+		if (cpu >= num_possible_cpus())
+			return NULL;
+		ref = &chan->backend.buf[cpu].shmp._ref;
+		shm_get_object_data(handle, ref, shm_fd, wait_fd,
+			memory_map_size);
+		return shmp(handle, chan->backend.buf[cpu].shmp);
+	}
 }
 
-int lib_ring_buffer_open_read(struct lib_ring_buffer *buf)
+int lib_ring_buffer_open_read(struct lttng_ust_lib_ring_buffer *buf,
+			      struct lttng_ust_shm_handle *handle,
+			      int shadow)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-
+	if (shadow) {
+		if (uatomic_cmpxchg(&buf->active_shadow_readers, 0, 1) != 0)
+			return -EBUSY;
+		cmm_smp_mb();
+		return 0;
+	}
 	if (uatomic_cmpxchg(&buf->active_readers, 0, 1) != 0)
 		return -EBUSY;
-	urcu_ref_get(&chan->ref);
 	cmm_smp_mb();
 	return 0;
 }
 
-void lib_ring_buffer_release_read(struct lib_ring_buffer *buf)
+void lib_ring_buffer_release_read(struct lttng_ust_lib_ring_buffer *buf,
+				  struct lttng_ust_shm_handle *handle,
+				  int shadow)
 {
-	struct channel *chan = shmp(buf->backend.chan);
+	struct channel *chan = shmp(handle, buf->backend.chan);
 
+	if (shadow) {
+		CHAN_WARN_ON(chan, uatomic_read(&buf->active_shadow_readers) != 1);
+		cmm_smp_mb();
+		uatomic_dec(&buf->active_shadow_readers);
+		return;
+	}
 	CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1);
 	cmm_smp_mb();
 	uatomic_dec(&buf->active_readers);
-	urcu_ref_put(&chan->ref, channel_release);
 }
 
 /**
@@ -606,11 +698,12 @@ void lib_ring_buffer_release_read(struct lib_ring_buffer *buf)
  * data to read at consumed position, or 0 if the get operation succeeds.
  */
 
-int lib_ring_buffer_snapshot(struct lib_ring_buffer *buf,
-			     unsigned long *consumed, unsigned long *produced)
+int lib_ring_buffer_snapshot(struct lttng_ust_lib_ring_buffer *buf,
+			     unsigned long *consumed, unsigned long *produced,
+			     struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long consumed_cur, write_offset;
 	int finalized;
 
@@ -659,14 +752,16 @@ nodata:
  * @buf: ring buffer
  * @consumed_new: new consumed count value
  */
-void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
-				   unsigned long consumed_new)
+void lib_ring_buffer_move_consumer(struct lttng_ust_lib_ring_buffer *buf,
+				   unsigned long consumed_new,
+				   struct lttng_ust_shm_handle *handle)
 {
-	struct lib_ring_buffer_backend *bufb = &buf->backend;
-	struct channel *chan = shmp(bufb->chan);
+	struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend;
+	struct channel *chan = shmp(handle, bufb->chan);
 	unsigned long consumed;
 
-	CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1);
+	CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1
+			&& uatomic_read(&buf->active_shadow_readers) != 1);
 
 	/*
 	 * Only push the consumed value forward.
@@ -687,11 +782,12 @@ void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
  * Returns -ENODATA if buffer is finalized, -EAGAIN if there is currently no
  * data to read at consumed position, or 0 if the get operation succeeds.
  */
-int lib_ring_buffer_get_subbuf(struct lib_ring_buffer *buf,
-			       unsigned long consumed)
+int lib_ring_buffer_get_subbuf(struct lttng_ust_lib_ring_buffer *buf,
+			       unsigned long consumed,
+			       struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long consumed_cur, consumed_idx, commit_count, write_offset;
 	int ret;
 	int finalized;
@@ -704,7 +800,7 @@ retry:
 	cmm_smp_rmb();
 	consumed_cur = uatomic_read(&buf->consumed);
 	consumed_idx = subbuf_index(consumed, chan);
-	commit_count = v_read(config, &shmp(buf->commit_cold)[consumed_idx].cc_sb);
+	commit_count = v_read(config, &shmp_index(handle, buf->commit_cold, consumed_idx)->cc_sb);
 	/*
 	 * Make sure we read the commit count before reading the buffer
 	 * data and the write offset. Correct consumed offset ordering
@@ -754,7 +850,8 @@ retry:
 	 * looking for matches the one contained in the subbuffer id.
 	 */
 	ret = update_read_sb_index(config, &buf->backend, &chan->backend,
-				   consumed_idx, buf_trunc_val(consumed, chan));
+				   consumed_idx, buf_trunc_val(consumed, chan),
+				   handle);
 	if (ret)
 		goto retry;
 	subbuffer_id_clear_noref(config, &buf->backend.buf_rsb.id);
@@ -779,14 +876,16 @@ nodata:
  * lib_ring_buffer_put_subbuf - release exclusive subbuffer access
  * @buf: ring buffer
  */
-void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf)
+void lib_ring_buffer_put_subbuf(struct lttng_ust_lib_ring_buffer *buf,
+				struct lttng_ust_shm_handle *handle)
 {
-	struct lib_ring_buffer_backend *bufb = &buf->backend;
-	struct channel *chan = shmp(bufb->chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct lttng_ust_lib_ring_buffer_backend *bufb = &buf->backend;
+	struct channel *chan = shmp(handle, bufb->chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long read_sb_bindex, consumed_idx, consumed;
 
-	CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1);
+	CHAN_WARN_ON(chan, uatomic_read(&buf->active_readers) != 1
+			&& uatomic_read(&buf->active_shadow_readers) != 1);
 
 	if (!buf->get_subbuf) {
 		/*
@@ -807,9 +906,9 @@ void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf)
 	 */
 	read_sb_bindex = subbuffer_id_get_index(config, bufb->buf_rsb.id);
 	v_add(config, v_read(config,
-			     &shmp(bufb->array)[read_sb_bindex]->records_unread),
+			     &shmp(handle, shmp_index(handle, bufb->array, read_sb_bindex)->shmp)->records_unread),
 	      &bufb->records_read);
-	v_set(config, &shmp(bufb->array)[read_sb_bindex]->records_unread, 0);
+	v_set(config, &shmp(handle, shmp_index(handle, bufb->array, read_sb_bindex)->shmp)->records_unread, 0);
 	CHAN_WARN_ON(chan, config->mode == RING_BUFFER_OVERWRITE
 		     && subbuffer_id_is_noref(config, bufb->buf_rsb.id));
 	subbuffer_id_set_noref(config, &bufb->buf_rsb.id);
@@ -824,7 +923,8 @@ void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf)
 	 */
 	consumed_idx = subbuf_index(consumed, chan);
 	update_read_sb_index(config, &buf->backend, &chan->backend,
-			     consumed_idx, buf_trunc_val(consumed, chan));
+			     consumed_idx, buf_trunc_val(consumed, chan),
+			     handle);
 	/*
 	 * update_read_sb_index return value ignored. Don't exchange sub-buffer
 	 * if the writer concurrently updated it.
@@ -836,17 +936,18 @@ void lib_ring_buffer_put_subbuf(struct lib_ring_buffer *buf)
  * position and the writer position. (inclusive)
  */
 static
-void lib_ring_buffer_print_subbuffer_errors(struct lib_ring_buffer *buf,
+void lib_ring_buffer_print_subbuffer_errors(struct lttng_ust_lib_ring_buffer *buf,
 					    struct channel *chan,
 					    unsigned long cons_offset,
-					    int cpu)
+					    int cpu,
+					    struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long cons_idx, commit_count, commit_count_sb;
 
 	cons_idx = subbuf_index(cons_offset, chan);
-	commit_count = v_read(config, &shmp(buf->commit_hot)[cons_idx].cc);
-	commit_count_sb = v_read(config, &shmp(buf->commit_cold)[cons_idx].cc_sb);
+	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, cons_idx)->cc);
+	commit_count_sb = v_read(config, &shmp_index(handle, buf->commit_cold, cons_idx)->cc_sb);
 
 	if (subbuf_offset(commit_count, chan) != 0)
 		ERRMSG("ring buffer %s, cpu %d: "
@@ -862,11 +963,12 @@ void lib_ring_buffer_print_subbuffer_errors(struct lib_ring_buffer *buf,
 }
 
 static
-void lib_ring_buffer_print_buffer_errors(struct lib_ring_buffer *buf,
+void lib_ring_buffer_print_buffer_errors(struct lttng_ust_lib_ring_buffer *buf,
 					 struct channel *chan,
-					 void *priv, int cpu)
+					 void *priv, int cpu,
+					 struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long write_offset, cons_offset;
 
 	/*
@@ -894,14 +996,15 @@ void lib_ring_buffer_print_buffer_errors(struct lib_ring_buffer *buf,
 		     - cons_offset) > 0;
 	     cons_offset = subbuf_align(cons_offset, chan))
 		lib_ring_buffer_print_subbuffer_errors(buf, chan, cons_offset,
-						       cpu);
+						       cpu, handle);
 }
 
 static
 void lib_ring_buffer_print_errors(struct channel *chan,
-				  struct lib_ring_buffer *buf, int cpu)
+				  struct lttng_ust_lib_ring_buffer *buf, int cpu,
+				  struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	void *priv = chan->backend.priv;
 
 	ERRMSG("ring buffer %s, cpu %d: %lu records written, "
@@ -921,7 +1024,7 @@ void lib_ring_buffer_print_errors(struct channel *chan,
 		       v_read(config, &buf->records_lost_wrap),
 		       v_read(config, &buf->records_lost_big));
 
-	lib_ring_buffer_print_buffer_errors(buf, chan, priv, cpu);
+	lib_ring_buffer_print_buffer_errors(buf, chan, priv, cpu, handle);
 }
 
 /*
@@ -930,16 +1033,17 @@ void lib_ring_buffer_print_errors(struct channel *chan,
  * Only executed when the buffer is finalized, in SWITCH_FLUSH.
  */
 static
-void lib_ring_buffer_switch_old_start(struct lib_ring_buffer *buf,
+void lib_ring_buffer_switch_old_start(struct lttng_ust_lib_ring_buffer *buf,
 				      struct channel *chan,
 				      struct switch_offsets *offsets,
-				      u64 tsc)
+				      u64 tsc,
+				      struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long oldidx = subbuf_index(offsets->old, chan);
 	unsigned long commit_count;
 
-	config->cb.buffer_begin(buf, tsc, oldidx);
+	config->cb.buffer_begin(buf, tsc, oldidx, handle);
 
 	/*
 	 * Order all writes to buffer before the commit count update that will
@@ -947,14 +1051,15 @@ void lib_ring_buffer_switch_old_start(struct lib_ring_buffer *buf,
 	 */
 	cmm_smp_wmb();
 	v_add(config, config->cb.subbuffer_header_size(),
-	      &shmp(buf->commit_hot)[oldidx].cc);
-	commit_count = v_read(config, &shmp(buf->commit_hot)[oldidx].cc);
+	      &shmp_index(handle, buf->commit_hot, oldidx)->cc);
+	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc);
 	/* Check if the written buffer has to be delivered */
 	lib_ring_buffer_check_deliver(config, buf, chan, offsets->old,
-				      commit_count, oldidx);
+				      commit_count, oldidx, handle);
 	lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx,
 					     offsets->old, commit_count,
-					     config->cb.subbuffer_header_size());
+					     config->cb.subbuffer_header_size(),
+					     handle);
 }
 
 /*
@@ -966,31 +1071,33 @@ void lib_ring_buffer_switch_old_start(struct lib_ring_buffer *buf,
  * subbuffer.
  */
 static
-void lib_ring_buffer_switch_old_end(struct lib_ring_buffer *buf,
+void lib_ring_buffer_switch_old_end(struct lttng_ust_lib_ring_buffer *buf,
 				    struct channel *chan,
 				    struct switch_offsets *offsets,
-				    u64 tsc)
+				    u64 tsc,
+				    struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long oldidx = subbuf_index(offsets->old - 1, chan);
 	unsigned long commit_count, padding_size, data_size;
 
 	data_size = subbuf_offset(offsets->old - 1, chan) + 1;
 	padding_size = chan->backend.subbuf_size - data_size;
-	subbuffer_set_data_size(config, &buf->backend, oldidx, data_size);
+	subbuffer_set_data_size(config, &buf->backend, oldidx, data_size,
+				handle);
 
 	/*
 	 * Order all writes to buffer before the commit count update that will
 	 * determine that the subbuffer is full.
 	 */
 	cmm_smp_wmb();
-	v_add(config, padding_size, &shmp(buf->commit_hot)[oldidx].cc);
-	commit_count = v_read(config, &shmp(buf->commit_hot)[oldidx].cc);
+	v_add(config, padding_size, &shmp_index(handle, buf->commit_hot, oldidx)->cc);
+	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, oldidx)->cc);
 	lib_ring_buffer_check_deliver(config, buf, chan, offsets->old - 1,
-				      commit_count, oldidx);
+				      commit_count, oldidx, handle);
 	lib_ring_buffer_write_commit_counter(config, buf, chan, oldidx,
 					     offsets->old, commit_count,
-					     padding_size);
+					     padding_size, handle);
 }
 
 /*
@@ -1001,16 +1108,17 @@ void lib_ring_buffer_switch_old_end(struct lib_ring_buffer *buf,
  * that this code is executed before the deliver of this sub-buffer.
  */
 static
-void lib_ring_buffer_switch_new_start(struct lib_ring_buffer *buf,
+void lib_ring_buffer_switch_new_start(struct lttng_ust_lib_ring_buffer *buf,
 				      struct channel *chan,
 				      struct switch_offsets *offsets,
-				      u64 tsc)
+				      u64 tsc,
+				      struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long beginidx = subbuf_index(offsets->begin, chan);
 	unsigned long commit_count;
 
-	config->cb.buffer_begin(buf, tsc, beginidx);
+	config->cb.buffer_begin(buf, tsc, beginidx, handle);
 
 	/*
 	 * Order all writes to buffer before the commit count update that will
@@ -1018,14 +1126,15 @@ void lib_ring_buffer_switch_new_start(struct lib_ring_buffer *buf,
 	 */
 	cmm_smp_wmb();
 	v_add(config, config->cb.subbuffer_header_size(),
-	      &shmp(buf->commit_hot)[beginidx].cc);
-	commit_count = v_read(config, &shmp(buf->commit_hot)[beginidx].cc);
+	      &shmp_index(handle, buf->commit_hot, beginidx)->cc);
+	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, beginidx)->cc);
 	/* Check if the written buffer has to be delivered */
 	lib_ring_buffer_check_deliver(config, buf, chan, offsets->begin,
-				      commit_count, beginidx);
+				      commit_count, beginidx, handle);
 	lib_ring_buffer_write_commit_counter(config, buf, chan, beginidx,
 					     offsets->begin, commit_count,
-					     config->cb.subbuffer_header_size());
+					     config->cb.subbuffer_header_size(),
+					     handle);
 }
 
 /*
@@ -1035,31 +1144,33 @@ void lib_ring_buffer_switch_new_start(struct lib_ring_buffer *buf,
  * have to do the deliver themselves.
  */
 static
-void lib_ring_buffer_switch_new_end(struct lib_ring_buffer *buf,
-					    struct channel *chan,
-					    struct switch_offsets *offsets,
-					    u64 tsc)
+void lib_ring_buffer_switch_new_end(struct lttng_ust_lib_ring_buffer *buf,
+				    struct channel *chan,
+				    struct switch_offsets *offsets,
+				    u64 tsc,
+				    struct lttng_ust_shm_handle *handle)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long endidx = subbuf_index(offsets->end - 1, chan);
 	unsigned long commit_count, padding_size, data_size;
 
 	data_size = subbuf_offset(offsets->end - 1, chan) + 1;
 	padding_size = chan->backend.subbuf_size - data_size;
-	subbuffer_set_data_size(config, &buf->backend, endidx, data_size);
+	subbuffer_set_data_size(config, &buf->backend, endidx, data_size,
+				handle);
 
 	/*
 	 * Order all writes to buffer before the commit count update that will
 	 * determine that the subbuffer is full.
 	 */
 	cmm_smp_wmb();
-	v_add(config, padding_size, &shmp(buf->commit_hot)[endidx].cc);
-	commit_count = v_read(config, &shmp(buf->commit_hot)[endidx].cc);
+	v_add(config, padding_size, &shmp_index(handle, buf->commit_hot, endidx)->cc);
+	commit_count = v_read(config, &shmp_index(handle, buf->commit_hot, endidx)->cc);
 	lib_ring_buffer_check_deliver(config, buf, chan, offsets->end - 1,
-				  commit_count, endidx);
+				  commit_count, endidx, handle);
 	lib_ring_buffer_write_commit_counter(config, buf, chan, endidx,
 					     offsets->end, commit_count,
-					     padding_size);
+					     padding_size, handle);
 }
 
 /*
@@ -1069,12 +1180,12 @@ void lib_ring_buffer_switch_new_end(struct lib_ring_buffer *buf,
  */
 static
 int lib_ring_buffer_try_switch_slow(enum switch_mode mode,
-				    struct lib_ring_buffer *buf,
+				    struct lttng_ust_lib_ring_buffer *buf,
 				    struct channel *chan,
 				    struct switch_offsets *offsets,
 				    u64 *tsc)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	unsigned long off;
 
 	offsets->begin = v_read(config, &buf->offset);
@@ -1101,7 +1212,7 @@ int lib_ring_buffer_try_switch_slow(enum switch_mode mode,
 	 * quiescence guarantees for the fusion merge.
 	 */
 	if (mode == SWITCH_FLUSH || off > 0) {
-		if (unlikely(off == 0)) {
+		if (caa_unlikely(off == 0)) {
 			/*
 			 * The client does not save any header information.
 			 * Don't switch empty subbuffer on finalize, because it
@@ -1130,10 +1241,11 @@ int lib_ring_buffer_try_switch_slow(enum switch_mode mode,
  * operations, this function must be called from the CPU which owns the buffer
  * for a ACTIVE flush.
  */
-void lib_ring_buffer_switch_slow(struct lib_ring_buffer *buf, enum switch_mode mode)
+void lib_ring_buffer_switch_slow(struct lttng_ust_lib_ring_buffer *buf, enum switch_mode mode,
+				 struct lttng_ust_shm_handle *handle)
 {
-	struct channel *chan = shmp(buf->backend.chan);
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	struct channel *chan = shmp(handle, buf->backend.chan);
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
 	struct switch_offsets offsets;
 	unsigned long oldidx;
 	u64 tsc;
@@ -1164,20 +1276,20 @@ void lib_ring_buffer_switch_slow(struct lib_ring_buffer *buf, enum switch_mode m
 	lib_ring_buffer_reserve_push_reader(buf, chan, offsets.old);
 
 	oldidx = subbuf_index(offsets.old, chan);
-	lib_ring_buffer_clear_noref(config, &buf->backend, oldidx);
+	lib_ring_buffer_clear_noref(config, &buf->backend, oldidx, handle);
 
 	/*
 	 * May need to populate header start on SWITCH_FLUSH.
 	 */
 	if (offsets.switch_old_start) {
-		lib_ring_buffer_switch_old_start(buf, chan, &offsets, tsc);
+		lib_ring_buffer_switch_old_start(buf, chan, &offsets, tsc, handle);
 		offsets.old += config->cb.subbuffer_header_size();
 	}
 
 	/*
 	 * Switch old subbuffer.
 	 */
-	lib_ring_buffer_switch_old_end(buf, chan, &offsets, tsc);
+	lib_ring_buffer_switch_old_end(buf, chan, &offsets, tsc, handle);
 }
 
 /*
@@ -1188,12 +1300,13 @@ void lib_ring_buffer_switch_slow(struct lib_ring_buffer *buf, enum switch_mode m
  * -EIO if data cannot be written into the buffer for any other reason.
  */
 static
-int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf,
+int lib_ring_buffer_try_reserve_slow(struct lttng_ust_lib_ring_buffer *buf,
 				     struct channel *chan,
 				     struct switch_offsets *offsets,
-				     struct lib_ring_buffer_ctx *ctx)
+				     struct lttng_ust_lib_ring_buffer_ctx *ctx)
 {
-	const struct lib_ring_buffer_config *config = chan->backend.config;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
+	struct lttng_ust_shm_handle *handle = ctx->handle;
 	unsigned long reserve_commit_diff;
 
 	offsets->begin = v_read(config, &buf->offset);
@@ -1210,7 +1323,7 @@ int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf,
 	if (last_tsc_overflow(config, buf, ctx->tsc))
 		ctx->rflags |= RING_BUFFER_RFLAG_FULL_TSC;
 
-	if (unlikely(subbuf_offset(offsets->begin, ctx->chan) == 0)) {
+	if (caa_unlikely(subbuf_offset(offsets->begin, ctx->chan) == 0)) {
 		offsets->switch_new_start = 1;		/* For offsets->begin */
 	} else {
 		offsets->size = config->cb.record_header_size(config, chan,
@@ -1221,19 +1334,19 @@ int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf,
 			lib_ring_buffer_align(offsets->begin + offsets->size,
 					      ctx->largest_align)
 			+ ctx->data_size;
-		if (unlikely(subbuf_offset(offsets->begin, chan) +
+		if (caa_unlikely(subbuf_offset(offsets->begin, chan) +
 			     offsets->size > chan->backend.subbuf_size)) {
 			offsets->switch_old_end = 1;	/* For offsets->old */
 			offsets->switch_new_start = 1;	/* For offsets->begin */
 		}
 	}
-	if (unlikely(offsets->switch_new_start)) {
+	if (caa_unlikely(offsets->switch_new_start)) {
 		unsigned long sb_index;
 
 		/*
 		 * We are typically not filling the previous buffer completely.
 		 */
-		if (likely(offsets->switch_old_end))
+		if (caa_likely(offsets->switch_old_end))
 			offsets->begin = subbuf_align(offsets->begin, chan);
 		offsets->begin = offsets->begin
 				 + config->cb.subbuffer_header_size();
@@ -1243,11 +1356,11 @@ int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf,
 		  (buf_trunc(offsets->begin, chan)
 		   >> chan->backend.num_subbuf_order)
 		  - ((unsigned long) v_read(config,
-					    &shmp(buf->commit_cold)[sb_index].cc_sb)
+					    &shmp_index(handle, buf->commit_cold, sb_index)->cc_sb)
 		     & chan->commit_count_mask);
-		if (likely(reserve_commit_diff == 0)) {
+		if (caa_likely(reserve_commit_diff == 0)) {
 			/* Next subbuffer not being written to. */
-			if (unlikely(config->mode != RING_BUFFER_OVERWRITE &&
+			if (caa_unlikely(config->mode != RING_BUFFER_OVERWRITE &&
 				subbuf_trunc(offsets->begin, chan)
 				 - subbuf_trunc((unsigned long)
 				     uatomic_read(&buf->consumed), chan)
@@ -1285,7 +1398,7 @@ int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf,
 			lib_ring_buffer_align(offsets->begin + offsets->size,
 					      ctx->largest_align)
 			+ ctx->data_size;
-		if (unlikely(subbuf_offset(offsets->begin, chan)
+		if (caa_unlikely(subbuf_offset(offsets->begin, chan)
 			     + offsets->size > chan->backend.subbuf_size)) {
 			/*
 			 * Record too big for subbuffers, report error, don't
@@ -1307,7 +1420,7 @@ int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf,
 	}
 	offsets->end = offsets->begin + offsets->size;
 
-	if (unlikely(subbuf_offset(offsets->end, chan) == 0)) {
+	if (caa_unlikely(subbuf_offset(offsets->end, chan) == 0)) {
 		/*
 		 * The offset_end will fall at the very beginning of the next
 		 * subbuffer.
@@ -1325,18 +1438,19 @@ int lib_ring_buffer_try_reserve_slow(struct lib_ring_buffer *buf,
  * -EIO for other errors, else returns 0.
  * It will take care of sub-buffer switching.
  */
-int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx)
+int lib_ring_buffer_reserve_slow(struct lttng_ust_lib_ring_buffer_ctx *ctx)
 {
 	struct channel *chan = ctx->chan;
-	const struct lib_ring_buffer_config *config = chan->backend.config;
-	struct lib_ring_buffer *buf;
+	struct lttng_ust_shm_handle *handle = ctx->handle;
+	const struct lttng_ust_lib_ring_buffer_config *config = &chan->backend.config;
+	struct lttng_ust_lib_ring_buffer *buf;
 	struct switch_offsets offsets;
 	int ret;
 
 	if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
-		buf = &shmp(chan->backend.buf)[ctx->cpu];
+		buf = shmp(handle, chan->backend.buf[ctx->cpu].shmp);
 	else
-		buf = shmp(chan->backend.buf);
+		buf = shmp(handle, chan->backend.buf[0].shmp);
 	ctx->buf = buf;
 
 	offsets.size = 0;
@@ -1344,9 +1458,9 @@ int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx)
 	do {
 		ret = lib_ring_buffer_try_reserve_slow(buf, chan, &offsets,
 						       ctx);
-		if (unlikely(ret))
+		if (caa_unlikely(ret))
 			return ret;
-	} while (unlikely(v_cmpxchg(config, &buf->offset, offsets.old,
+	} while (caa_unlikely(v_cmpxchg(config, &buf->offset, offsets.old,
 				    offsets.end)
 			  != offsets.old));
 
@@ -1367,25 +1481,27 @@ int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx)
 	 * Clear noref flag for this subbuffer.
 	 */
 	lib_ring_buffer_clear_noref(config, &buf->backend,
-				    subbuf_index(offsets.end - 1, chan));
+				    subbuf_index(offsets.end - 1, chan),
+				    handle);
 
 	/*
 	 * Switch old subbuffer if needed.
 	 */
-	if (unlikely(offsets.switch_old_end)) {
+	if (caa_unlikely(offsets.switch_old_end)) {
 		lib_ring_buffer_clear_noref(config, &buf->backend,
-					    subbuf_index(offsets.old - 1, chan));
-		lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx->tsc);
+					    subbuf_index(offsets.old - 1, chan),
+					    handle);
+		lib_ring_buffer_switch_old_end(buf, chan, &offsets, ctx->tsc, handle);
 	}
 
 	/*
 	 * Populate new subbuffer.
 	 */
-	if (unlikely(offsets.switch_new_start))
-		lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc);
+	if (caa_unlikely(offsets.switch_new_start))
+		lib_ring_buffer_switch_new_start(buf, chan, &offsets, ctx->tsc, handle);
 
-	if (unlikely(offsets.switch_new_end))
-		lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc);
+	if (caa_unlikely(offsets.switch_new_end))
+		lib_ring_buffer_switch_new_end(buf, chan, &offsets, ctx->tsc, handle);
 
 	ctx->slot_size = offsets.size;
 	ctx->pre_offset = offsets.begin;