Fix: do not generate packet at destroy after stop

[lttng-modules.git] / lib / ringbuffer / ring_buffer_frontend.c

diff --git a/lib/ringbuffer/ring_buffer_frontend.c b/lib/ringbuffer/ring_buffer_frontend.c
index ae0b9e3986267a8b79e8395d13cd23d55cc357c7..c48ac620668f97f3ea7f3ff1222c16f62a40add9 100644 (file)
--- a/lib/ringbuffer/ring_buffer_frontend.c
+++ b/lib/ringbuffer/ring_buffer_frontend.c
@@ -55,12 +55,14 @@
 #include <linux/module.h>
 #include <linux/percpu.h>
 
-#include "../../wrapper/ringbuffer/config.h"
-#include "../../wrapper/ringbuffer/backend.h"
-#include "../../wrapper/ringbuffer/frontend.h"
-#include "../../wrapper/ringbuffer/iterator.h"
-#include "../../wrapper/ringbuffer/nohz.h"
-#include "../../wrapper/atomic.h"
+#include <wrapper/ringbuffer/config.h>
+#include <wrapper/ringbuffer/backend.h>
+#include <wrapper/ringbuffer/frontend.h>
+#include <wrapper/ringbuffer/iterator.h>
+#include <wrapper/ringbuffer/nohz.h>
+#include <wrapper/atomic.h>
+#include <wrapper/kref.h>
+#include <wrapper/percpu-defs.h>
 
 /*
  * Internal structure representing offsets to use at a sub-buffer switch.
@@ -90,6 +92,9 @@ EXPORT_PER_CPU_SYMBOL(lib_ring_buffer_nesting);
 static
 void lib_ring_buffer_print_errors(struct channel *chan,
                                  struct lib_ring_buffer *buf, int cpu);
+static
+void _lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf,
+               enum switch_mode mode);
 
 /*
  * Must be called under cpu hotplug protection.
@@ -498,16 +503,16 @@ static int notrace ring_buffer_tick_nohz_callback(struct notifier_block *nb,
                raw_spin_unlock(&buf->raw_tick_nohz_spinlock);
                break;
        case TICK_NOHZ_STOP:
-               spin_lock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_lock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                lib_ring_buffer_stop_switch_timer(buf);
                lib_ring_buffer_stop_read_timer(buf);
-               spin_unlock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_unlock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                break;
        case TICK_NOHZ_RESTART:
-               spin_lock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_lock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                lib_ring_buffer_start_read_timer(buf);
                lib_ring_buffer_start_switch_timer(buf);
-               spin_unlock(&__get_cpu_var(ring_buffer_nohz_lock));
+               spin_unlock(lttng_this_cpu_ptr(&ring_buffer_nohz_lock));
                break;
        }
 
@@ -584,6 +589,63 @@ static void channel_unregister_notifiers(struct channel *chan)
        channel_backend_unregister_notifiers(&chan->backend);
 }
 
+static void lib_ring_buffer_set_quiescent(struct lib_ring_buffer *buf)
+{
+       if (!buf->quiescent) {
+               buf->quiescent = true;
+               _lib_ring_buffer_switch_remote(buf, SWITCH_FLUSH);
+       }
+}
+
+static void lib_ring_buffer_clear_quiescent(struct lib_ring_buffer *buf)
+{
+       buf->quiescent = false;
+}
+
+void lib_ring_buffer_set_quiescent_channel(struct channel *chan)
+{
+       int cpu;
+       const struct lib_ring_buffer_config *config = &chan->backend.config;
+
+       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+               get_online_cpus();
+               for_each_channel_cpu(cpu, chan) {
+                       struct lib_ring_buffer *buf = per_cpu_ptr(chan->backend.buf,
+                                                             cpu);
+
+                       lib_ring_buffer_set_quiescent(buf);
+               }
+               put_online_cpus();
+       } else {
+               struct lib_ring_buffer *buf = chan->backend.buf;
+
+               lib_ring_buffer_set_quiescent(buf);
+       }
+}
+EXPORT_SYMBOL_GPL(lib_ring_buffer_set_quiescent_channel);
+
+void lib_ring_buffer_clear_quiescent_channel(struct channel *chan)
+{
+       int cpu;
+       const struct lib_ring_buffer_config *config = &chan->backend.config;
+
+       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
+               get_online_cpus();
+               for_each_channel_cpu(cpu, chan) {
+                       struct lib_ring_buffer *buf = per_cpu_ptr(chan->backend.buf,
+                                                             cpu);
+
+                       lib_ring_buffer_clear_quiescent(buf);
+               }
+               put_online_cpus();
+       } else {
+               struct lib_ring_buffer *buf = chan->backend.buf;
+
+               lib_ring_buffer_clear_quiescent(buf);
+       }
+}
+EXPORT_SYMBOL_GPL(lib_ring_buffer_clear_quiescent_channel);
+
 static void channel_free(struct channel *chan)
 {
        if (chan->backend.release_priv_ops) {
@@ -744,7 +806,7 @@ void *channel_destroy(struct channel *chan)
                                                           chan->backend.priv,
                                                           cpu);
                        if (buf->backend.allocated)
-                               lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH);
+                               lib_ring_buffer_set_quiescent(buf);
                        /*
                         * Perform flush before writing to finalized.
                         */
@@ -758,7 +820,7 @@ void *channel_destroy(struct channel *chan)
                if (config->cb.buffer_finalize)
                        config->cb.buffer_finalize(buf, chan->backend.priv, -1);
                if (buf->backend.allocated)
-                       lib_ring_buffer_switch_slow(buf, SWITCH_FLUSH);
+                       lib_ring_buffer_set_quiescent(buf);
                /*
                 * Perform flush before writing to finalized.
                 */
@@ -792,7 +854,10 @@ int lib_ring_buffer_open_read(struct lib_ring_buffer *buf)
 
        if (!atomic_long_add_unless(&buf->active_readers, 1, 1))
                return -EBUSY;
-       kref_get(&chan->ref);
+       if (!lttng_kref_get(&chan->ref)) {
+               atomic_long_dec(&buf->active_readers);
+               return -EOVERFLOW;
+       }
        lttng_smp_mb__after_atomic();
        return 0;
 }
@@ -1545,7 +1610,8 @@ static void remote_switch(void *info)
        lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
 }
 
-void lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf)
+static void _lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf,
+               enum switch_mode mode)
 {
        struct channel *chan = buf->backend.chan;
        const struct lib_ring_buffer_config *config = &chan->backend.config;
@@ -1555,7 +1621,7 @@ void lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf)
         * With global synchronization we don't need to use the IPI scheme.
         */
        if (config->sync == RING_BUFFER_SYNC_GLOBAL) {
-               lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
+               lib_ring_buffer_switch_slow(buf, mode);
                return;
        }
 
@@ -1574,10 +1640,15 @@ void lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf)
                                 remote_switch, buf, 1);
        if (ret) {
                /* Remote CPU is offline, do it ourself. */
-               lib_ring_buffer_switch_slow(buf, SWITCH_ACTIVE);
+               lib_ring_buffer_switch_slow(buf, mode);
        }
        put_online_cpus();
 }
+
+void lib_ring_buffer_switch_remote(struct lib_ring_buffer *buf)
+{
+       _lib_ring_buffer_switch_remote(buf, SWITCH_ACTIVE);
+}
 EXPORT_SYMBOL_GPL(lib_ring_buffer_switch_remote);
 
 /*
@@ -1738,6 +1809,25 @@ retry:
        return 0;
 }
 
+static struct lib_ring_buffer *get_current_buf(struct channel *chan, int cpu)
+{
+       const struct lib_ring_buffer_config *config = &chan->backend.config;
+
+       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
+               return per_cpu_ptr(chan->backend.buf, cpu);
+       else
+               return chan->backend.buf;
+}
+
+void lib_ring_buffer_lost_event_too_big(struct channel *chan)
+{
+       const struct lib_ring_buffer_config *config = &chan->backend.config;
+       struct lib_ring_buffer *buf = get_current_buf(chan, smp_processor_id());
+
+       v_inc(config, &buf->records_lost_big);
+}
+EXPORT_SYMBOL_GPL(lib_ring_buffer_lost_event_too_big);
+
 /**
  * lib_ring_buffer_reserve_slow - Atomic slot reservation in a buffer.
  * @ctx: ring buffer context.
@@ -1754,12 +1844,7 @@ int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx)
        struct switch_offsets offsets;
        int ret;
 
-       if (config->alloc == RING_BUFFER_ALLOC_PER_CPU)
-               buf = per_cpu_ptr(chan->backend.buf, ctx->cpu);
-       else
-               buf = chan->backend.buf;
-       ctx->buf = buf;
-
+       ctx->buf = buf = get_current_buf(chan, ctx->cpu);
        offsets.size = 0;
 
        do {