lttng-context-vtid.o lttng-context-ppid.o \
lttng-context-vppid.o lttng-calibrate.o \
lttng-context-hostname.o wrapper/random.o \
- probes/lttng.o wrapper/trace-clock.o
+ probes/lttng.o wrapper/trace-clock.o \
+ lttng-tracker-pid.o
obj-m += lttng-statedump.o
lttng-statedump-objs := lttng-statedump-impl.o wrapper/irqdesc.o \
* Disables tracing for a session (strong disable)
* LTTNG_KERNEL_METADATA
* Returns a LTTng metadata file descriptor
+ * LTTNG_KERNEL_SESSION_TRACK_PID
+ * Add PID to session tracker
+ * LTTNG_KERNEL_SESSION_UNTRACK_PID
+ * Remove PID from session tracker
*
* The returned channel will be deleted when its file descriptor is closed.
*/
return lttng_abi_create_channel(file, &chan_param,
METADATA_CHANNEL);
}
+ case LTTNG_KERNEL_SESSION_TRACK_PID:
+ return lttng_session_track_pid(session, (int) arg);
+ case LTTNG_KERNEL_SESSION_UNTRACK_PID:
+ return lttng_session_untrack_pid(session, (int) arg);
default:
return -ENOIOCTLCMD;
}
_IOW(0xF6, 0x55, struct lttng_kernel_channel)
#define LTTNG_KERNEL_SESSION_START _IO(0xF6, 0x56)
#define LTTNG_KERNEL_SESSION_STOP _IO(0xF6, 0x57)
+#define LTTNG_KERNEL_SESSION_TRACK_PID \
+ _IOR(0xF6, 0x58, int32_t)
+#define LTTNG_KERNEL_SESSION_UNTRACK_PID \
+ _IOR(0xF6, 0x59, int32_t)
/* Channel FD ioctl */
#define LTTNG_KERNEL_STREAM _IO(0xF6, 0x62)
}
list_for_each_entry(metadata_stream, &session->metadata_cache->metadata_stream, list)
_lttng_metadata_channel_hangup(metadata_stream);
+ if (session->pid_tracker)
+ lttng_pid_tracker_destroy(session->pid_tracker);
kref_put(&session->metadata_cache->refcount, metadata_cache_destroy);
list_del(&session->list);
mutex_unlock(&sessions_mutex);
kmem_cache_free(event_cache, event);
}
+int lttng_session_track_pid(struct lttng_session *session, int pid)
+{
+ int ret;
+
+ if (pid < -1)
+ return -EINVAL;
+ mutex_lock(&sessions_mutex);
+ if (pid == -1) {
+ /* track all pids: destroy tracker. */
+ if (session->pid_tracker) {
+ struct lttng_pid_tracker *lpf;
+
+ lpf = session->pid_tracker;
+ rcu_assign_pointer(session->pid_tracker, NULL);
+ synchronize_trace();
+ lttng_pid_tracker_destroy(lpf);
+ }
+ ret = 0;
+ } else {
+ if (!session->pid_tracker) {
+ struct lttng_pid_tracker *lpf;
+
+ lpf = lttng_pid_tracker_create();
+ if (!lpf) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+ ret = lttng_pid_tracker_add(lpf, pid);
+ rcu_assign_pointer(session->pid_tracker, lpf);
+ } else {
+ ret = lttng_pid_tracker_add(session->pid_tracker, pid);
+ }
+ }
+unlock:
+ mutex_unlock(&sessions_mutex);
+ return ret;
+}
+
+int lttng_session_untrack_pid(struct lttng_session *session, int pid)
+{
+ int ret;
+
+ if (pid < -1)
+ return -EINVAL;
+ mutex_lock(&sessions_mutex);
+ if (pid == -1) {
+ /* untrack all pids: replace by empty tracker. */
+ struct lttng_pid_tracker *old_lpf = session->pid_tracker;
+ struct lttng_pid_tracker *lpf;
+
+ lpf = lttng_pid_tracker_create();
+ if (!lpf) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+ rcu_assign_pointer(session->pid_tracker, lpf);
+ synchronize_trace();
+ if (old_lpf)
+ lttng_pid_tracker_destroy(old_lpf);
+ ret = 0;
+ } else {
+ if (!session->pid_tracker) {
+ ret = -ENOENT;
+ goto unlock;
+ }
+ ret = lttng_pid_tracker_del(session->pid_tracker, pid);
+ }
+unlock:
+ mutex_unlock(&sessions_mutex);
+ return ret;
+}
+
/*
* Serialize at most one packet worth of metadata into a metadata
* channel.
struct mutex lock;
};
+
+/*
+ * struct lttng_pid_tracker declared in header due to deferencing of *v
+ * in RCU_INITIALIZER(v).
+ */
+#define LTTNG_PID_HASH_BITS 6
+#define LTTNG_PID_TABLE_SIZE (1 << LTTNG_PID_HASH_BITS)
+
+struct lttng_pid_tracker {
+ struct hlist_head pid_hash[LTTNG_PID_TABLE_SIZE];
+};
+
struct lttng_session {
int active; /* Is trace session active ? */
int been_active; /* Has trace session been active ? */
unsigned int free_chan_id; /* Next chan ID to allocate */
uuid_le uuid; /* Trace session unique ID */
struct lttng_metadata_cache *metadata_cache;
+ struct lttng_pid_tracker *pid_tracker;
unsigned int metadata_dumped:1;
};
int lttng_metadata_output_channel(struct lttng_metadata_stream *stream,
struct channel *chan);
+struct lttng_pid_tracker *lttng_pid_tracker_create(void);
+void lttng_pid_tracker_destroy(struct lttng_pid_tracker *lpf);
+bool lttng_pid_tracker_lookup(struct lttng_pid_tracker *lpf, int pid);
+int lttng_pid_tracker_add(struct lttng_pid_tracker *lpf, int pid);
+int lttng_pid_tracker_del(struct lttng_pid_tracker *lpf, int pid);
+
+int lttng_session_track_pid(struct lttng_session *session, int pid);
+int lttng_session_untrack_pid(struct lttng_session *session, int pid);
+
#if defined(CONFIG_HAVE_SYSCALL_TRACEPOINTS)
int lttng_syscalls_register(struct lttng_channel *chan, void *filter);
int lttng_syscalls_unregister(struct lttng_channel *chan);
--- /dev/null
+/*
+ * lttng-tracker-pid.c
+ *
+ * LTTng Process ID trackering.
+ *
+ * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/seq_file.h>
+#include <linux/stringify.h>
+#include <linux/rculist.h>
+#include <linux/hash.h>
+#include <linux/rcupdate.h>
+
+#include "wrapper/tracepoint.h"
+#include "lttng-events.h"
+
+/*
+ * Hash table is allocated and freed when there are no possible
+ * concurrent lookups (ensured by the alloc/free caller). However,
+ * there can be concurrent RCU lookups vs add/del operations.
+ *
+ * Concurrent updates of the PID hash table are forbidden: the caller
+ * must ensure mutual exclusion. This is currently done by holding the
+ * sessions_mutex across calls to create, destroy, add, and del
+ * functions of this API.
+ */
+struct lttng_pid_hash_node {
+ struct hlist_node hlist;
+ int pid;
+};
+
+/*
+ * Lookup performed from RCU read-side critical section (RCU sched),
+ * protected by preemption off at the tracepoint call site.
+ * Return 1 if found, 0 if not found.
+ */
+bool lttng_pid_tracker_lookup(struct lttng_pid_tracker *lpf, int pid)
+{
+ struct hlist_head *head;
+ struct lttng_pid_hash_node *e;
+ uint32_t hash = hash_32(pid, 32);
+
+ head = &lpf->pid_hash[hash & (LTTNG_PID_TABLE_SIZE - 1)];
+ hlist_for_each_entry_rcu_notrace(e, head, hlist) {
+ if (pid == e->pid)
+ return 1; /* Found */
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_pid_tracker_lookup);
+
+/*
+ * Tracker add and del operations support concurrent RCU lookups.
+ */
+int lttng_pid_tracker_add(struct lttng_pid_tracker *lpf, int pid)
+{
+ struct hlist_head *head;
+ struct lttng_pid_hash_node *e;
+ uint32_t hash = hash_32(pid, 32);
+
+ head = &lpf->pid_hash[hash & (LTTNG_PID_TABLE_SIZE - 1)];
+ hlist_for_each_entry(e, head, hlist) {
+ if (pid == e->pid)
+ return -EEXIST;
+ }
+ e = kmalloc(sizeof(struct lttng_pid_hash_node), GFP_KERNEL);
+ if (!e)
+ return -ENOMEM;
+ e->pid = pid;
+ hlist_add_head_rcu(&e->hlist, head);
+ return 0;
+}
+
+static
+void pid_tracker_del_node_rcu(struct lttng_pid_hash_node *e)
+{
+ hlist_del_rcu(&e->hlist);
+ /*
+ * We choose to use a heavyweight synchronize on removal here,
+ * since removal of a PID from the tracker mask is a rare
+ * operation, and we don't want to use more cache lines than
+ * what we really need when doing the PID lookups, so we don't
+ * want to afford adding a rcu_head field to those pid hash
+ * node.
+ */
+ synchronize_trace();
+ kfree(e);
+}
+
+/*
+ * This removal is only used on destroy, so it does not need to support
+ * concurrent RCU lookups.
+ */
+static
+void pid_tracker_del_node(struct lttng_pid_hash_node *e)
+{
+ hlist_del(&e->hlist);
+ kfree(e);
+}
+
+int lttng_pid_tracker_del(struct lttng_pid_tracker *lpf, int pid)
+{
+ struct hlist_head *head;
+ struct lttng_pid_hash_node *e;
+ uint32_t hash = hash_32(pid, 32);
+
+ head = &lpf->pid_hash[hash & (LTTNG_PID_TABLE_SIZE - 1)];
+ /*
+ * No need of _safe iteration, because we stop traversal as soon
+ * as we remove the entry.
+ */
+ hlist_for_each_entry(e, head, hlist) {
+ if (pid == e->pid) {
+ pid_tracker_del_node_rcu(e);
+ return 0;
+ }
+ }
+ return -ENOENT; /* Not found */
+}
+
+struct lttng_pid_tracker *lttng_pid_tracker_create(void)
+{
+ return kzalloc(sizeof(struct lttng_pid_tracker), GFP_KERNEL);
+}
+
+void lttng_pid_tracker_destroy(struct lttng_pid_tracker *lpf)
+{
+ int i;
+
+ for (i = 0; i < LTTNG_PID_TABLE_SIZE; i++) {
+ struct hlist_head *head = &lpf->pid_hash[i];
+ struct lttng_pid_hash_node *e;
+ struct hlist_node *tmp;
+
+ hlist_for_each_entry_safe(e, tmp, head, hlist)
+ pid_tracker_del_node(e);
+ }
+ kfree(lpf);
+}
struct probe_local_vars { _locvar }; \
struct lttng_event *__event = __data; \
struct lttng_channel *__chan = __event->chan; \
+ struct lttng_session *__session = __chan->session; \
struct lib_ring_buffer_ctx __ctx; \
size_t __event_len, __event_align; \
size_t __dynamic_len_idx __attribute__((unused)) = 0; \
struct probe_local_vars __tp_locvar; \
struct probe_local_vars *tp_locvar __attribute__((unused)) = \
&__tp_locvar; \
+ struct lttng_pid_tracker *__lpf; \
\
- if (!_TP_SESSION_CHECK(session, __chan->session)) \
+ if (!_TP_SESSION_CHECK(session, __session)) \
return; \
- if (unlikely(!ACCESS_ONCE(__chan->session->active))) \
+ if (unlikely(!ACCESS_ONCE(__session->active))) \
return; \
if (unlikely(!ACCESS_ONCE(__chan->enabled))) \
return; \
if (unlikely(!ACCESS_ONCE(__event->enabled))) \
return; \
+ __lpf = rcu_dereference(__session->pid_tracker); \
+ if (__lpf && likely(!lttng_pid_tracker_lookup(__lpf, current->pid))) \
+ return; \
_code \
__event_len = __event_get_size__##_name(__dynamic_len, tp_locvar, \
_args); \
struct probe_local_vars { _locvar }; \
struct lttng_event *__event = __data; \
struct lttng_channel *__chan = __event->chan; \
+ struct lttng_session *__session = __chan->session; \
struct lib_ring_buffer_ctx __ctx; \
size_t __event_len, __event_align; \
size_t __dynamic_len_idx __attribute__((unused)) = 0; \
struct probe_local_vars __tp_locvar; \
struct probe_local_vars *tp_locvar __attribute__((unused)) = \
&__tp_locvar; \
+ struct lttng_pid_tracker *__lpf; \
\
- if (!_TP_SESSION_CHECK(session, __chan->session)) \
+ if (!_TP_SESSION_CHECK(session, __session)) \
return; \
- if (unlikely(!ACCESS_ONCE(__chan->session->active))) \
+ if (unlikely(!ACCESS_ONCE(__session->active))) \
return; \
if (unlikely(!ACCESS_ONCE(__chan->enabled))) \
return; \
if (unlikely(!ACCESS_ONCE(__event->enabled))) \
return; \
+ __lpf = rcu_dereference(__session->pid_tracker); \
+ if (__lpf && likely(!lttng_pid_tracker_lookup(__lpf, current->pid))) \
+ return; \
_code \
__event_len = __event_get_size__##_name(__dynamic_len, tp_locvar); \
__event_align = __event_get_align__##_name(tp_locvar); \
projects / lttng-modules.git / commitdiff
