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-rw-r--r--kernel/trace/trace.c154
-rw-r--r--kernel/trace/trace.h19
-rw-r--r--kernel/trace/trace_events.c10
-rw-r--r--kernel/trace/trace_events_filter.c10
4 files changed, 185 insertions, 8 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index c09e8ff..8a4bd6b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -312,7 +312,7 @@ int call_filter_check_discard(struct trace_event_call *call, void *rec,
{
if (unlikely(call->flags & TRACE_EVENT_FL_FILTERED) &&
!filter_match_preds(call->filter, rec)) {
- ring_buffer_discard_commit(buffer, event);
+ __trace_event_discard_commit(buffer, event);
return 1;
}
@@ -1660,6 +1660,16 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
}
EXPORT_SYMBOL_GPL(tracing_generic_entry_update);
+static __always_inline void
+trace_event_setup(struct ring_buffer_event *event,
+ int type, unsigned long flags, int pc)
+{
+ struct trace_entry *ent = ring_buffer_event_data(event);
+
+ tracing_generic_entry_update(ent, flags, pc);
+ ent->type = type;
+}
+
struct ring_buffer_event *
trace_buffer_lock_reserve(struct ring_buffer *buffer,
int type,
@@ -1669,21 +1679,136 @@ trace_buffer_lock_reserve(struct ring_buffer *buffer,
struct ring_buffer_event *event;
event = ring_buffer_lock_reserve(buffer, len);
- if (event != NULL) {
- struct trace_entry *ent = ring_buffer_event_data(event);
+ if (event != NULL)
+ trace_event_setup(event, type, flags, pc);
+
+ return event;
+}
+
+DEFINE_PER_CPU(struct ring_buffer_event *, trace_buffered_event);
+DEFINE_PER_CPU(int, trace_buffered_event_cnt);
+static int trace_buffered_event_ref;
+
+/**
+ * trace_buffered_event_enable - enable buffering events
+ *
+ * When events are being filtered, it is quicker to use a temporary
+ * buffer to write the event data into if there's a likely chance
+ * that it will not be committed. The discard of the ring buffer
+ * is not as fast as committing, and is much slower than copying
+ * a commit.
+ *
+ * When an event is to be filtered, allocate per cpu buffers to
+ * write the event data into, and if the event is filtered and discarded
+ * it is simply dropped, otherwise, the entire data is to be committed
+ * in one shot.
+ */
+void trace_buffered_event_enable(void)
+{
+ struct ring_buffer_event *event;
+ struct page *page;
+ int cpu;
- tracing_generic_entry_update(ent, flags, pc);
- ent->type = type;
+ WARN_ON_ONCE(!mutex_is_locked(&event_mutex));
+
+ if (trace_buffered_event_ref++)
+ return;
+
+ for_each_tracing_cpu(cpu) {
+ page = alloc_pages_node(cpu_to_node(cpu),
+ GFP_KERNEL | __GFP_NORETRY, 0);
+ if (!page)
+ goto failed;
+
+ event = page_address(page);
+ memset(event, 0, sizeof(*event));
+
+ per_cpu(trace_buffered_event, cpu) = event;
+
+ preempt_disable();
+ if (cpu == smp_processor_id() &&
+ this_cpu_read(trace_buffered_event) !=
+ per_cpu(trace_buffered_event, cpu))
+ WARN_ON_ONCE(1);
+ preempt_enable();
}
- return event;
+ return;
+ failed:
+ trace_buffered_event_disable();
+}
+
+static void enable_trace_buffered_event(void *data)
+{
+ /* Probably not needed, but do it anyway */
+ smp_rmb();
+ this_cpu_dec(trace_buffered_event_cnt);
+}
+
+static void disable_trace_buffered_event(void *data)
+{
+ this_cpu_inc(trace_buffered_event_cnt);
+}
+
+/**
+ * trace_buffered_event_disable - disable buffering events
+ *
+ * When a filter is removed, it is faster to not use the buffered
+ * events, and to commit directly into the ring buffer. Free up
+ * the temp buffers when there are no more users. This requires
+ * special synchronization with current events.
+ */
+void trace_buffered_event_disable(void)
+{
+ int cpu;
+
+ WARN_ON_ONCE(!mutex_is_locked(&event_mutex));
+
+ if (WARN_ON_ONCE(!trace_buffered_event_ref))
+ return;
+
+ if (--trace_buffered_event_ref)
+ return;
+
+ preempt_disable();
+ /* For each CPU, set the buffer as used. */
+ smp_call_function_many(tracing_buffer_mask,
+ disable_trace_buffered_event, NULL, 1);
+ preempt_enable();
+
+ /* Wait for all current users to finish */
+ synchronize_sched();
+
+ for_each_tracing_cpu(cpu) {
+ free_page((unsigned long)per_cpu(trace_buffered_event, cpu));
+ per_cpu(trace_buffered_event, cpu) = NULL;
+ }
+ /*
+ * Make sure trace_buffered_event is NULL before clearing
+ * trace_buffered_event_cnt.
+ */
+ smp_wmb();
+
+ preempt_disable();
+ /* Do the work on each cpu */
+ smp_call_function_many(tracing_buffer_mask,
+ enable_trace_buffered_event, NULL, 1);
+ preempt_enable();
}
void
__buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event)
{
__this_cpu_write(trace_cmdline_save, true);
- ring_buffer_unlock_commit(buffer, event);
+
+ /* If this is the temp buffer, we need to commit fully */
+ if (this_cpu_read(trace_buffered_event) == event) {
+ /* Length is in event->array[0] */
+ ring_buffer_write(buffer, event->array[0], &event->array[1]);
+ /* Release the temp buffer */
+ this_cpu_dec(trace_buffered_event_cnt);
+ } else
+ ring_buffer_unlock_commit(buffer, event);
}
static struct ring_buffer *temp_buffer;
@@ -1695,8 +1820,23 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb,
unsigned long flags, int pc)
{
struct ring_buffer_event *entry;
+ int val;
*current_rb = trace_file->tr->trace_buffer.buffer;
+
+ if ((trace_file->flags &
+ (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) &&
+ (entry = this_cpu_read(trace_buffered_event))) {
+ /* Try to use the per cpu buffer first */
+ val = this_cpu_inc_return(trace_buffered_event_cnt);
+ if (val == 1) {
+ trace_event_setup(entry, type, flags, pc);
+ entry->array[0] = len;
+ return entry;
+ }
+ this_cpu_dec(trace_buffered_event_cnt);
+ }
+
entry = trace_buffer_lock_reserve(*current_rb,
type, len, flags, pc);
/*
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 10156a0..5167c36 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1083,6 +1083,23 @@ static inline void trace_buffer_unlock_commit(struct trace_array *tr,
trace_buffer_unlock_commit_regs(tr, buffer, event, flags, pc, NULL);
}
+DECLARE_PER_CPU(struct ring_buffer_event *, trace_buffered_event);
+DECLARE_PER_CPU(int, trace_buffered_event_cnt);
+void trace_buffered_event_disable(void);
+void trace_buffered_event_enable(void);
+
+static inline void
+__trace_event_discard_commit(struct ring_buffer *buffer,
+ struct ring_buffer_event *event)
+{
+ if (this_cpu_read(trace_buffered_event) == event) {
+ /* Simply release the temp buffer */
+ this_cpu_dec(trace_buffered_event_cnt);
+ return;
+ }
+ ring_buffer_discard_commit(buffer, event);
+}
+
/*
* Helper function for event_trigger_unlock_commit{_regs}().
* If there are event triggers attached to this event that requires
@@ -1111,7 +1128,7 @@ __event_trigger_test_discard(struct trace_event_file *file,
if (test_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags) ||
(unlikely(file->flags & EVENT_FILE_FL_FILTERED) &&
!filter_match_preds(file->filter, entry))) {
- ring_buffer_discard_commit(buffer, event);
+ __trace_event_discard_commit(buffer, event);
return true;
}
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index da1eeb6..4d00670 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -363,6 +363,7 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
{
struct trace_event_call *call = file->event_call;
struct trace_array *tr = file->tr;
+ unsigned long file_flags = file->flags;
int ret = 0;
int disable;
@@ -445,6 +446,15 @@ static int __ftrace_event_enable_disable(struct trace_event_file *file,
break;
}
+ /* Enable or disable use of trace_buffered_event */
+ if ((file_flags & EVENT_FILE_FL_SOFT_DISABLED) !=
+ (file->flags & EVENT_FILE_FL_SOFT_DISABLED)) {
+ if (file->flags & EVENT_FILE_FL_SOFT_DISABLED)
+ trace_buffered_event_enable();
+ else
+ trace_buffered_event_disable();
+ }
+
return ret;
}
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index d1d27bf..9daa9b3 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -823,7 +823,12 @@ static void __free_preds(struct event_filter *filter)
static void filter_disable(struct trace_event_file *file)
{
+ unsigned long old_flags = file->flags;
+
file->flags &= ~EVENT_FILE_FL_FILTERED;
+
+ if (old_flags != file->flags)
+ trace_buffered_event_disable();
}
static void __free_filter(struct event_filter *filter)
@@ -1698,7 +1703,12 @@ fail:
static inline void event_set_filtered_flag(struct trace_event_file *file)
{
+ unsigned long old_flags = file->flags;
+
file->flags |= EVENT_FILE_FL_FILTERED;
+
+ if (old_flags != file->flags)
+ trace_buffered_event_enable();
}
static inline void event_set_filter(struct trace_event_file *file,
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