path: root/kernel/trace
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authorLinus Torvalds <torvalds@linux-foundation.org>2021-08-17 09:47:18 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2021-08-17 09:47:18 -1000
commit614cb2751d3150850d459bee596c397f344a7936 (patch)
tree1f1903908a6f90b49c80614e12f3e55507ee03f0 /kernel/trace
parent794c7931a2428a656551f2179e6a093233a6e0aa (diff)
parent6c34df6f350df9579ce99d887a2b5fa14cc13b32 (diff)
Merge tag 'trace-v5.14-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fix from Steven Rostedt: "Limit the shooting in the foot of tp_printk The "tp_printk" option redirects the trace event output to printk at boot up. This is useful when a machine crashes before boot where the trace events can not be retrieved by the in kernel ring buffer. But it can be "dangerous" because trace events can be located in high frequency locations such as interrupts and the scheduler, where a printk can slow it down that it live locks the machine (because by the time the printk finishes, the next event is triggered). Thus tp_printk must be used with care. It was discovered that the filter logic to trace events does not apply to the tp_printk events. This can cause a surprise and live lock when the user expects it to be filtered to limit the amount of events printed to the console when in fact it still prints everything" * tag 'trace-v5.14-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Apply trace filters on all output channels
Diffstat (limited to 'kernel/trace')
2 files changed, 15 insertions, 35 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 33899a71fdc1..a1adb29ef5c1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2897,14 +2897,26 @@ int tracepoint_printk_sysctl(struct ctl_table *table, int write,
void trace_event_buffer_commit(struct trace_event_buffer *fbuffer)
+ enum event_trigger_type tt = ETT_NONE;
+ struct trace_event_file *file = fbuffer->trace_file;
+ if (__event_trigger_test_discard(file, fbuffer->buffer, fbuffer->event,
+ fbuffer->entry, &tt))
+ goto discard;
if (static_key_false(&tracepoint_printk_key.key))
if (static_branch_unlikely(&trace_event_exports_enabled))
ftrace_exports(fbuffer->event, TRACE_EXPORT_EVENT);
- event_trigger_unlock_commit_regs(fbuffer->trace_file, fbuffer->buffer,
- fbuffer->event, fbuffer->entry,
- fbuffer->trace_ctx, fbuffer->regs);
+ trace_buffer_unlock_commit_regs(file->tr, fbuffer->buffer,
+ fbuffer->event, fbuffer->trace_ctx, fbuffer->regs);
+ if (tt)
+ event_triggers_post_call(file, tt);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index a180abf76d4e..4a0e693000c6 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1389,38 +1389,6 @@ event_trigger_unlock_commit(struct trace_event_file *file,
event_triggers_post_call(file, tt);
- * event_trigger_unlock_commit_regs - handle triggers and finish event commit
- * @file: The file pointer associated with the event
- * @buffer: The ring buffer that the event is being written to
- * @event: The event meta data in the ring buffer
- * @entry: The event itself
- * @trace_ctx: The tracing context flags.
- *
- * This is a helper function to handle triggers that require data
- * from the event itself. It also tests the event against filters and
- * if the event is soft disabled and should be discarded.
- *
- * Same as event_trigger_unlock_commit() but calls
- * trace_buffer_unlock_commit_regs() instead of trace_buffer_unlock_commit().
- */
-static inline void
-event_trigger_unlock_commit_regs(struct trace_event_file *file,
- struct trace_buffer *buffer,
- struct ring_buffer_event *event,
- void *entry, unsigned int trace_ctx,
- struct pt_regs *regs)
- enum event_trigger_type tt = ETT_NONE;
- if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
- trace_buffer_unlock_commit_regs(file->tr, buffer, event,
- trace_ctx, regs);
- if (tt)
- event_triggers_post_call(file, tt);
#define FILTER_PRED_INVALID ((unsigned short)-1)
#define FILTER_PRED_IS_RIGHT (1 << 15)
#define FILTER_PRED_FOLD (1 << 15)

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