From 42fb0a1e84ff525ebe560e2baf9451ab69127e2b Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Thu, 20 Oct 2022 23:14:27 -0400 Subject: tracing/ring-buffer: Have polling block on watermark Currently the way polling works on the ring buffer is broken. It will return immediately if there's any data in the ring buffer whereas a read will block until the watermark (defined by the tracefs buffer_percent file) is hit. That is, a select() or poll() will return as if there's data available, but then the following read will block. This is broken for the way select()s and poll()s are supposed to work. Have the polling on the ring buffer also block the same way reads and splice does on the ring buffer. Link: https://lkml.kernel.org/r/20221020231427.41be3f26@gandalf.local.home Cc: Linux Trace Kernel Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Primiano Tucci Cc: stable@vger.kernel.org Fixes: 1e0d6714aceb7 ("ring-buffer: Do not wake up a splice waiter when page is not full") Signed-off-by: Steven Rostedt (Google) --- include/linux/ring_buffer.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/ring_buffer.h') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 2504df9a0453..3c7d295746f6 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -100,7 +100,7 @@ __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *k int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full); __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu, - struct file *filp, poll_table *poll_table); + struct file *filp, poll_table *poll_table, int full); void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu); #define RING_BUFFER_ALL_CPUS -1 -- cgit v1.2.3 From 04aabc32fb677f91d676fd306bca1043805e78d5 Mon Sep 17 00:00:00 2001 From: Song Chen Date: Thu, 20 Oct 2022 22:06:51 +0800 Subject: ring_buffer: Remove unused "event" parameter After commit a389d86f7fd0 ("ring-buffer: Have nested events still record running time stamp"), the "event" parameter is no longer used in either ring_buffer_unlock_commit() or rb_commit(). Best to remove it. Link: https://lkml.kernel.org/r/1666274811-24138-1-git-send-email-chensong_2000@189.cn Signed-off-by: Song Chen Signed-off-by: Steven Rostedt (Google) --- include/linux/ring_buffer.h | 3 +-- kernel/trace/ring_buffer.c | 12 +++++------- kernel/trace/ring_buffer_benchmark.c | 2 +- kernel/trace/trace.c | 2 +- 4 files changed, 8 insertions(+), 11 deletions(-) (limited to 'include/linux/ring_buffer.h') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index 3c7d295746f6..782e14f62201 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -113,8 +113,7 @@ void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val); struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer, unsigned long length); -int ring_buffer_unlock_commit(struct trace_buffer *buffer, - struct ring_buffer_event *event); +int ring_buffer_unlock_commit(struct trace_buffer *buffer); int ring_buffer_write(struct trace_buffer *buffer, unsigned long length, void *data); diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b21bf14bae9b..843818ee4814 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -3180,8 +3180,7 @@ static inline void rb_event_discard(struct ring_buffer_event *event) event->time_delta = 1; } -static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer, - struct ring_buffer_event *event) +static void rb_commit(struct ring_buffer_per_cpu *cpu_buffer) { local_inc(&cpu_buffer->entries); rb_end_commit(cpu_buffer); @@ -3383,15 +3382,14 @@ void ring_buffer_nest_end(struct trace_buffer *buffer) * * Must be paired with ring_buffer_lock_reserve. */ -int ring_buffer_unlock_commit(struct trace_buffer *buffer, - struct ring_buffer_event *event) +int ring_buffer_unlock_commit(struct trace_buffer *buffer) { struct ring_buffer_per_cpu *cpu_buffer; int cpu = raw_smp_processor_id(); cpu_buffer = buffer->buffers[cpu]; - rb_commit(cpu_buffer, event); + rb_commit(cpu_buffer); rb_wakeups(buffer, cpu_buffer); @@ -3977,7 +3975,7 @@ int ring_buffer_write(struct trace_buffer *buffer, memcpy(body, data, length); - rb_commit(cpu_buffer, event); + rb_commit(cpu_buffer); rb_wakeups(buffer, cpu_buffer); @@ -5998,7 +5996,7 @@ static __init int rb_write_something(struct rb_test_data *data, bool nested) } out: - ring_buffer_unlock_commit(data->buffer, event); + ring_buffer_unlock_commit(data->buffer); return 0; } diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c index 78e576575b79..aef34673d79d 100644 --- a/kernel/trace/ring_buffer_benchmark.c +++ b/kernel/trace/ring_buffer_benchmark.c @@ -258,7 +258,7 @@ static void ring_buffer_producer(void) hit++; entry = ring_buffer_event_data(event); *entry = smp_processor_id(); - ring_buffer_unlock_commit(buffer, event); + ring_buffer_unlock_commit(buffer); } } end_time = ktime_get(); diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 5cfc95a52bc3..5c97dbef741b 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -999,7 +999,7 @@ __buffer_unlock_commit(struct trace_buffer *buffer, struct ring_buffer_event *ev /* ring_buffer_unlock_commit() enables preemption */ preempt_enable_notrace(); } else - ring_buffer_unlock_commit(buffer, event); + ring_buffer_unlock_commit(buffer); } /** -- cgit v1.2.3