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ring-buffer: Add ring_buffer_wake_waiters()

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commit 7e9fbbb1b7 upstream.

On closing of a file that represents a ring buffer or flushing the file,
there may be waiters on the ring buffer that needs to be woken up and exit
the ring_buffer_wait() function.

Add ring_buffer_wake_waiters() to wake up the waiters on the ring buffer
and allow them to exit the wait loop.

Link: https://lkml.kernel.org/r/20220928133938.28dc2c27@gandalf.local.home

Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: 15693458c4 ("tracing/ring-buffer: Move poll wake ups into ring buffer code")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Steven Rostedt (Google) 2022-09-28 13:39:38 -04:00 committed by Greg Kroah-Hartman
parent 5201dd81ae
commit be60f698c2
2 changed files with 40 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/ring_buffer.h
View File

@ -101,7 +101,7 @@ __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);
void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu);
#define RING_BUFFER_ALL_CPUS -1

39
kernel/trace/ring_buffer.c
View File

@ -405,6 +405,7 @@ struct rb_irq_work {
struct irq_work work;
wait_queue_head_t waiters;
wait_queue_head_t full_waiters;
long wait_index;
bool waiters_pending;
bool full_waiters_pending;
bool wakeup_full;
@ -888,6 +889,37 @@ static void rb_wake_up_waiters(struct irq_work *work)
}
}
/**
* ring_buffer_wake_waiters - wake up any waiters on this ring buffer
* @buffer: The ring buffer to wake waiters on
*
* In the case of a file that represents a ring buffer is closing,
* it is prudent to wake up any waiters that are on this.
*/
void ring_buffer_wake_waiters(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct rb_irq_work *rbwork;
if (cpu == RING_BUFFER_ALL_CPUS) {
/* Wake up individual ones too. One level recursion */
for_each_buffer_cpu(buffer, cpu)
ring_buffer_wake_waiters(buffer, cpu);
rbwork = &buffer->irq_work;
} else {
cpu_buffer = buffer->buffers[cpu];
rbwork = &cpu_buffer->irq_work;
}
rbwork->wait_index++;
/* make sure the waiters see the new index */
smp_wmb();
rb_wake_up_waiters(&rbwork->work);
}
/**
* ring_buffer_wait - wait for input to the ring buffer
* @buffer: buffer to wait on
@ -903,6 +935,7 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
struct ring_buffer_per_cpu *cpu_buffer;
DEFINE_WAIT(wait);
struct rb_irq_work *work;
long wait_index;
int ret = 0;
/*
@ -921,6 +954,7 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
work = &cpu_buffer->irq_work;
}
wait_index = READ_ONCE(work->wait_index);
while (true) {
if (full)
@ -985,6 +1019,11 @@ int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full)
}
schedule();
/* Make sure to see the new wait index */
smp_rmb();
if (wait_index != work->wait_index)
break;
}
if (full)