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| author | Steven Rostedt <srostedt@redhat.com> | 2009-06-17 00:39:43 -0400 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2009-06-17 14:16:23 -0400 |
| commit | d47882078f05c2cb46b85f1e12a58ed9315b9d63 (patch) | |
| tree | ad10f2172384d2112b6e8136b9981a0eb813539b /kernel/trace | |
| parent | 5f78abeebbf0a80975d719e11374535ca15396cb (diff) | |
| download | linux-d47882078f05c2cb46b85f1e12a58ed9315b9d63.tar.gz linux-d47882078f05c2cb46b85f1e12a58ed9315b9d63.tar.bz2 linux-d47882078f05c2cb46b85f1e12a58ed9315b9d63.zip | |
ring-buffer: add locks around rb_per_cpu_empty
The checking of whether the buffer is empty or not needs to be serialized
among the readers. Add the reader spin lock around it.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 2e99dba6dc48..969f7cbe8e93 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2756,12 +2756,17 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset); int ring_buffer_empty(struct ring_buffer *buffer) { struct ring_buffer_per_cpu *cpu_buffer; + unsigned long flags; int cpu; + int ret; /* yes this is racy, but if you don't like the race, lock the buffer */ for_each_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; - if (!rb_per_cpu_empty(cpu_buffer)) + spin_lock_irqsave(&cpu_buffer->reader_lock, flags); + ret = rb_per_cpu_empty(cpu_buffer); + spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); + if (!ret) return 0; } @@ -2777,14 +2782,16 @@ EXPORT_SYMBOL_GPL(ring_buffer_empty); int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu) { struct ring_buffer_per_cpu *cpu_buffer; + unsigned long flags; int ret; if (!cpumask_test_cpu(cpu, buffer->cpumask)) return 1; cpu_buffer = buffer->buffers[cpu]; + spin_lock_irqsave(&cpu_buffer->reader_lock, flags); ret = rb_per_cpu_empty(cpu_buffer); - + spin_unlock_irqrestore(&cpu_buffer->reader_lock, flags); return ret; } |