From: Steven Rostedt 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 --- 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 2e99dba..969f7cb 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; } -- 1.6.3.1 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/