diff options
| author | Gaurav Kohli | 2020-10-06 15:03:53 +0530 |
|---|---|---|
| committer | Steven Rostedt (VMware) | 2020-10-15 12:01:13 -0400 |
| commit | bbeb97464eefc65f506084fd9f18f21653e01137 (patch) | |
| tree | 30bf973e9b25922c537d3237a66d03fab42b7ce2 | |
| parent | 6d9bd139455d9d40fec8c242985996468b34180c (diff) | |
tracing: Fix race in trace_open and buffer resize call
Below race can come, if trace_open and resize of
cpu buffer is running parallely on different cpus
CPUX CPUY
ring_buffer_resize
atomic_read(&buffer->resize_disabled)
tracing_open
tracing_reset_online_cpus
ring_buffer_reset_cpu
rb_reset_cpu
rb_update_pages
remove/insert pages
resetting pointer
This race can cause data abort or some times infinte loop in
rb_remove_pages and rb_insert_pages while checking pages
for sanity.
Take buffer lock to fix this.
Link: https://lkml.kernel.org/r/1601976833-24377-1-git-send-email-gkohli@codeaurora.org
Cc: stable@vger.kernel.org
Fixes: b23d7a5f4a07a ("ring-buffer: speed up buffer resets by avoiding synchronize_rcu for each CPU")
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
| -rw-r--r-- | kernel/trace/ring_buffer.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 93ef0ab6ea20..15bf28b13e50 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -4866,6 +4866,9 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu) if (!cpumask_test_cpu(cpu, buffer->cpumask)) return; + /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); + atomic_inc(&cpu_buffer->resize_disabled); atomic_inc(&cpu_buffer->record_disabled); @@ -4876,6 +4879,8 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu) atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); + + mutex_unlock(&buffer->mutex); } EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu); @@ -4889,6 +4894,9 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) struct ring_buffer_per_cpu *cpu_buffer; int cpu; + /* prevent another thread from changing buffer sizes */ + mutex_lock(&buffer->mutex); + for_each_online_buffer_cpu(buffer, cpu) { cpu_buffer = buffer->buffers[cpu]; @@ -4907,6 +4915,8 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer) atomic_dec(&cpu_buffer->record_disabled); atomic_dec(&cpu_buffer->resize_disabled); } + + mutex_unlock(&buffer->mutex); } /** |