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authorGaurav Kohli <gkohli@codeaurora.org>2020-10-06 15:03:53 +0530
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2020-10-15 12:01:13 -0400
commitbbeb97464eefc65f506084fd9f18f21653e01137 (patch)
tree30bf973e9b25922c537d3237a66d03fab42b7ce2 /kernel
parent6d9bd139455d9d40fec8c242985996468b34180c (diff)
downloadlinux-bbeb97464eefc65f506084fd9f18f21653e01137.tar.bz2
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/trace/ring_buffer.c10
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);
}
/**