diff options
| author | Zheng Yejian | 2023-08-05 11:38:15 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2023-08-30 16:11:00 +0200 |
| commit | 7d0c2b0de2dbf086373049ac9bf45b9ae7f421bb (patch) | |
| tree | e0a02a2f07efce1c31b828a405bb785c8e996ca2 /kernel | |
| parent | 7e862cce34916458bf6af954d198cce103c1e13f (diff) | |
tracing: Fix cpu buffers unavailable due to 'record_disabled' missed
[ Upstream commit b71645d6af10196c46cbe3732de2ea7d36b3ff6d ]
Trace ring buffer can no longer record anything after executing
following commands at the shell prompt:
# cd /sys/kernel/tracing
# cat tracing_cpumask
fff
# echo 0 > tracing_cpumask
# echo 1 > snapshot
# echo fff > tracing_cpumask
# echo 1 > tracing_on
# echo "hello world" > trace_marker
-bash: echo: write error: Bad file descriptor
The root cause is that:
1. After `echo 0 > tracing_cpumask`, 'record_disabled' of cpu buffers
in 'tr->array_buffer.buffer' became 1 (see tracing_set_cpumask());
2. After `echo 1 > snapshot`, 'tr->array_buffer.buffer' is swapped
with 'tr->max_buffer.buffer', then the 'record_disabled' became 0
(see update_max_tr());
3. After `echo fff > tracing_cpumask`, the 'record_disabled' become -1;
Then array_buffer and max_buffer are both unavailable due to value of
'record_disabled' is not 0.
To fix it, enable or disable both array_buffer and max_buffer at the same
time in tracing_set_cpumask().
Link: https://lkml.kernel.org/r/20230805033816.3284594-2-zhengyejian1@huawei.com
Cc: <mhiramat@kernel.org>
Cc: <vnagarnaik@google.com>
Cc: <shuah@kernel.org>
Fixes: 71babb2705e2 ("tracing: change CPU ring buffer state from tracing_cpumask")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/trace/trace.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index af33c5a4166d..d56dcd78452c 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5189,11 +5189,17 @@ int tracing_set_cpumask(struct trace_array *tr, !cpumask_test_cpu(cpu, tracing_cpumask_new)) { atomic_inc(&per_cpu_ptr(tr->array_buffer.data, cpu)->disabled); ring_buffer_record_disable_cpu(tr->array_buffer.buffer, cpu); +#ifdef CONFIG_TRACER_MAX_TRACE + ring_buffer_record_disable_cpu(tr->max_buffer.buffer, cpu); +#endif } if (!cpumask_test_cpu(cpu, tr->tracing_cpumask) && cpumask_test_cpu(cpu, tracing_cpumask_new)) { atomic_dec(&per_cpu_ptr(tr->array_buffer.data, cpu)->disabled); ring_buffer_record_enable_cpu(tr->array_buffer.buffer, cpu); +#ifdef CONFIG_TRACER_MAX_TRACE + ring_buffer_record_enable_cpu(tr->max_buffer.buffer, cpu); +#endif } } arch_spin_unlock(&tr->max_lock); |