mainline inclusion from mainline-v6.5 commit b71645d6af10196c46cbe3732de2ea7d36b3ff6d category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7SHZP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...

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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: Zheng Yejian zhengyejian1@huawei.com --- kernel/trace/trace.c | 6 ++++++ 1 file changed, 6 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 1e1781ace916..fab69081d6d8 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4249,11 +4249,17 @@ tracing_cpumask_write(struct file *filp, const char __user *ubuf, !cpumask_test_cpu(cpu, tracing_cpumask_new)) { atomic_inc(&per_cpu_ptr(tr->trace_buffer.data, cpu)->disabled); ring_buffer_record_disable_cpu(tr->trace_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->trace_buffer.data, cpu)->disabled); ring_buffer_record_enable_cpu(tr->trace_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);