From: Brian Foster Date: Thu, 31 Aug 2023 12:55:00 +0000 (-0400) Subject: tracing: Zero the pipe cpumask on alloc to avoid spurious -EBUSY X-Git-Tag: v6.6.17~3930^2~22 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=3d07fa1dd19035eb0b13ae6697efd5caa9033e74;p=platform%2Fkernel%2Flinux-rpi.git tracing: Zero the pipe cpumask on alloc to avoid spurious -EBUSY The pipe cpumask used to serialize opens between the main and percpu trace pipes is not zeroed or initialized. This can result in spurious -EBUSY returns if underlying memory is not fully zeroed. This has been observed by immediate failure to read the main trace_pipe file on an otherwise newly booted and idle system: # cat /sys/kernel/debug/tracing/trace_pipe cat: /sys/kernel/debug/tracing/trace_pipe: Device or resource busy Zero the allocation of pipe_cpumask to avoid the problem. Link: https://lore.kernel.org/linux-trace-kernel/20230831125500.986862-1-bfoster@redhat.com Cc: stable@vger.kernel.org Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes") Reviewed-by: Zheng Yejian Reviewed-by: Masami Hiramatsu (Google) Signed-off-by: Brian Foster Signed-off-by: Steven Rostedt (Google) --- diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 23579fb..35783a7 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -9474,7 +9474,7 @@ static struct trace_array *trace_array_create(const char *name) if (!alloc_cpumask_var(&tr->tracing_cpumask, GFP_KERNEL)) goto out_free_tr; - if (!alloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) + if (!zalloc_cpumask_var(&tr->pipe_cpumask, GFP_KERNEL)) goto out_free_tr; tr->trace_flags = global_trace.trace_flags & ~ZEROED_TRACE_FLAGS; @@ -10419,7 +10419,7 @@ __init static int tracer_alloc_buffers(void) if (trace_create_savedcmd() < 0) goto out_free_temp_buffer; - if (!alloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) + if (!zalloc_cpumask_var(&global_trace.pipe_cpumask, GFP_KERNEL)) goto out_free_savedcmd; /* TODO: make the number of buffers hot pluggable with CPUS */