There is a problem in the linux-6.5 when I execute the following
command:
$ perf ftrace -t irqsoff
failed to open trace_pipe
At the same time, when I open this file, the same error occurs.
Therefore, after carefully looking at the code, the open function of
'trace_pipe' returns -EBUSY in open_pipe_on_cpu() because no clearing
operation was performed when 'trace_array->pipe_cpumask' was allocated.
With this patch, Use zalloc_cpumask_var() to ensure that
'trace_array->pipe_cpumask' is reset to 0 when allocated.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: c2489bb7e6be ("tracing: Introduce pipe_cpumask to avoid race on trace_pipes")
Signed-off-by: Chuang Wang <nashuiliang@xxxxxxxxx>
---
kernel/trace/trace.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index d8233d34b5a0..c0b8a72f3466 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9461,7 +9461,7 @@ 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;
@@ -10406,7 +10406,7 @@ __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 */
--
2.39.2
