From dfff6a94ddc3c45811b94714ac2f59a104b247ba Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt@goodmis.org>
Date: Mon, 6 Jan 2025 11:11:43 -0500
Subject: [PATCH] tracing: Fix using ret variable in tracing_set_tracer()
commit 22bec11a569983f39c6061cb82279e7de9e3bdfc upstream.
When the function tracing_set_tracer() switched over to using the guard()
infrastructure, it did not need to save the 'ret' variable and would just
return the value when an error arised, instead of setting ret and jumping
to an out label.
When CONFIG_TRACER_SNAPSHOT is enabled, it had code that expected the
"ret" variable to be initialized to zero and had set 'ret' while holding
an arch_spin_lock() (not used by guard), and then upon releasing the lock
it would check 'ret' and exit if set. But because ret was only set when an
error occurred while holding the locks, 'ret' would be used uninitialized
if there was no error. The code in the CONFIG_TRACER_SNAPSHOT block should
be self contain. Make sure 'ret' is also set when no error occurred.
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250106111143.2f90ff65@gandalf.local.home
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202412271654.nJVBuwmF-lkp@intel.com/
Fixes: d33b10c0c73ad ("tracing: Switch trace.c code over to use guard()")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/trace/trace.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 1142a7802bb60..ffe1422ab03f8 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6125,8 +6125,7 @@ int tracing_set_tracer(struct trace_array *tr, const char *buf)
if (t->use_max_tr) {
local_irq_disable();
arch_spin_lock(&tr->max_lock);
- if (tr->cond_snapshot)
- ret = -EBUSY;
+ ret = tr->cond_snapshot ? -EBUSY : 0;
arch_spin_unlock(&tr->max_lock);
local_irq_enable();
if (ret)
--
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