livepatch: Use static buffer for debugging messages under rq lock

The err_buf array uses 128 bytes of stack space.  Move it off the stack
by making it static.  It's safe to use a shared buffer because
klp_try_switch_task() is called under klp_mutex.

Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index c53370d596be..0a3889c4f617 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -293,11 +293,11 @@ static int klp_check_stack(struct task_struct *task, char *err_buf)
  */
 static bool klp_try_switch_task(struct task_struct *task)
 {
+        static char err_buf[STACK_ERR_BUF_SIZE];
         struct rq *rq;
         struct rq_flags flags;
         int ret;
         bool success = false;
-        char err_buf[STACK_ERR_BUF_SIZE];
 
         err_buf[0] = '\0';
 
@@ -340,7 +340,6 @@ done:
                 pr_debug("%s", err_buf);
 
         return success;
-
 }
 
 /*