From: Petr Mladek <pmladek@suse.com>
Date: Fri, 31 May 2019 09:41:47 +0200
Subject: livepatch: Use static buffer for debugging messages under rq lock
Git-commit: f36e664516b02c7f54bbd3094bab047d54bb5488
Patch-mainline: v5.3-rc1
References: bsc#1071995 fate#323487

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>
---
 kernel/livepatch/transition.c | 3 +--
 1 file changed, 1 insertion(+), 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 @@ static bool klp_try_switch_task(struct task_struct *task)
 		pr_debug("%s", err_buf);
 
 	return success;
-
 }
 
 /*