From 722773afd83209d4088d30946bc274f547528a0b Mon Sep 17 00:00:00 2001 From: Rik van Riel <riel@redhat.com> Date: Fri, 6 Jun 2014 14:38:14 -0700 Subject: [PATCH] sysrq,rcu: suppress RCU stall warnings while sysrq runs Some sysrq handlers can run for a long time, because they dump a lot of data onto a serial console. Having RCU stall warnings pop up in the middle of them only makes the problem worse. This patch temporarily disables RCU stall warnings while a sysrq request is handled. Signed-off-by: Rik van Riel <riel@redhat.com> Suggested-by: Paul McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Madper Xie <cxie@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> --- drivers/tty/sysrq.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/tty/sysrq.c b/drivers/tty/sysrq.c index 7430e87d7352..454b65898e2c 100644 --- a/drivers/tty/sysrq.c +++ b/drivers/tty/sysrq.c @@ -46,6 +46,7 @@ #include <linux/jiffies.h> #include <linux/syscalls.h> #include <linux/of.h> +#include <linux/rcupdate.h> #include <asm/ptrace.h> #include <asm/irq_regs.h> @@ -511,6 +512,7 @@ void __handle_sysrq(int key, bool check_mask) int orig_log_level; int i; + rcu_sysrq_start(); rcu_read_lock(); /* * Raise the apparent loglevel to maximum so that the sysrq header @@ -554,6 +556,7 @@ void __handle_sysrq(int key, bool check_mask) console_loglevel = orig_log_level; } rcu_read_unlock(); + rcu_sysrq_end(); } void handle_sysrq(int key) -- GitLab