Commit 722773af authored Jun 06, 2014 by Rik van Riel Committed by Linus Torvalds Jun 06, 2014

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>

parent 984d74a7

drivers/tty/sysrq.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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)

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