linux-kernel - [PATCH 3.4 05/24] printk: Fix scheduling-while-atomic problem in console_cpu

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Date:	Tue, 18 Feb 2014 14:46:52 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Guillaume Morin <guillaume@...infr.org>
Subject: [PATCH 3.4 05/24] printk: Fix scheduling-while-atomic problem in console_cpu_notify()

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>

commit 85eae82a0855d49852b87deac8653e4ebc8b291f upstream.

The console_cpu_notify() function runs with interrupts disabled in the
CPU_DYING case.  It therefore cannot block, for example, as will happen
when it calls console_lock().  Therefore, remove the CPU_DYING leg of
the switch statement to avoid this problem.

Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Guillaume Morin <guillaume@...infr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/printk.c |    1 -
 1 file changed, 1 deletion(-)

--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1172,7 +1172,6 @@ static int __cpuinit console_cpu_notify(
 	switch (action) {
 	case CPU_ONLINE:
 	case CPU_DEAD:
-	case CPU_DYING:
 	case CPU_DOWN_FAILED:
 	case CPU_UP_CANCELED:
 		console_lock();

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