[PATCH 3.4 05/24] printk: Fix scheduling-while-atomic problem in console_cpu_notify()

Greg Kroah-Hartman
2014-02-18T23:29:51Z

From: "Paul E. McKenney" <paulmck@linux.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@linux.vnet.ibm.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Guillaume Morin <guillaume@morinfr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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();