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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2008-08-08 21:47:09 +0200
committerIngo Molnar <mingo@elte.hu>2008-08-11 13:46:53 +0200
commitb845b517b5e3706a3729f6ea83b88ab85f0725b0 (patch)
tree4311e4c2e6c3fdbdbe89149d1501944294186455 /kernel/printk.c
parent796aadeb1b2db9b5d463946766c5bbfd7717158c (diff)
downloadlinux-b845b517b5e3706a3729f6ea83b88ab85f0725b0.tar.bz2
printk: robustify printk
Avoid deadlocks against rq->lock and xtime_lock by deferring the klogd wakeup by polling from the timer tick. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/printk.c')
-rw-r--r--kernel/printk.c19
1 files changed, 17 insertions, 2 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index b51b1567bb55..655cc2ca10cc 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -982,10 +982,25 @@ int is_console_locked(void)
return console_locked;
}
-void wake_up_klogd(void)
+static DEFINE_PER_CPU(int, printk_pending);
+
+void printk_tick(void)
{
- if (!oops_in_progress && waitqueue_active(&log_wait))
+ if (__get_cpu_var(printk_pending)) {
+ __get_cpu_var(printk_pending) = 0;
wake_up_interruptible(&log_wait);
+ }
+}
+
+int printk_needs_cpu(int cpu)
+{
+ return per_cpu(printk_pending, cpu);
+}
+
+void wake_up_klogd(void)
+{
+ if (waitqueue_active(&log_wait))
+ __get_cpu_var(printk_pending) = 1;
}
/**