The patch titled
printk: robustify printk
has been removed from the -mm tree. Its filename was
printk-robustify-printk.patch
This patch was dropped because an updated version will be merged
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: printk: robustify printk
From: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Avoid deadlocks against rq->lock and xtime_lock by using RCU to defer
the klogd wakeup.
[akpm@xxxxxxxxxxxxxxxxxxxx: make klogd_wakeup_state static]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Acked-by: Steven Rostedt <srostedt@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk.c | 32 ++++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)
diff -puN kernel/printk.c~printk-robustify-printk kernel/printk.c
--- a/kernel/printk.c~printk-robustify-printk
+++ a/kernel/printk.c
@@ -32,6 +32,7 @@
#include <linux/security.h>
#include <linux/bootmem.h>
#include <linux/syscalls.h>
+#include <linux/rcupdate.h>
#include <asm/uaccess.h>
@@ -982,10 +983,37 @@ int is_console_locked(void)
return console_locked;
}
+struct klogd_wakeup_state {
+ struct rcu_head head;
+ int pending;
+};
+
+static DEFINE_PER_CPU(struct klogd_wakeup_state, kws);
+
+void __wake_up_klogd(struct rcu_head *head)
+{
+ struct klogd_wakeup_state *kws =
+ container_of(head, struct klogd_wakeup_state, head);
+
+ wake_up_interruptible(&log_wait);
+ kws->pending = 0;
+}
+
void wake_up_klogd(void)
{
- if (!oops_in_progress && waitqueue_active(&log_wait))
- wake_up_interruptible(&log_wait);
+ unsigned long flags;
+ struct klogd_wakeup_state *kws;
+
+ if (!waitqueue_active(&log_wait))
+ return;
+
+ local_irq_save(flags);
+ kws = &__get_cpu_var(kws);
+ if (!kws->pending) {
+ kws->pending = 1;
+ call_rcu(&kws->head, __wake_up_klogd);
+ }
+ local_irq_restore(flags);
}
/**
_
Patches currently in -mm which might be from a.p.zijlstra@xxxxxxxxx are
origin.patch
printk-robustify-printk.patch
linux-next.patch
sched-type-fix.patch
lockdep-fix-combinatorial-explosion-in-lock-subgraph-traversal.patch
lockdep-fix-combinatorial-explosion-in-lock-subgraph-traversal-fix.patch
lockdep-lock_set_subclass-reset-a-held-locks-subclass.patch
lockdep-re-annotate-scheduler-runqueues.patch
lockdep-shrink-held_lock-structure.patch
lockdep-shrink-held_lock-structure-fix.patch
lockdep-shrink-held_lock-structure-fix-2.patch
lockdep-map_acquire.patch
lockdep-lock-protection-locks.patch
lockdep-spin_lock_nest_lock.patch
lockdep-spin_lock_nest_lock-fix.patch
lockdep-spin_lock_nest_lock-fix-checkpatch-fixes.patch
lockdep-annotate-mm_take_all_locks.patch
lockdep-handle-chains-involving-classes-defined-in-modules.patch
mm-fix-mm_take_all_locks-locking-order.patch
irq-warn-about-irqf_disabledirqf_shared.patch
--
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