one more .25 patch

diff --git a/queue-2.6.25/hrtimer-raise-softirq-unlocked-to-avoid-circular-lock-dependency.patch b/queue-2.6.25/hrtimer-raise-softirq-unlocked-to-avoid-circular-lock-dependency.patch
new file mode 100644 (file)
index 0000000..d9a2ef7
--- /dev/null
+++ b/queue-2.6.25/hrtimer-raise-softirq-unlocked-to-avoid-circular-lock-dependency.patch
@@ -0,0 +1,102 @@
+From jejb@kernel.org  Tue Apr 29 09:51:24 2008
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Tue, 29 Apr 2008 01:15:10 GMT
+Subject: hrtimer: raise softirq unlocked to avoid circular lock dependency
+To: jejb@kernel.org, stable@kernel.org
+Message-ID: <200804290115.m3T1FAaX028758@hera.kernel.org>
+
+From: Thomas Gleixner <tglx@linutronix.de>
+
+commit 0c96c5979a522c3323c30a078a70120e29b5bdbc upstream
+
+The scheduler hrtimer bits in 2.6.25 introduced a circular lock
+dependency in a rare code path:
+
+=======================================================
+[ INFO: possible circular locking dependency detected ]
+2.6.25-sched-devel.git-x86-latest.git #19
+-------------------------------------------------------
+X/2980 is trying to acquire lock:
+ (&rq->rq_lock_key#2){++..}, at: [<ffffffff80230146>] task_rq_lock+0x56/0xa0
+
+but task is already holding lock:
+ (&cpu_base->lock){++..}, at: [<ffffffff80257ae1>] lock_hrtimer_base+0x31/0x60
+
+which lock already depends on the new lock.
+
+The scenario which leads to this is:
+
+posix-timer signal is delivered
+ -> posix-timer is rearmed
+    timer is already expired in hrtimer_enqueue()
+     -> softirq is raised
+
+To prevent this we need to move the raise of the softirq out of the
+base->lock protected code path.
+
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
+
+---
+ kernel/hrtimer.c |   19 +++++++++++++++++--
+ 1 file changed, 17 insertions(+), 2 deletions(-)
+
+--- a/kernel/hrtimer.c
++++ b/kernel/hrtimer.c
+@@ -590,7 +590,6 @@ static inline int hrtimer_enqueue_reprog
+                       list_add_tail(&timer->cb_entry,
+                                     &base->cpu_base->cb_pending);
+                       timer->state = HRTIMER_STATE_PENDING;
+-                      raise_softirq(HRTIMER_SOFTIRQ);
+                       return 1;
+               default:
+                       BUG();
+@@ -633,6 +632,11 @@ static int hrtimer_switch_to_hres(void)
+       return 1;
+ }
+ 
++static inline void hrtimer_raise_softirq(void)
++{
++      raise_softirq(HRTIMER_SOFTIRQ);
++}
++
+ #else
+ 
+ static inline int hrtimer_hres_active(void) { return 0; }
+@@ -651,6 +655,7 @@ static inline int hrtimer_reprogram(stru
+ {
+       return 0;
+ }
++static inline void hrtimer_raise_softirq(void) { }
+ 
+ #endif /* CONFIG_HIGH_RES_TIMERS */
+ 
+@@ -850,7 +855,7 @@ hrtimer_start(struct hrtimer *timer, kti
+ {
+       struct hrtimer_clock_base *base, *new_base;
+       unsigned long flags;
+-      int ret;
++      int ret, raise;
+ 
+       base = lock_hrtimer_base(timer, &flags);
+ 
+@@ -884,8 +889,18 @@ hrtimer_start(struct hrtimer *timer, kti
+       enqueue_hrtimer(timer, new_base,
+                       new_base->cpu_base == &__get_cpu_var(hrtimer_bases));
+ 
++      /*
++       * The timer may be expired and moved to the cb_pending
++       * list. We can not raise the softirq with base lock held due
++       * to a possible deadlock with runqueue lock.
++       */
++      raise = timer->state == HRTIMER_STATE_PENDING;
++
+       unlock_hrtimer_base(timer, &flags);
+ 
++      if (raise)
++              hrtimer_raise_softirq();
++
+       return ret;
+ }
+ EXPORT_SYMBOL_GPL(hrtimer_start);

diff --git a/queue-2.6.25/series b/queue-2.6.25/series
index 770b7b3af64a9c84d2e67e1116480de8a9a56a8e..ab1d7c78e1925707aa6d5f8c04bae47daddc952e 100644 (file)
--- a/queue-2.6.25/series
+++ b/queue-2.6.25/series
@@ -34,3 +34,4 @@ rdma-nes-fix-adapter-reset-after-pxe-boot.patch
 scsi-qla2xxx-correct-regression-in-relogin-code.patch
 alpha-unbreak-osf-1-binaries.patch
 x86-fix-32-bit-x86-msi-x-allocation-leakage.patch
+hrtimer-raise-softirq-unlocked-to-avoid-circular-lock-dependency.patch