From c685689fd24d310343ac33942e9a54a974ae9c43 Mon Sep 17 00:00:00 2001 From: Chuansheng Liu Date: Mon, 24 Feb 2014 11:29:50 +0800 Subject: [PATCH 1/2] genirq: Remove racy waitqueue_active check We hit one rare case below: T1 calling disable_irq(), but hanging at synchronize_irq() always; The corresponding irq thread is in sleeping state; And all CPUs are in idle state; After analysis, we found there is one possible scenerio which causes T1 is waiting there forever: CPU0 CPU1 synchronize_irq() wait_event() spin_lock() atomic_dec_and_test(&threads_active) insert the __wait into queue spin_unlock() if(waitqueue_active) atomic_read(&threads_active) wake_up() Here after inserted the __wait into queue on CPU0, and before test if queue is empty on CPU1, there is no barrier, it maybe cause it is not visible for CPU1 immediately, although CPU0 has updated the queue list. It is similar for CPU0 atomic_read() threads_active also. So we'd need one smp_mb() before waitqueue_active.that, but removing the waitqueue_active() check solves it as wel l and it makes things simple and clear. Signed-off-by: Chuansheng Liu Cc: Xiaoming Wang Link: http://lkml.kernel.org/r/1393212590-32543-1-git-send-email-chuansheng.liu@intel.com Cc: stable@vger.kernel.org Signed-off-by: Thomas Gleixner --- kernel/irq/manage.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 481a13c43b17..d3bf660cb57f 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -802,8 +802,7 @@ static irqreturn_t irq_thread_fn(struct irq_desc *desc, static void wake_threads_waitq(struct irq_desc *desc) { - if (atomic_dec_and_test(&desc->threads_active) && - waitqueue_active(&desc->wait_for_threads)) + if (atomic_dec_and_test(&desc->threads_active)) wake_up(&desc->wait_for_threads); } From 64be38ab03e9b238a1299857fef8b3707c0ed045 Mon Sep 17 00:00:00 2001 From: Rashika Kheria Date: Thu, 27 Feb 2014 17:10:12 +0530 Subject: [PATCH 2/2] genirq: Include missing header file in irqdomain.c MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Include appropriate header file include/linux/of_irq.h in kernel/irq/irqdomain.c because it contains prototype definition of function define in kernel/irq/irqdomain.c. This eliminates the following warning in kernel/irq/irqdomain.c: kernel/irq/irqdomain.c:468:14: warning: no previous prototype for ‘irq_create_of_mapping’ [-Wmissing-prototypes] Signed-off-by: Rashika Kheria Reviewed-by: Josh Triplett Cc: Benjamin Herrenschmidt Link: http://lkml.kernel.org/r/eb89aebea7ff1a46122918ac389ebecf8248be9a.1393493276.git.rashika.kheria@gmail.com Signed-off-by: Thomas Gleixner --- kernel/irq/irqdomain.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index cf68bb36fe58..f14033700c25 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include