From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail333.us4.mandrillapp.com ([205.201.137.77]:37125 "EHLO mail333.us4.mandrillapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752768AbcCAIQS convert rfc822-to-8bit (ORCPT ); Tue, 1 Mar 2016 03:16:18 -0500 Received: from pmta03.dal05.mailchimp.com (127.0.0.1) by mail333.us4.mandrillapp.com id hql7t4174nod for ; Tue, 1 Mar 2016 08:15:59 +0000 (envelope-from ) From: Subject: Patch "genirq: Prevent chip buslock deadlock" has been added to the 3.10-stable tree To: , , Cc: , Message-Id: <14568163608065@kroah.com> Date: Tue, 01 Mar 2016 08:15:59 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled genirq: Prevent chip buslock deadlock to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: genirq-prevent-chip-buslock-deadlock.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From abc7e40c81d113ef4bacb556f0a77ca63ac81d85 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sun, 13 Dec 2015 18:12:30 +0100 Subject: genirq: Prevent chip buslock deadlock MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Thomas Gleixner commit abc7e40c81d113ef4bacb556f0a77ca63ac81d85 upstream. If a interrupt chip utilizes chip->buslock then free_irq() can deadlock in the following way: CPU0 CPU1 interrupt(X) (Shared or spurious) free_irq(X) interrupt_thread(X) chip_bus_lock(X) irq_finalize_oneshot(X) chip_bus_lock(X) synchronize_irq(X) synchronize_irq() waits for the interrupt thread to complete, i.e. forever. Solution is simple: Drop chip_bus_lock() before calling synchronize_irq() as we do with the irq_desc lock. There is nothing to be protected after the point where irq_desc lock has been released. This adds chip_bus_lock/unlock() to the remove_irq() code path, but that's actually correct in the case where remove_irq() is called on such an interrupt. The current users of remove_irq() are not affected as none of those interrupts is on a chip which requires buslock. Reported-by: Fredrik Markström Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- kernel/irq/manage.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1229,6 +1229,7 @@ static struct irqaction *__free_irq(unsi if (!desc) return NULL; + chip_bus_lock(desc); raw_spin_lock_irqsave(&desc->lock, flags); /* @@ -1242,7 +1243,7 @@ static struct irqaction *__free_irq(unsi if (!action) { WARN(1, "Trying to free already-free IRQ %d\n", irq); raw_spin_unlock_irqrestore(&desc->lock, flags); - + chip_bus_sync_unlock(desc); return NULL; } @@ -1265,6 +1266,7 @@ static struct irqaction *__free_irq(unsi #endif raw_spin_unlock_irqrestore(&desc->lock, flags); + chip_bus_sync_unlock(desc); unregister_handler_proc(irq, action); @@ -1338,9 +1340,7 @@ void free_irq(unsigned int irq, void *de desc->affinity_notify = NULL; #endif - chip_bus_lock(desc); kfree(__free_irq(irq, dev_id)); - chip_bus_sync_unlock(desc); } EXPORT_SYMBOL(free_irq); Patches currently in stable-queue which might be from tglx@linutronix.de are queue-3.10/genirq-prevent-chip-buslock-deadlock.patch