Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759558AbcCDJie (ORCPT ); Fri, 4 Mar 2016 04:38:34 -0500 Received: from mx2.suse.de ([195.135.220.15]:59933 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758949AbcCDJDK (ORCPT ); Fri, 4 Mar 2016 04:03:10 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Jiri Slaby Subject: [PATCH 3.12 045/116] genirq: Prevent chip buslock deadlock Date: Fri, 4 Mar 2016 10:01:30 +0100 Message-Id: <5df68eedfb0e3cfa8c23c8b0b28bf032881313e4.1457082108.git.jslaby@suse.cz> X-Mailer: git-send-email 2.7.2 In-Reply-To: References: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2342 Lines: 79 From: Thomas Gleixner 3.12-stable review patch. If anyone has any objections, please let me know. =============== 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: Jiri Slaby --- kernel/irq/manage.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index 75a976a8ed58..504bb4b0d226 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1230,6 +1230,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) if (!desc) return NULL; + chip_bus_lock(desc); raw_spin_lock_irqsave(&desc->lock, flags); /* @@ -1243,7 +1244,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) 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; } @@ -1266,6 +1267,7 @@ static struct irqaction *__free_irq(unsigned int irq, void *dev_id) #endif raw_spin_unlock_irqrestore(&desc->lock, flags); + chip_bus_sync_unlock(desc); unregister_handler_proc(irq, action); @@ -1339,9 +1341,7 @@ void free_irq(unsigned int irq, void *dev_id) desc->affinity_notify = NULL; #endif - chip_bus_lock(desc); kfree(__free_irq(irq, dev_id)); - chip_bus_sync_unlock(desc); } EXPORT_SYMBOL(free_irq); -- 2.7.2