Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757420AbZANTmS (ORCPT ); Wed, 14 Jan 2009 14:42:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754067AbZANTmF (ORCPT ); Wed, 14 Jan 2009 14:42:05 -0500 Received: from rtsoft3.corbina.net ([85.21.88.6]:64087 "EHLO buildserver.ru.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753089AbZANTmE (ORCPT ); Wed, 14 Jan 2009 14:42:04 -0500 Date: Wed, 14 Jan 2009 22:41:59 +0300 From: Anton Vorontsov To: Pierre Ossman Cc: sdhci-devel@list.drzeus.cx, linux-kernel@vger.kernel.org Subject: [PATCH] sdhci: Fix potential spinlock recursion Message-ID: <20090114194159.GA25017@oksana.dev.rtsoft.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2991 Lines: 80 I noticed this bug while working on a driver that is derived from the SDHCI driver: BUG: spinlock recursion on CPU#0, swapper/0 lock: df890668, .magic: dead4ead, .owner: swapper/0, .owner_cpu: 0 Call Trace: [c04b5c50] [c0008b2c] show_stack+0x4c/0x16c (unreliable) [c04b5c90] [c0193aa8] spin_bug+0x7c/0xc4 [c04b5cb0] [c0193dcc] _raw_spin_lock+0xb4/0xb8 [c04b5cc0] [c035baf4] _spin_lock+0x10/0x20 [c04b5cd0] [c02a8d60] esdhc_irq+0x20/0x210 [c04b5cf0] [c00665c0] handle_IRQ_event+0x5c/0xb0 [c04b5d10] [c0068708] handle_level_irq+0xa8/0x144 [c04b5d30] [c000684c] do_IRQ+0xac/0xec [c04b5d50] [c0014f24] ret_from_except+0x0/0x14 --- Exception: 501 at __delay+0x34/0x74 LR = esdhc_reset+0xa4/0x114 [c04b5e10] [c0480000] empty_zero_page+0x0/0x1000 (unreliable) [c04b5e30] [c02a9150] esdhc_tasklet_card+0x104/0x148 [c04b5e50] [c003cabc] tasklet_action+0x78/0xfc [c04b5e60] [c003cbc4] __do_softirq+0x84/0x124 [c04b5e90] [c00065dc] do_softirq+0x58/0x5c [c04b5ea0] [c003ca40] irq_exit+0x94/0x98 [c04b5eb0] [c0006850] do_IRQ+0xb0/0xec [c04b5ed0] [c0014f24] ret_from_except+0x0/0x14 --- Exception: 501 at cpu_idle+0xa0/0xec LR = cpu_idle+0xa0/0xec [c04b5f90] [c0009d14] cpu_idle+0x50/0xec (unreliable) [c04b5fb0] [c035c000] __got2_end+0x58/0x68 [c04b5fc0] [c04468fc] start_kernel+0x1a4/0x228 [c04b5ff0] [00003438] 0x3438 This happens because plain spin_lock() won't protect us from softirqs (tasklets). So in the sdhci interrupt handler we must grab the _irq version of the lock. Note that the _irqsave version isn't mandatory here because a) we aren't trying to protect ourselves from another hardirq, and b) the sdhci driver requests irqs with IRQF_SHARED flag, and that guarantees that we'll get a huge warning if anyone will try to request the same interrupt with IRQF_DISABLED flag, since IRQF_SHARED | IRQF_DISABLED is guaranteed to be broken anyway. Briefly looking into other mmc hosts I don't see any problems with them, so the fix goes for the sdhci driver only. Signed-off-by: Anton Vorontsov --- drivers/mmc/host/sdhci.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 4d010a9..5248041 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -1363,7 +1363,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id) u32 intmask; int cardint = 0; - spin_lock(&host->lock); + spin_lock_irq(&host->lock); intmask = readl(host->ioaddr + SDHCI_INT_STATUS); @@ -1424,7 +1424,7 @@ static irqreturn_t sdhci_irq(int irq, void *dev_id) mmiowb(); out: - spin_unlock(&host->lock); + spin_unlock_irq(&host->lock); /* * We have to delay this as it calls back into the driver. -- 1.5.6.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/