linux-kernel - [ 033/135] mmc: mxs-mmc: fix deadlock caused by recursion loop

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Date:	Mon, 17 Sep 2012 01:36:58 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk,
	Lauri Hintsala <lauri.hintsala@...egiga.com>,
	Attila Kinali <attila@...ali.ch>,
	Shawn Guo <shawn.guo@...aro.org>, Chris Ball <cjb@...top.org>
Subject: [ 033/135] mmc: mxs-mmc: fix deadlock caused by recursion loop

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lauri Hintsala <lauri.hintsala@...egiga.com>

commit fc108d24d3a6da63576a460e122fa1df0cbdea20 upstream.

Release the lock before mmc_signal_sdio_irq is called by
mxs_mmc_enable_sdio_irq.

Backtrace:
[   65.470000] =============================================
[   65.470000] [ INFO: possible recursive locking detected ]
[   65.470000] 3.5.0-rc5 #2 Not tainted
[   65.470000] ---------------------------------------------
[   65.470000] ksdioirqd/mmc0/73 is trying to acquire lock:
[   65.470000]  (&(&host->lock)->rlock#2){-.-...}, at: [<bf054120>] mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]
[   65.470000]
[   65.470000] but task is already holding lock:
[   65.470000]  (&(&host->lock)->rlock#2){-.-...}, at: [<bf054120>] mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]
[   65.470000]
[   65.470000] other info that might help us debug this:
[   65.470000]  Possible unsafe locking scenario:
[   65.470000]
[   65.470000]        CPU0
[   65.470000]        ----
[   65.470000]   lock(&(&host->lock)->rlock#2);
[   65.470000]   lock(&(&host->lock)->rlock#2);
[   65.470000]
[   65.470000]  *** DEADLOCK ***
[   65.470000]
[   65.470000]  May be due to missing lock nesting notation
[   65.470000]
[   65.470000] 1 lock held by ksdioirqd/mmc0/73:
[   65.470000]  #0:  (&(&host->lock)->rlock#2){-.-...}, at: [<bf054120>] mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]
[   65.470000]
[   65.470000] stack backtrace:
[   65.470000] [<c0014990>] (unwind_backtrace+0x0/0xf4) from [<c005ccb8>] (__lock_acquire+0x14f8/0x1b98)
[   65.470000] [<c005ccb8>] (__lock_acquire+0x14f8/0x1b98) from [<c005d3f8>] (lock_acquire+0xa0/0x108)
[   65.470000] [<c005d3f8>] (lock_acquire+0xa0/0x108) from [<c02f671c>] (_raw_spin_lock_irqsave+0x48/0x5c)
[   65.470000] [<c02f671c>] (_raw_spin_lock_irqsave+0x48/0x5c) from [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc])
[   65.470000] [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]) from [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc])
[   65.470000] [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc]) from [<c0219b38>] (sdio_irq_thread+0x1bc/0x274)
[   65.470000] [<c0219b38>] (sdio_irq_thread+0x1bc/0x274) from [<c003c324>] (kthread+0x8c/0x98)
[   65.470000] [<c003c324>] (kthread+0x8c/0x98) from [<c00101ac>] (kernel_thread_exit+0x0/0x8)
[   65.470000] BUG: spinlock lockup suspected on CPU#0, ksdioirqd/mmc0/73
[   65.470000]  lock: 0xc3358724, .magic: dead4ead, .owner: ksdioirqd/mmc0/73, .owner_cpu: 0
[   65.470000] [<c0014990>] (unwind_backtrace+0x0/0xf4) from [<c01b46b0>] (do_raw_spin_lock+0x100/0x144)
[   65.470000] [<c01b46b0>] (do_raw_spin_lock+0x100/0x144) from [<c02f6724>] (_raw_spin_lock_irqsave+0x50/0x5c)
[   65.470000] [<c02f6724>] (_raw_spin_lock_irqsave+0x50/0x5c) from [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc])
[   65.470000] [<bf054120>] (mxs_mmc_enable_sdio_irq+0x18/0xdc [mxs_mmc]) from [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc])
[   65.470000] [<bf0541d0>] (mxs_mmc_enable_sdio_irq+0xc8/0xdc [mxs_mmc]) from [<c0219b38>] (sdio_irq_thread+0x1bc/0x274)
[   65.470000] [<c0219b38>] (sdio_irq_thread+0x1bc/0x274) from [<c003c324>] (kthread+0x8c/0x98)
[   65.470000] [<c003c324>] (kthread+0x8c/0x98) from [<c00101ac>] (kernel_thread_exit+0x0/0x8)

Reported-by: Attila Kinali <attila@...ali.ch>
Signed-off-by: Lauri Hintsala <lauri.hintsala@...egiga.com>
Acked-by: Shawn Guo <shawn.guo@...aro.org>
Signed-off-by: Chris Ball <cjb@...top.org>
[bwh: Backported to 3.2:
 - Adjust context
 - HW_SSP_STATUS is a simple rather than function-like macro]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/mmc/host/mxs-mmc.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/drivers/mmc/host/mxs-mmc.c
+++ b/drivers/mmc/host/mxs-mmc.c
@@ -628,10 +628,6 @@ static void mxs_mmc_enable_sdio_irq(stru
 		       host->base + HW_SSP_CTRL0 + MXS_SET_ADDR);
 		writel(BM_SSP_CTRL1_SDIO_IRQ_EN,
 		       host->base + HW_SSP_CTRL1 + MXS_SET_ADDR);
-
-		if (readl(host->base + HW_SSP_STATUS) & BM_SSP_STATUS_SDIO_IRQ)
-			mmc_signal_sdio_irq(host->mmc);
-
 	} else {
 		writel(BM_SSP_CTRL0_SDIO_IRQ_CHECK,
 		       host->base + HW_SSP_CTRL0 + MXS_CLR_ADDR);
@@ -640,6 +636,10 @@ static void mxs_mmc_enable_sdio_irq(stru
 	}
 
 	spin_unlock_irqrestore(&host->lock, flags);
+
+	if (enable && readl(host->base + HW_SSP_STATUS) & BM_SSP_STATUS_SDIO_IRQ)
+		mmc_signal_sdio_irq(host->mmc);
+
 }
 
 static const struct mmc_host_ops mxs_mmc_ops = {


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