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Subject[PATCH 3.4 121/134] mmc: mxs-mmc: fix deadlock caused by recursion loop
Date
3.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Lauri Hintsala <lauri.hintsala@bluegiga.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@kinali.ch>
Signed-off-by: Lauri Hintsala <lauri.hintsala@bluegiga.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.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@decadent.org.uk>
Cc: Qiang Huang <h.huangqiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mmc/host/mxs-mmc.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/mmc/host/mxs-mmc.c
+++ b/drivers/mmc/host/mxs-mmc.c
@@ -639,10 +639,6 @@ 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);
@@ -651,6 +647,10 @@ 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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