mmc: mxs: DEADLOCK

[Attila Kinali]

On Wed, 11 Jul 2012 14:06:09 +0800
Shawn Guo <shawn.guo at linaro.org> wrote:


> > I found a way to fix this issue:
> > 
> > --- a/drivers/mmc/host/mxs-mmc.c
> > +++ b/drivers/mmc/host/mxs-mmc.c
> > @@ -278,11 +278,11 @@ static irqreturn_t mxs_mmc_irq_handler(int
> > irq, void *dev_id)
> >  	writel(stat & MXS_MMC_IRQ_BITS,
> >  	       host->base + HW_SSP_CTRL1(host) + STMP_OFFSET_REG_CLR);
> > 
> > +	spin_unlock(&host->lock);
> > +
> >  	if ((stat & BM_SSP_CTRL1_SDIO_IRQ) && (stat & BM_SSP_CTRL1_SDIO_IRQ_EN))
> >  		mmc_signal_sdio_irq(host->mmc);
> > 
> > -	spin_unlock(&host->lock);
> > -
> >  	if (stat & BM_SSP_CTRL1_RESP_TIMEOUT_IRQ)
> >  		cmd->error = -ETIMEDOUT;
> >  	else if (stat & BM_SSP_CTRL1_RESP_ERR_IRQ)
> > 
> > 
> > Is there any reason to keep mmc_signal_sdio_irq inside the spinlock?
> > mmc_signal_sdio_irq calls mxs_mmc_enable_sdio_irq and it tries to
> > acquire lock while it is already acquired.
> > 
> The fix looks right to me.  You can have my ack when you send a patch
> for it.
> 
> Acked-by: Shawn Guo <shawn.guo at linaro.org>

I ran into the same problem today, but the proposed fix doesn't seem
to work for me:

---schnipp---
# modprobe libertas_sdio
[   59.200000] lib80211: common routines for IEEE802.11 drivers
[   59.240000] cfg80211: Calling CRDA to update world regulatory domain
[   59.320000] libertas_sdio: Libertas SDIO driver
[   59.330000] libertas_sdio: Copyright Pierre Ossman
# modprobe mxs-mmc
[   64.210000] mxs-mmc 80010000.ssp: initialized
[   64.260000] mxs-mmc 80034000.ssp: initialized
[   64.270000] mmc0: new SDIO card at address 0001
# [   65.440000] libertas_sdio mmc0:0001:1: (unregistered net_device): 00:13:04:80:00:3f, fw 9.70.3p24, cap 0x00000303
[   65.470000] 
[   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)
---schnapp---

Any hints how to work around or fix this, would be appreciated

			Attila Kinali

-- 
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the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson