Hi On Wed, 11 May 2011, Dong, Chuanxiao wrote: > Hello Liakhovetski, > > Right now I am facing some problem during kernel booting which indicate > caused by MMC driver. So I think I encountered the race condition you > mentioned below. Which kernel are you using? With my patch or without it? What makes you think, that your problem is caused by a race in MMC? Races rarely occur reproducibly, so, it seems a bit unlikely to me during the boot process. > I have gone through MMC stack code, seems sdhci_set_ios already wrapped > by spin lock/unlock, so I am a little not understanding why there is > still a race condition? Again, are you referring to the kernel before my patch or after? Thanks Guennadi > Is this race condition caused by sdhci_set_ios function reenter or > something else? > > Thanks for your help on this. > > BR > Chuanxiao > -----Original Message----- > From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc-owner@xxxxxxxxxxxxxxx] On Behalf Of Guennadi Liakhovetski > Sent: Saturday, April 16, 2011 2:08 AM > To: linux-sh@xxxxxxxxxxxxxxx > Cc: linux-mmc@xxxxxxxxxxxxxxx; Magnus Damm; Simon Horman; Linus Walleij > Subject: [PATCH] MMC: fix a race between card-detect rescan and clock-gate work instances > > Currently there is a race in the MMC core between a card-detect > rescan work and the clock-gating work, scheduled from a command > completion. Fix it by removing the dedicated clock-gating mutex and > using the MMC standard locking mechanism instead. > > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx> > Cc: Simon Horman <horms@xxxxxxxxxxxx> > Cc: Magnus Damm <damm@xxxxxxxxxxxxx> > Cc: Linus Walleij <linus.walleij@xxxxxxxxxx> > --- > drivers/mmc/core/host.c | 9 ++++----- > include/linux/mmc/host.h | 1 - > 2 files changed, 4 insertions(+), 6 deletions(-) > > diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c > index 461e6a1..2b200c1 100644 > --- a/drivers/mmc/core/host.c > +++ b/drivers/mmc/core/host.c > @@ -94,7 +94,7 @@ static void mmc_host_clk_gate_delayed(struct mmc_host *host) > spin_unlock_irqrestore(&host->clk_lock, flags); > return; > } > - mutex_lock(&host->clk_gate_mutex); > + mmc_claim_host(host); > spin_lock_irqsave(&host->clk_lock, flags); > if (!host->clk_requests) { > spin_unlock_irqrestore(&host->clk_lock, flags); > @@ -104,7 +104,7 @@ static void mmc_host_clk_gate_delayed(struct mmc_host *host) > pr_debug("%s: gated MCI clock\n", mmc_hostname(host)); > } > spin_unlock_irqrestore(&host->clk_lock, flags); > - mutex_unlock(&host->clk_gate_mutex); > + mmc_release_host(host); > } > > /* > @@ -130,7 +130,7 @@ void mmc_host_clk_ungate(struct mmc_host *host) > { > unsigned long flags; > > - mutex_lock(&host->clk_gate_mutex); > + mmc_claim_host(host); > spin_lock_irqsave(&host->clk_lock, flags); > if (host->clk_gated) { > spin_unlock_irqrestore(&host->clk_lock, flags); > @@ -140,7 +140,7 @@ void mmc_host_clk_ungate(struct mmc_host *host) > } > host->clk_requests++; > spin_unlock_irqrestore(&host->clk_lock, flags); > - mutex_unlock(&host->clk_gate_mutex); > + mmc_release_host(host); > } > > /** > @@ -215,7 +215,6 @@ static inline void mmc_host_clk_init(struct mmc_host *host) > host->clk_gated = false; > INIT_WORK(&host->clk_gate_work, mmc_host_clk_gate_work); > spin_lock_init(&host->clk_lock); > - mutex_init(&host->clk_gate_mutex); > } > > /** > diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h > index bcb793e..eb792cb 100644 > --- a/include/linux/mmc/host.h > +++ b/include/linux/mmc/host.h > @@ -183,7 +183,6 @@ struct mmc_host { > struct work_struct clk_gate_work; /* delayed clock gate */ > unsigned int clk_old; /* old clock value cache */ > spinlock_t clk_lock; /* lock for clk fields */ > - struct mutex clk_gate_mutex; /* mutex for clock gating */ > #endif > > /* host specific block data */ > -- > 1.7.2.5 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
