From: Doug Anderson Date: Fri, 3 Apr 2015 18:13:07 +0000 (-0700) Subject: mmc: dw_mmc: Add locking around cmd11 timer X-Git-Tag: firefly_0821_release~176^2~2011^2~8 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=49ba030221d23ad8e35deb66b74873b852f4d7bf;p=firefly-linux-kernel-4.4.55.git mmc: dw_mmc: Add locking around cmd11 timer It is possible for the cmd11 interrupt to fire and delete the cmd11_timer before the cmd11_timer was actually setup. Let's fix this race by adding a few spinlocks. Note that the race wasn't seen in practice without adding some printk statements, but it still seems wise to fix. Fixes: 5c935165da79 ("mmc: dw_mmc: Add a timeout for sending CMD11") Signed-off-by: Doug Anderson Signed-off-by: Jaehoon Chung Signed-off-by: Ulf Hansson --- diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index c2b568352ce3..38b29265cc7c 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1023,14 +1023,23 @@ static void __dw_mci_start_request(struct dw_mci *host, dw_mci_start_command(host, cmd, cmdflags); if (cmd->opcode == SD_SWITCH_VOLTAGE) { + unsigned long irqflags; + /* * Databook says to fail after 2ms w/ no response, but evidence * shows that sometimes the cmd11 interrupt takes over 130ms. * We'll set to 500ms, plus an extra jiffy just in case jiffies * is just about to roll over. + * + * We do this whole thing under spinlock and only if the + * command hasn't already completed (indicating the the irq + * already ran so we don't want the timeout). */ - mod_timer(&host->cmd11_timer, - jiffies + msecs_to_jiffies(500) + 1); + spin_lock_irqsave(&host->irq_lock, irqflags); + if (!test_bit(EVENT_CMD_COMPLETE, &host->pending_events)) + mod_timer(&host->cmd11_timer, + jiffies + msecs_to_jiffies(500) + 1); + spin_unlock_irqrestore(&host->irq_lock, irqflags); } if (mrq->stop) @@ -2160,11 +2169,20 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id) /* Check volt switch first, since it can look like an error */ if ((host->state == STATE_SENDING_CMD11) && (pending & SDMMC_INT_VOLT_SWITCH)) { - del_timer(&host->cmd11_timer); + unsigned long irqflags; mci_writel(host, RINTSTS, SDMMC_INT_VOLT_SWITCH); pending &= ~SDMMC_INT_VOLT_SWITCH; + + /* + * Hold the lock; we know cmd11_timer can't be kicked + * off after the lock is released, so safe to delete. + */ + spin_lock_irqsave(&host->irq_lock, irqflags); dw_mci_cmd_interrupt(host, pending); + spin_unlock_irqrestore(&host->irq_lock, irqflags); + + del_timer(&host->cmd11_timer); } if (pending & DW_MCI_CMD_ERROR_FLAGS) {