From mboxrd@z Thu Jan 1 00:00:00 1970 From: Doug Anderson Subject: [PATCH 3/3] mmc: dw_mmc: Add locking around cmd11 timer Date: Fri, 3 Apr 2015 11:13:07 -0700 Message-ID: <1428084787-8710-3-git-send-email-dianders@chromium.org> References: <1428084787-8710-1-git-send-email-dianders@chromium.org> Return-path: In-Reply-To: <1428084787-8710-1-git-send-email-dianders@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Jaehoon Chung , Seungwon Jeon , Ulf Hansson Cc: Alim Akhtar , Sonny Rao , Andrew Bresticker , Heiko Stuebner , Addy Ke , Alexandru Stan , javier.martinez@collabora.co.uk, linux-rockchip@lists.infradead.org, Doug Anderson , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-mmc@vger.kernel.org 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 --- drivers/mmc/host/dw_mmc.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 357ef04..105a602 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -1022,14 +1022,23 @@ 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) @@ -2170,11 +2179,20 @@ 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) { -- 2.2.0.rc0.207.ga3a616c