From 4dffd7a251172d78a157ff45ec1207012f44774a Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Tue, 22 Sep 2009 16:44:58 -0700 Subject: [PATCH] omap_hsmmc: prevent races with irq handler If an unexpected interrupt occurs while preparing the next request, an oops can occur. For example, a new request is setting up DMA for data transfer so host->data is not NULL. An unexpected transfer complete (TC) interrupt comes along and the interrupt handler sets host->data to NULL. Oops! Prevent that by adding a spinlock. Signed-off-by: Adrian Hunter Acked-by: Matt Fleming Cc: Ian Molton Cc: "Roberto A. Foglietta" Cc: Jarkko Lavinen Cc: Denis Karpov Cc: Pierre Ossman Cc: Philip Langdale Cc: "Madhusudhan" Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/mmc/host/omap_hsmmc.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c index f9ed5e23f145..0bfea9c2a597 100644 --- a/drivers/mmc/host/omap_hsmmc.c +++ b/drivers/mmc/host/omap_hsmmc.c @@ -148,6 +148,8 @@ struct mmc_omap_host { struct work_struct mmc_carddetect_work; void __iomem *base; resource_size_t mapbase; + spinlock_t irq_lock; /* Prevent races with irq handler */ + unsigned long flags; unsigned int id; unsigned int dma_len; unsigned int dma_sg_idx; @@ -459,6 +461,14 @@ mmc_omap_start_command(struct mmc_omap_host *host, struct mmc_command *cmd, if (host->use_dma) cmdreg |= DMA_EN; + /* + * In an interrupt context (i.e. STOP command), the spinlock is unlocked + * by the interrupt handler, otherwise (i.e. for a new request) it is + * unlocked here. + */ + if (!in_interrupt()) + spin_unlock_irqrestore(&host->irq_lock, host->flags); + OMAP_HSMMC_WRITE(host->base, ARG, cmd->arg); OMAP_HSMMC_WRITE(host->base, CMD, cmdreg); } @@ -621,11 +631,14 @@ static irqreturn_t mmc_omap_irq(int irq, void *dev_id) struct mmc_data *data; int end_cmd = 0, end_trans = 0, status; + spin_lock(&host->irq_lock); + if (host->mrq == NULL) { OMAP_HSMMC_WRITE(host->base, STAT, OMAP_HSMMC_READ(host->base, STAT)); /* Flush posted write */ OMAP_HSMMC_READ(host->base, STAT); + spin_unlock(&host->irq_lock); return IRQ_HANDLED; } @@ -690,6 +703,8 @@ static irqreturn_t mmc_omap_irq(int irq, void *dev_id) if ((end_trans || (status & TC)) && host->mrq) mmc_omap_xfer_done(host, data); + spin_unlock(&host->irq_lock); + return IRQ_HANDLED; } @@ -1018,6 +1033,13 @@ static void omap_mmc_request(struct mmc_host *mmc, struct mmc_request *req) struct mmc_omap_host *host = mmc_priv(mmc); int err; + /* + * Prevent races with the interrupt handler because of unexpected + * interrupts, but not if we are already in interrupt context i.e. + * retries. + */ + if (!in_interrupt()) + spin_lock_irqsave(&host->irq_lock, host->flags); WARN_ON(host->mrq != NULL); host->mrq = req; err = mmc_omap_prepare_data(host, req); @@ -1026,6 +1048,8 @@ static void omap_mmc_request(struct mmc_host *mmc, struct mmc_request *req) if (req->data) req->data->error = err; host->mrq = NULL; + if (!in_interrupt()) + spin_unlock_irqrestore(&host->irq_lock, host->flags); mmc_request_done(mmc, req); return; } @@ -1580,6 +1604,7 @@ static int __init omap_mmc_probe(struct platform_device *pdev) mmc->f_max = 52000000; sema_init(&host->sem, 1); + spin_lock_init(&host->irq_lock); host->iclk = clk_get(&pdev->dev, "ick"); if (IS_ERR(host->iclk)) { -- 2.20.1