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 <adrian.hunter@nokia.com> Acked-by: Matt Fleming <matt@console-pimps.org> Cc: Ian Molton <ian@mnementh.co.uk> Cc: "Roberto A. Foglietta" <roberto.foglietta@gmail.com> Cc: Jarkko Lavinen <jarkko.lavinen@nokia.com> Cc: Denis Karpov <ext-denis.2.karpov@nokia.com> Cc: Pierre Ossman <pierre@ossman.eu> Cc: Philip Langdale <philipl@overt.org> Cc: "Madhusudhan" <madhu.cr@ti.com> Cc: <linux-mmc@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 changed files with 25 additions and 0 deletions
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@ -148,6 +148,8 @@ struct mmc_omap_host {
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struct work_struct mmc_carddetect_work;
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void __iomem *base;
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resource_size_t mapbase;
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spinlock_t irq_lock; /* Prevent races with irq handler */
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unsigned long flags;
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unsigned int id;
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unsigned int dma_len;
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unsigned int dma_sg_idx;
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@ -459,6 +461,14 @@ mmc_omap_start_command(struct mmc_omap_host *host, struct mmc_command *cmd,
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if (host->use_dma)
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cmdreg |= DMA_EN;
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/*
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* In an interrupt context (i.e. STOP command), the spinlock is unlocked
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* by the interrupt handler, otherwise (i.e. for a new request) it is
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* unlocked here.
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*/
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if (!in_interrupt())
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spin_unlock_irqrestore(&host->irq_lock, host->flags);
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OMAP_HSMMC_WRITE(host->base, ARG, cmd->arg);
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OMAP_HSMMC_WRITE(host->base, CMD, cmdreg);
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}
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@ -621,11 +631,14 @@ static irqreturn_t mmc_omap_irq(int irq, void *dev_id)
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struct mmc_data *data;
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int end_cmd = 0, end_trans = 0, status;
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spin_lock(&host->irq_lock);
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if (host->mrq == NULL) {
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OMAP_HSMMC_WRITE(host->base, STAT,
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OMAP_HSMMC_READ(host->base, STAT));
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/* Flush posted write */
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OMAP_HSMMC_READ(host->base, STAT);
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spin_unlock(&host->irq_lock);
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return IRQ_HANDLED;
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}
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@ -690,6 +703,8 @@ static irqreturn_t mmc_omap_irq(int irq, void *dev_id)
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if ((end_trans || (status & TC)) && host->mrq)
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mmc_omap_xfer_done(host, data);
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spin_unlock(&host->irq_lock);
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return IRQ_HANDLED;
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}
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@ -1018,6 +1033,13 @@ static void omap_mmc_request(struct mmc_host *mmc, struct mmc_request *req)
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struct mmc_omap_host *host = mmc_priv(mmc);
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int err;
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/*
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* Prevent races with the interrupt handler because of unexpected
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* interrupts, but not if we are already in interrupt context i.e.
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* retries.
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*/
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if (!in_interrupt())
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spin_lock_irqsave(&host->irq_lock, host->flags);
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WARN_ON(host->mrq != NULL);
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host->mrq = req;
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err = mmc_omap_prepare_data(host, req);
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@ -1026,6 +1048,8 @@ static void omap_mmc_request(struct mmc_host *mmc, struct mmc_request *req)
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if (req->data)
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req->data->error = err;
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host->mrq = NULL;
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if (!in_interrupt())
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spin_unlock_irqrestore(&host->irq_lock, host->flags);
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mmc_request_done(mmc, req);
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return;
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}
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@ -1580,6 +1604,7 @@ static int __init omap_mmc_probe(struct platform_device *pdev)
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mmc->f_max = 52000000;
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sema_init(&host->sem, 1);
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spin_lock_init(&host->irq_lock);
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host->iclk = clk_get(&pdev->dev, "ick");
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if (IS_ERR(host->iclk)) {
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