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omap_hsmmc: prevent races with irq handler

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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>
This commit is contained in:
Adrian Hunter 2009-09-22 16:44:58 -07:00 committed by Linus Torvalds
parent 23050103c2
commit 4dffd7a251
1 changed files with 25 additions and 0 deletions
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25
drivers/mmc/host/omap_hsmmc.c
View file

@ -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)) {