diff options
| author | Vitalii Demianets <vitas@nppfactor.kiev.ua> | 2013-06-20 16:36:00 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-06-24 16:31:21 -0700 |
| commit | 34cb27528398738bea94852b99ef8fb05944ec41 (patch) | |
| tree | 88a9e99282138bd21af563b98ab65ccc8ab088be /drivers/uio | |
| parent | 077797117dfa209717e1f3f1416c1101c0e047f0 (diff) | |
UIO: Fix concurrency issue
In a SMP case there was a race condition issue between
uio_pdrv_genirq_irqcontrol() running on one CPU and irq handler on
another CPU. Fix it by spin_locking shared resources access inside irq
handler. Also:
- Change disable_irq to disable_irq_nosync to avoid deadlock, because
disable_irq waits for the completion of the irq handler;
- Change atomic bit-manipulation routines to their non-atomic
counterparts as we already are guarding the code by spinlock.
Signed-off-by: Vitalii Demianets <vitas@nppfactor.kiev.ua>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/uio')
| -rw-r--r-- | drivers/uio/uio_pdrv_genirq.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/drivers/uio/uio_pdrv_genirq.c b/drivers/uio/uio_pdrv_genirq.c index 97415492779e..bcd72f3a62c3 100644 --- a/drivers/uio/uio_pdrv_genirq.c +++ b/drivers/uio/uio_pdrv_genirq.c @@ -37,6 +37,11 @@ struct uio_pdrv_genirq_platdata { struct platform_device *pdev; }; +/* Bits in uio_pdrv_genirq_platdata.flags */ +enum { + UIO_IRQ_DISABLED = 0, +}; + static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode) { struct uio_pdrv_genirq_platdata *priv = info->priv; @@ -63,8 +68,10 @@ static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info) * remember the state so we can allow user space to enable it later. */ - if (!test_and_set_bit(0, &priv->flags)) + spin_lock(&priv->lock); + if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) disable_irq_nosync(irq); + spin_unlock(&priv->lock); return IRQ_HANDLED; } @@ -78,16 +85,17 @@ static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on) * in the interrupt controller, but keep track of the * state to prevent per-irq depth damage. * - * Serialize this operation to support multiple tasks. + * Serialize this operation to support multiple tasks and concurrency + * with irq handler on SMP systems. */ spin_lock_irqsave(&priv->lock, flags); if (irq_on) { - if (test_and_clear_bit(0, &priv->flags)) + if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags)) enable_irq(dev_info->irq); } else { - if (!test_and_set_bit(0, &priv->flags)) - disable_irq(dev_info->irq); + if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) + disable_irq_nosync(dev_info->irq); } spin_unlock_irqrestore(&priv->lock, flags); |