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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>
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parent
077797117d
commit
34cb275283
1 changed files with 13 additions and 5 deletions
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@ -37,6 +37,11 @@ struct uio_pdrv_genirq_platdata {
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struct platform_device *pdev;
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struct platform_device *pdev;
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};
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};
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/* Bits in uio_pdrv_genirq_platdata.flags */
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enum {
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UIO_IRQ_DISABLED = 0,
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};
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static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
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static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
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{
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{
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struct uio_pdrv_genirq_platdata *priv = info->priv;
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struct uio_pdrv_genirq_platdata *priv = info->priv;
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@ -63,8 +68,10 @@ static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
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* remember the state so we can allow user space to enable it later.
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* remember the state so we can allow user space to enable it later.
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*/
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*/
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if (!test_and_set_bit(0, &priv->flags))
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spin_lock(&priv->lock);
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if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
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disable_irq_nosync(irq);
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disable_irq_nosync(irq);
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spin_unlock(&priv->lock);
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return IRQ_HANDLED;
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return IRQ_HANDLED;
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}
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}
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@ -78,16 +85,17 @@ static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
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* in the interrupt controller, but keep track of the
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* in the interrupt controller, but keep track of the
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* state to prevent per-irq depth damage.
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* state to prevent per-irq depth damage.
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*
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*
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* Serialize this operation to support multiple tasks.
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* Serialize this operation to support multiple tasks and concurrency
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* with irq handler on SMP systems.
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*/
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*/
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spin_lock_irqsave(&priv->lock, flags);
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spin_lock_irqsave(&priv->lock, flags);
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if (irq_on) {
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if (irq_on) {
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if (test_and_clear_bit(0, &priv->flags))
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if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
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enable_irq(dev_info->irq);
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enable_irq(dev_info->irq);
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} else {
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} else {
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if (!test_and_set_bit(0, &priv->flags))
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if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
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disable_irq(dev_info->irq);
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disable_irq_nosync(dev_info->irq);
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}
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}
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spin_unlock_irqrestore(&priv->lock, flags);
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spin_unlock_irqrestore(&priv->lock, flags);
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