Message ID | 20180504142446.30525-3-bigeasy@linutronix.de |
---|---|
State | Accepted |
Delegated to: | David Miller |
Headers | show |
Series | avoid disabling interrupts where it is not required | expand |
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Fri, 4 May 2018 16:24:44 +0200 > ide_timer_expiry() disables interrupt at function entry when acquiring > hwif->lock. Before disabling the device interrupt it unlocks hwif->lock, > but interrupts stay disabled. After the call to disable_irq() interrupts > are disabled again, which is a pointless exercise. > > After the device irq handler has been invoked with interrupts disabled, > hwif->lock is acquired again with spin_lock_irq() because the device irq > handler might have reenabled interrupts. This is not documented and > confusing for the casual reader. > > Remove the redundant local_irq_disable() and add a comment which explains > why hwif->lock has to be reacquired with spin_lock_irq(). > > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: David S. Miller <davem@davemloft.net> -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c index 6f25da56a169..a444bad7a2aa 100644 --- a/drivers/ide/ide-io.c +++ b/drivers/ide/ide-io.c @@ -659,8 +659,7 @@ void ide_timer_expiry (struct timer_list *t) spin_unlock(&hwif->lock); /* disable_irq_nosync ?? */ disable_irq(hwif->irq); - /* local CPU only, as if we were handling an interrupt */ - local_irq_disable(); + if (hwif->polling) { startstop = handler(drive); } else if (drive_is_ready(drive)) { @@ -679,6 +678,7 @@ void ide_timer_expiry (struct timer_list *t) startstop = ide_error(drive, "irq timeout", hwif->tp_ops->read_status(hwif)); } + /* Disable interrupts again, `handler' might have enabled it */ spin_lock_irq(&hwif->lock); enable_irq(hwif->irq); if (startstop == ide_stopped && hwif->polling == 0) {
ide_timer_expiry() disables interrupt at function entry when acquiring hwif->lock. Before disabling the device interrupt it unlocks hwif->lock, but interrupts stay disabled. After the call to disable_irq() interrupts are disabled again, which is a pointless exercise. After the device irq handler has been invoked with interrupts disabled, hwif->lock is acquired again with spin_lock_irq() because the device irq handler might have reenabled interrupts. This is not documented and confusing for the casual reader. Remove the redundant local_irq_disable() and add a comment which explains why hwif->lock has to be reacquired with spin_lock_irq(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/ide/ide-io.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)