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ide: Handle irq disabling consistently

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sebastian Andrzej Siewior 2018-05-04 16:24:44 +02:00 committed by David S. Miller
parent 820ec411e6
commit 56f0ddadce
1 changed files with 2 additions and 2 deletions
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4
drivers/ide/ide-io.c
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@ -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) {