Commit 56f0ddad authored May 04, 2018 by Sebastian Andrzej Siewior Committed by David S. Miller Jun 05, 2018

ide: Handle irq disabling consistently

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>

parent 820ec411

drivers/ide/ide-io.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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) {

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