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 <bige...@linutronix.de>
---
drivers/ide/ide-io.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
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) {
--
2.17.0
