linux-kernel - [PATCH 4/4] ide: don't enable/disable interrupts in force threaded-IRQ mode

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Date:   Fri,  4 May 2018 16:24:46 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     linux-ide@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        "David S. Miller" <davem@...emloft.net>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 4/4] ide: don't enable/disable interrupts in force threaded-IRQ mode

The interrupts are enabled/disabled so the interrupt handler can run
with enabled interrupts while serving the interrupt and not lose other
interrupts especially the timer tick.
If the system runs with force-threaded interrupts then there is no need
to enable the interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 drivers/ide/ide-iops.c     | 13 +++++++++----
 drivers/ide/ide-taskfile.c |  2 +-
 kernel/irq/manage.c        |  1 +
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/ide/ide-iops.c b/drivers/ide/ide-iops.c
index 210a0887dd29..d55e9ebd5628 100644
--- a/drivers/ide/ide-iops.c
+++ b/drivers/ide/ide-iops.c
@@ -108,6 +108,7 @@ int __ide_wait_stat(ide_drive_t *drive, u8 good, u8 bad,
 	ide_hwif_t *hwif = drive->hwif;
 	const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 	unsigned long flags;
+	bool irqs_threaded = force_irqthreads;
 	int i;
 	u8 stat;
 
@@ -115,8 +116,10 @@ int __ide_wait_stat(ide_drive_t *drive, u8 good, u8 bad,
 	stat = tp_ops->read_status(hwif);
 
 	if (stat & ATA_BUSY) {
-		local_save_flags(flags);
-		local_irq_enable_in_hardirq();
+		if (!irqs_threaded) {
+			local_save_flags(flags);
+			local_irq_enable_in_hardirq();
+		}
 		timeout += jiffies;
 		while ((stat = tp_ops->read_status(hwif)) & ATA_BUSY) {
 			if (time_after(jiffies, timeout)) {
@@ -129,12 +132,14 @@ int __ide_wait_stat(ide_drive_t *drive, u8 good, u8 bad,
 				if ((stat & ATA_BUSY) == 0)
 					break;
 
-				local_irq_restore(flags);
+				if (!irqs_threaded)
+					local_irq_restore(flags);
 				*rstat = stat;
 				return -EBUSY;
 			}
 		}
-		local_irq_restore(flags);
+		if (!irqs_threaded)
+			local_irq_restore(flags);
 	}
 	/*
 	 * Allow status to settle, then read it again.
diff --git a/drivers/ide/ide-taskfile.c b/drivers/ide/ide-taskfile.c
index 49f9b4739779..d42feeaebd36 100644
--- a/drivers/ide/ide-taskfile.c
+++ b/drivers/ide/ide-taskfile.c
@@ -405,7 +405,7 @@ static ide_startstop_t pre_task_out_intr(ide_drive_t *drive,
 		return startstop;
 	}
 
-	if ((drive->dev_flags & IDE_DFLAG_UNMASK) == 0)
+	if (!force_irqthreads && (drive->dev_flags & IDE_DFLAG_UNMASK) == 0)
 		local_irq_disable();
 
 	ide_set_handler(drive, &task_pio_intr, WAIT_WORSTCASE);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index e3336d904f64..4c2ef8084e32 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -24,6 +24,7 @@
 
 #ifdef CONFIG_IRQ_FORCED_THREADING
 __read_mostly bool force_irqthreads;
+EXPORT_SYMBOL_GPL(force_irqthreads);
 
 static int __init setup_forced_irqthreads(char *arg)
 {
-- 
2.17.0