[PATCH] libata-sff: use spin_lock_irqsave instead of spin_lock_irq in IRQ context.

[Fuqian Huang]

Function ata_sff_flush_pio_task use spin_lock_irq/spin_unlock_irq
to protect shared data.
spin_unlock_irq will enable interrupts.

In the interrupt handler nv_swncq_interrupt (./drivers/ata/sata_nv.c),
when ap->link.sactive is true, nv_swncq_host_interrupt was called.
nv_swncq_hotplug is called when NV_SWNCQ_IRQ_HOTPLUG is set.
Then it will follow this chain:
nv_swncq_hotplug -> sata_scr_read (./dirvers/ata/libata-core.c)
 -> sata_pmp_scr_read (./drivers/ata/libata-pmp.c)
 -> sata_pmp_read -> ata_exec_internal 
 -> ata_exec_internal_sg -> ata_sff_flush_pio_task

Interrupts are enabled in interrupt handler.
Use spin_lock_irqsave instead of spin_lock_irq to avoid this.

Signed-off-by: Fuqian Huang <huangfq.dax...@gmail.com>
---
 drivers/ata/libata-sff.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 10aa27882142..d3143e7e6ec0 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -1241,6 +1241,7 @@ EXPORT_SYMBOL_GPL(ata_sff_queue_pio_task);
 
 void ata_sff_flush_pio_task(struct ata_port *ap)
 {
+       unsigned long flags;
        DPRINTK("ENTER\n");
 
        cancel_delayed_work_sync(&ap->sff_pio_task);
@@ -1253,9 +1254,9 @@ void ata_sff_flush_pio_task(struct ata_port *ap)
         * __ata_sff_port_intr() checks for HSM_ST_IDLE and before it calls
         * ata_sff_hsm_move() causing ata_sff_hsm_move() to BUG().
         */
-       spin_lock_irq(ap->lock);
+       spin_lock_irqsave(ap->lock, flags);
        ap->hsm_task_state = HSM_ST_IDLE;
-       spin_unlock_irq(ap->lock);
+       spin_unlock_irqrestore(ap->lock, flags);
 
        ap->sff_pio_task_link = NULL;
 
-- 
2.11.0