[PATCH] ARM: vic: re-read status register before dispatching each IRQ handler

[will.deacon@arm.com (Will Deacon)]

handle_IRQ may briefly cause interrupts to be re-enabled during soft IRQ
processing on the exit path, leading to nested handling of VIC interrupts.

Since the current code does not re-read the VIC_IRQ_STATUS register, this
can lead to multiple invocations of the same interrupt handler and
spurious interrupts to be reported.

This patch changes the VIC interrupt dispatching code to re-read the
status register each time, avoiding duplicate invocations of the same
handler.

Acked-and-tested-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---

Taken against v3.4-rc1 and tested on Versatile AB 926 (+ PL011 NULL
pointer fix). I'll put this in the patch system tomorrow if there aren't
any objections.

 arch/arm/common/vic.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/arch/arm/common/vic.c b/arch/arm/common/vic.c
index 7a66311..6b1de5d 100644
--- a/arch/arm/common/vic.c
+++ b/arch/arm/common/vic.c
@@ -435,11 +435,9 @@ static int handle_one_vic(struct vic_device *vic, struct pt_regs *regs)
 	u32 stat, irq;
 	int handled = 0;
 
-	stat = readl_relaxed(vic->base + VIC_IRQ_STATUS);
-	while (stat) {
+	while ((stat = readl_relaxed(vic->base + VIC_IRQ_STATUS))) {
 		irq = ffs(stat) - 1;
 		handle_IRQ(irq_find_mapping(vic->domain, irq), regs);
-		stat &= ~(1 << irq);
 		handled = 1;
 	}
 
-- 
1.7.4.1