linux-kernel - [PATCH v2 2/4] media: chips-media: wave5: Avoid race condition for interrupt handling

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Message-Id: <20241217045125.58-3-jackson.lee@chipsnmedia.com>
Date: Tue, 17 Dec 2024 13:51:23 +0900
From: "Jackson.lee" <jackson.lee@...psnmedia.com>
To: mchehab@...nel.org,
	hverkuil-cisco@...all.nl,
	sebastian.fricke@...labora.com,
	nicolas.dufresne@...labora.com,
	bob.beckett@...labora.com,
	dafna.hirschfeld@...labora.com
Cc: linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	jackson.lee@...psnmedia.com,
	lafley.kim@...psnmedia.com,
	b-brnich@...com,
	hverkuil@...all.nl,
	nas.chung@...psnmedia.com
Subject: [PATCH v2 2/4] media: chips-media: wave5: Avoid race condition for interrupt handling

In case of multi instance, interrupts can occur for other instances as
soon as interrupt is cleared. If driver reads the instance_info after
clearing the interrupt, it is not guaranteed that the instance_info is
valid for the current interrupt.

Read the instance_info register for each interrupt before clearing the
interrupt.

Signed-off-by: Jackson.lee <jackson.lee@...psnmedia.com>
Signed-off-by: Nas Chung <nas.chung@...psnmedia.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
---
 drivers/media/platform/chips-media/wave5/wave5-vpu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpu.c b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
index 6b294a2d6717..63a607d10433 100644
--- a/drivers/media/platform/chips-media/wave5/wave5-vpu.c
+++ b/drivers/media/platform/chips-media/wave5/wave5-vpu.c
@@ -55,12 +55,12 @@ static void wave5_vpu_handle_irq(void *dev_id)
 	struct vpu_device *dev = dev_id;
 
 	irq_reason = wave5_vdi_read_register(dev, W5_VPU_VINT_REASON);
+	seq_done = wave5_vdi_read_register(dev, W5_RET_SEQ_DONE_INSTANCE_INFO);
+	cmd_done = wave5_vdi_read_register(dev, W5_RET_QUEUE_CMD_DONE_INST);
 	wave5_vdi_write_register(dev, W5_VPU_VINT_REASON_CLR, irq_reason);
 	wave5_vdi_write_register(dev, W5_VPU_VINT_CLEAR, 0x1);
 
 	list_for_each_entry(inst, &dev->instances, list) {
-		seq_done = wave5_vdi_read_register(dev, W5_RET_SEQ_DONE_INSTANCE_INFO);
-		cmd_done = wave5_vdi_read_register(dev, W5_RET_QUEUE_CMD_DONE_INST);
 
 		if (irq_reason & BIT(INT_WAVE5_INIT_SEQ) ||
 		    irq_reason & BIT(INT_WAVE5_ENC_SET_PARAM)) {
-- 
2.43.0