[PATCH v7 05/19] media: meson: vdec: Fix race condition and synchronize esparser IRQ

During session teardown sequences in vdec_stop_streaming() and
vdec_close(), the 'esparser' hardware interrupt handler can still be
actively triggered or executing on another CPU core. This creates a
transient race condition where the ISR attempts to handle stream data and
allocate internal tracking state structures after session contexts have
been modified or freed.

Update esparser_isr() to read the current session context utilizing an
smp_load_acquire() barrier snapshot. If the pointer resolves to NULL,
terminate processing early with IRQ_HANDLED to protect against
concurrent dismantling.

Suggested-by: Doruk Tan Ozturk <[email protected]>
Reported-by: Sashiko <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Anand Moon <[email protected]>
---
 drivers/staging/media/meson/vdec/esparser.c | 8 ++++++++
 drivers/staging/media/meson/vdec/vdec.c     | 4 ++++
 drivers/staging/media/meson/vdec/vdec.h     | 2 ++
 3 files changed, 14 insertions(+)

diff --git a/drivers/staging/media/meson/vdec/esparser.c b/drivers/staging/media/meson/vdec/esparser.c
index 4632346f04a9e..37749ede308c6 100644
--- a/drivers/staging/media/meson/vdec/esparser.c
+++ b/drivers/staging/media/meson/vdec/esparser.c
@@ -60,6 +60,12 @@ static irqreturn_t esparser_isr(int irq, void *dev)
 {
 	int int_status;
 	struct amvdec_core *core = dev;
+	struct amvdec_session *sess;
+
+	/* Secure an atomic snapshot to protect against concurrent teardown */
+	sess = smp_load_acquire(&core->cur_sess);
+	if (!sess)
+		return IRQ_HANDLED;
 
 	int_status = amvdec_read_parser(core, PARSER_INT_STATUS);
 	amvdec_write_parser(core, PARSER_INT_STATUS, int_status);
@@ -439,6 +445,8 @@ int esparser_init(struct platform_device *pdev, struct amvdec_core *core)
 	if (irq < 0)
 		return irq;
 
+	core->esparser_irq = irq;
+
 	ret = devm_request_irq(dev, irq, esparser_isr, IRQF_SHARED,
 			       "esparserirq", core);
 	if (ret) {
diff --git a/drivers/staging/media/meson/vdec/vdec.c b/drivers/staging/media/meson/vdec/vdec.c
index 7ae3d5a9dd6ab..7689ffdb2e500 100644
--- a/drivers/staging/media/meson/vdec/vdec.c
+++ b/drivers/staging/media/meson/vdec/vdec.c
@@ -486,6 +486,8 @@ static void vdec_stop_streaming(struct vb2_queue *q)
 
 		/* Synchronize and flush pending hardware interrupt service routines */
 		synchronize_irq(core->vdec_irq);
+		/* Ensure esparser ISR finishes executing */
+		synchronize_irq(core->esparser_irq);
 
 		vdec_poweroff(sess);
 		vdec_free_canvas(sess);
@@ -994,6 +996,8 @@ static int vdec_close(struct file *file)
 
 	/* Synchronize and flush pending hardware interrupt service routines */
 	synchronize_irq(core->vdec_irq);
+	/* Ensure esparser ISR finishes executing */
+	synchronize_irq(core->esparser_irq);
 
 	if (!IS_ERR_OR_NULL(sess->recycle_thread)) {
 		kthread_stop(sess->recycle_thread);
diff --git a/drivers/staging/media/meson/vdec/vdec.h b/drivers/staging/media/meson/vdec/vdec.h
index d165c343fd022..c4639cf33e73e 100644
--- a/drivers/staging/media/meson/vdec/vdec.h
+++ b/drivers/staging/media/meson/vdec/vdec.h
@@ -68,6 +68,7 @@ struct amvdec_session;
  * @cur_sess: current decoding session
  * @lock: video device lock
  * @vdec_irq: irq for video decoding
+ * @esparser_irq: irq for elementary stream parsing
  */
 struct amvdec_core {
 	void __iomem *dos_base;
@@ -95,6 +96,7 @@ struct amvdec_core {
 	struct amvdec_session *cur_sess;
 	struct mutex lock;
 	int vdec_irq;
+	int esparser_irq;
 };
 
 /**
-- 
2.50.1


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