[PATCH 2/2] media: ipu6: Only call the isys and psys ISRs for their own interrupts

[Felipe Calliari <calliarifelipe@gmail.com>]

ipu6_buttress_isr() calls the isys and psys ISRs on every buttress
interrupt, and only afterwards checks whether the interrupt was theirs.
So each isys interrupt also runs the psys ISR, and each psys interrupt
runs the isys ISR, only to have the result discarded.

Beyond the wasted work, this makes an interrupt for one device
dereference the other device's hooks. After intel_ipu6_psys is unloaded,
its adev->auxdrv_data still points into the unloaded module, and every
isys interrupt, e.g. on the next stream, calls through it. This matches
a hard lockup without a trace reported on the first stream after
unloading the psys driver. On a Samsung Galaxy Book3 Ultra,
instrumenting the ISR showed that a 60-frame capture after
"rmmod intel_ipu6_psys" would have made at least ten calls through the
stale psys hooks. The same capture made none with this change, and
captured all 60 frames.

Check the interrupt status bit before calling the ISR.

Reported-by: Mars-Wave <tmorolias@gmail.com>
Closes: https://lore.kernel.org/linux-media/20260922063507.690-1-tmorolias@gmail.com/
Fixes: ab29a2478e70 ("media: intel/ipu6: add IPU6 buttress interface driver")
Cc: stable@vger.kernel.org
Signed-off-by: Felipe Calliari <calliarifelipe@gmail.com>
---
 drivers/media/pci/intel/ipu6/ipu6-buttress.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/media/pci/intel/ipu6/ipu6-buttress.c b/drivers/media/pci/intel/ipu6/ipu6-buttress.c
index 63197f746..74c191d72 100644
--- a/drivers/media/pci/intel/ipu6/ipu6-buttress.c
+++ b/drivers/media/pci/intel/ipu6/ipu6-buttress.c
@@ -369,11 +369,13 @@ irqreturn_t ipu6_buttress_isr(int irq, void *isp_ptr)
 		writel(irq_status, isp->base + regs->irq_clear);
 
 		for (i = 0; i < ARRAY_SIZE(adev_irq_mask); i++) {
-			irqreturn_t r = ipu6_buttress_call_isr(adev[i]);
+			irqreturn_t r;
 
 			if (!(irq_status & adev_irq_mask[i]))
 				continue;
 
+			r = ipu6_buttress_call_isr(adev[i]);
+
 			if (r == IRQ_WAKE_THREAD) {
 				ret = IRQ_WAKE_THREAD;
 				disable_irqs |= adev_irq_mask[i];
-- 
2.55.0