[PATCH] media: cx18: Disable PCI device on probe failure

[Myeonghun Pak <mhun512@gmail.com>]

cx18_setup_pci() enables the PCI device but does not disable it when
DMA mask setup or the memory-region reservation fails. Later probe
failure paths release the region without balancing the enable either.

Unwind the enable inside cx18_setup_pci() when that helper fails after
enabling the device. Once setup succeeds, disable it in the probe
cleanup after releasing the memory region. Setup failures skip that
cleanup, so each successful enable is balanced exactly once.

Keep the existing error codes and normal removal path unchanged.

This issue was identified during our ongoing static-analysis research
while reviewing kernel code.

Fixes: 1c1e45d17b66 ("V4L/DVB (7786): cx18: new driver for the Conexant CX23418 MPEG encoder chip")
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
Assisted-by: OpenAI:GPT-5.6
---
Validated with an ARM64 W=1 object build and strict checkpatch.
No hardware runtime or probe-failure injection testing was performed.

 drivers/media/pci/cx18/cx18-driver.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/media/pci/cx18/cx18-driver.c b/drivers/media/pci/cx18/cx18-driver.c
index 214fac7..ac90ce6 100644
--- a/drivers/media/pci/cx18/cx18-driver.c
+++ b/drivers/media/pci/cx18/cx18-driver.c
@@ -805,12 +805,12 @@ static int cx18_setup_pci(struct cx18 *cx, struct pci_dev *pci_dev,
 	}
 	if (dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(32))) {
 		CX18_ERR("No suitable DMA available, card %d\n", cx->instance);
-		return -EIO;
+		goto err_disable_device;
 	}
 	if (!request_mem_region(cx->base_addr, CX18_MEM_SIZE, "cx18 encoder")) {
 		CX18_ERR("Cannot request encoder memory region, card %d\n",
 			 cx->instance);
-		return -EIO;
+		goto err_disable_device;
 	}
 
 	/* Enable bus mastering and memory mapped IO for the CX23418 */
@@ -834,6 +834,10 @@ static int cx18_setup_pci(struct cx18 *cx, struct pci_dev *pci_dev,
 		   cx->pci_dev->irq, pci_latency, (u64)cx->base_addr);
 
 	return 0;
+
+err_disable_device:
+	pci_disable_device(pci_dev);
+	return -EIO;
 }
 
 static void cx18_init_subdevs(struct cx18 *cx)
@@ -1120,6 +1124,7 @@ free_map:
 	cx18_iounmap(cx);
 free_mem:
 	release_mem_region(cx->base_addr, CX18_MEM_SIZE);
+	pci_disable_device(pci_dev);
 free_workqueues:
 	destroy_workqueue(cx->in_work_queue);
 err: