dmaengine: idxd: cdev: Fix uninitialized use of sva in idxd_cdev_open

Fix Smatch-detected issue:
drivers/dma/idxd/cdev.c:321 idxd_cdev_open() error:
uninitialized symbol 'sva'.

'sva' pointer may be used uninitialized in error handling paths.
Specifically, if PASID support is enabled and iommu_sva_bind_device()
returns an error, the code jumps to the cleanup label and attempts to
call iommu_sva_unbind_device(sva) without ensuring that sva was
successfully assigned. This triggers a Smatch warning about an
uninitialized symbol.

Initialize sva to NULL at declaration and add a check using
IS_ERR_OR_NULL() before unbinding the device. This ensures the
function does not use an invalid or uninitialized pointer during
cleanup.

Signed-off-by: Purva Yeshi <purvayeshi550@gmail.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Link: https://lore.kernel.org/r/20250410110216.21592-1-purvayeshi550@gmail.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/idxd/cdev.c

@@ -222,7 +222,7 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
 	struct idxd_wq *wq;
 	struct device *dev, *fdev;
 	int rc = 0;
-	struct iommu_sva *sva;
+	struct iommu_sva *sva = NULL;
 	unsigned int pasid;
 	struct idxd_cdev *idxd_cdev;
 
@@ -317,7 +317,7 @@ static int idxd_cdev_open(struct inode *inode, struct file *filp)
 	if (device_user_pasid_enabled(idxd))
 		idxd_xa_pasid_remove(ctx);
 failed_get_pasid:
-	if (device_user_pasid_enabled(idxd))
+	if (device_user_pasid_enabled(idxd) && !IS_ERR_OR_NULL(sva))
 		iommu_sva_unbind_device(sva);
 failed:
 	mutex_unlock(&wq->wq_lock);