dmaengine: idxd: make submit failure path consistent on desc freeing

The submission path for dmaengine API does not do descriptor freeing on
failure. Also, with the abort mechanism, the freeing of descriptor happens
when the abort callback is completed. Therefore free descriptor on all
error paths for submission call to make things consistent. Also remove the
double free that would happen on abort in idxd_dma_tx_submit() call.

Fixes: 6b4b87f ("dmaengine: idxd: fix submission race window")
Signed-off-by: Dave Jiang <[email protected]>
Link: https://lore.kernel.org/r/162827146072.3459011.10255348500504659810.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <[email protected]>

Author: davejiang

drivers/dma/idxd/dma.c

@@ -149,10 +149,8 @@ static dma_cookie_t idxd_dma_tx_submit(struct dma_async_tx_descriptor *tx)
 	cookie = dma_cookie_assign(tx);
 
 	rc = idxd_submit_desc(wq, desc);
-	if (rc < 0) {
-		idxd_free_desc(wq, desc);
+	if (rc < 0)
 		return rc;
-	}
 
 	return cookie;
 }

drivers/dma/idxd/submit.c

@@ -139,11 +139,15 @@ int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
 	void __iomem *portal;
 	int rc;
 
-	if (idxd->state != IDXD_DEV_ENABLED)
+	if (idxd->state != IDXD_DEV_ENABLED) {
+		idxd_free_desc(wq, desc);
 		return -EIO;
+	}
 
-	if (!percpu_ref_tryget_live(&wq->wq_active))
+	if (!percpu_ref_tryget_live(&wq->wq_active)) {
+		idxd_free_desc(wq, desc);
 		return -ENXIO;
+	}
 
 	portal = idxd_wq_portal_addr(wq);
 
@@ -175,8 +179,11 @@ int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
 		rc = enqcmds(portal, desc->hw);
 		if (rc < 0) {
 			percpu_ref_put(&wq->wq_active);
+			/* abort operation frees the descriptor */
 			if (ie)
 				llist_abort_desc(wq, ie, desc);
+			else
+				idxd_free_desc(wq, desc);
 			return rc;
 		}
 	}