[PATCH RESEND] dmaengine: bestcomm: Fix exception handling in bcom_task_alloc()

[Markus Elfring]

From: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
Date: Sat, 18 Mar 2023 14:55:02 +0100

The label “error” was used to jump to another pointer check despite of
the detail in the implementation of the function “bcom_task_alloc”
that it was determined already that the corresponding variable
contained a null pointer (because of a failed memory allocation).

1. Use more appropriate labels instead.

2. Reorder jump targets at the end.

3. Omit a questionable call of the function “bcom_sram_free”

4. Delete an extra pointer check which became unnecessary
   with this refactoring.


This issue was detected by using the Coccinelle software.

Fixes: 2f9ea1bde0d1 ("[POWERPC] bestcomm: core bestcomm support for Freescale MPC5200")
Signed-off-by: Markus Elfring <elfring@xxxxxxxxxxxxxxxxxxxxx>
---
 drivers/dma/bestcomm/bestcomm.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/dma/bestcomm/bestcomm.c b/drivers/dma/bestcomm/bestcomm.c
index eabbcfcaa7cb..7d6a92d34871 100644
--- a/drivers/dma/bestcomm/bestcomm.c
+++ b/drivers/dma/bestcomm/bestcomm.c
@@ -72,7 +72,7 @@ bcom_task_alloc(int bd_count, int bd_size, int priv_size)
 	/* Allocate our structure */
 	tsk = kzalloc(sizeof(struct bcom_task) + priv_size, GFP_KERNEL);
 	if (!tsk)
-		goto error;
+		goto reset_stop;

 	tsk->tasknum = tasknum;
 	if (priv_size)
@@ -81,18 +81,18 @@ bcom_task_alloc(int bd_count, int bd_size, int priv_size)
 	/* Get IRQ of that task */
 	tsk->irq = irq_of_parse_and_map(bcom_eng->ofnode, tsk->tasknum);
 	if (!tsk->irq)
-		goto error;
+		goto free_task;

 	/* Init the BDs, if needed */
 	if (bd_count) {
 		tsk->cookie = kmalloc_array(bd_count, sizeof(void *),
 					    GFP_KERNEL);
 		if (!tsk->cookie)
-			goto error;
+			goto dispose_mapping;

 		tsk->bd = bcom_sram_alloc(bd_count * bd_size, 4, &tsk->bd_pa);
 		if (!tsk->bd)
-			goto error;
+			goto free_cookie;
 		memset_io(tsk->bd, 0x00, bd_count * bd_size);

 		tsk->num_bd = bd_count;
@@ -101,15 +101,13 @@ bcom_task_alloc(int bd_count, int bd_size, int priv_size)

 	return tsk;

-error:
-	if (tsk) {
-		if (tsk->irq)
-			irq_dispose_mapping(tsk->irq);
-		bcom_sram_free(tsk->bd);
-		kfree(tsk->cookie);
-		kfree(tsk);
-	}
-
+free_cookie:
+	kfree(tsk->cookie);
+dispose_mapping:
+	irq_dispose_mapping(tsk->irq);
+free_task:
+	kfree(tsk);
+reset_stop:
 	bcom_eng->tdt[tasknum].stop = 0;

 	return NULL;
--
2.40.0