diff mbox series

[1/2] dmaengine: pxa_dma: Remove an erroneous BUG_ON() in pxad_free_desc()

Message ID c8fc5563c9593c914fde41f0f7d1489a21b45a9a.1696676782.git.christophe.jaillet@wanadoo.fr
State New
Headers
Series [1/2] dmaengine: pxa_dma: Remove an erroneous BUG_ON() in pxad_free_desc() |

Commit Message

Christophe JAILLET Oct. 7, 2023, 11:13 a.m. UTC 
  If pxad_alloc_desc() fails on the first dma_pool_alloc() call, then
sw_desc->nb_desc is zero.
In such a case pxad_free_desc() is called and it will BUG_ON().

Remove this erroneous BUG_ON().

It is also useless, because if "sw_desc->nb_desc == 0", then, on the first
iteration of the for loop, i is -1 and the loop will not be executed.
(both i and sw_desc->nb_desc are 'int')

Fixes: a57e16cf0333 ("dmaengine: pxa: add pxa dmaengine driver")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
---
 drivers/dma/pxa_dma.c | 1 -
 1 file changed, 1 deletion(-)

Comments

Kees Cook Oct. 8, 2023, 9:03 p.m. UTC | #1 
On Sat, Oct 07, 2023 at 01:13:09PM +0200, Christophe JAILLET wrote:
> If pxad_alloc_desc() fails on the first dma_pool_alloc() call, then
> sw_desc->nb_desc is zero.
> In such a case pxad_free_desc() is called and it will BUG_ON().
> 
> Remove this erroneous BUG_ON().

Perhaps it could be changed to a WARN_ON()?

> It is also useless, because if "sw_desc->nb_desc == 0", then, on the first
> iteration of the for loop, i is -1 and the loop will not be executed.
> (both i and sw_desc->nb_desc are 'int')

Agreed.

> 
> Fixes: a57e16cf0333 ("dmaengine: pxa: add pxa dmaengine driver")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
>  drivers/dma/pxa_dma.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
> index 3c574dc0613b..94cef2905940 100644
> --- a/drivers/dma/pxa_dma.c
> +++ b/drivers/dma/pxa_dma.c
> @@ -722,7 +722,6 @@ static void pxad_free_desc(struct virt_dma_desc *vd)
>  	dma_addr_t dma;
>  	struct pxad_desc_sw *sw_desc = to_pxad_sw_desc(vd);
>  
> -	BUG_ON(sw_desc->nb_desc == 0);
>  	for (i = sw_desc->nb_desc - 1; i >= 0; i--) {
>  		if (i > 0)
>  			dma = sw_desc->hw_desc[i - 1]->ddadr;
> -- 
> 2.34.1
>
Vinod Koul Oct. 9, 2023, 6:12 a.m. UTC | #2 
On Sat, 07 Oct 2023 13:13:09 +0200, Christophe JAILLET wrote:
> If pxad_alloc_desc() fails on the first dma_pool_alloc() call, then
> sw_desc->nb_desc is zero.
> In such a case pxad_free_desc() is called and it will BUG_ON().
> 
> Remove this erroneous BUG_ON().
> 
> It is also useless, because if "sw_desc->nb_desc == 0", then, on the first
> iteration of the for loop, i is -1 and the loop will not be executed.
> (both i and sw_desc->nb_desc are 'int')
> 
> [...]

Applied, thanks!

[1/2] dmaengine: pxa_dma: Remove an erroneous BUG_ON() in pxad_free_desc()
      commit: 83c761f568733277ce1f7eb9dc9e890649c29a8c
[2/2] dmaengine: pxa_dma: Annotate struct pxad_desc_sw with __counted_by
      commit: 0481291f0ccbc5147635cf0eb108f9fe5a05ee7d

Best regards,
diff mbox series

Patch

diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index 3c574dc0613b..94cef2905940 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -722,7 +722,6 @@  static void pxad_free_desc(struct virt_dma_desc *vd)
 	dma_addr_t dma;
 	struct pxad_desc_sw *sw_desc = to_pxad_sw_desc(vd);
 
-	BUG_ON(sw_desc->nb_desc == 0);
 	for (i = sw_desc->nb_desc - 1; i >= 0; i--) {
 		if (i > 0)
 			dma = sw_desc->hw_desc[i - 1]->ddadr;