[PATCH] staging: emxx_udc: Replace GFP_KERNEL with GFP_ATOMIC

[PATCH] staging: emxx_udc: Replace GFP_KERNEL with GFP_ATOMIC

[Tapasweni Pathak]

To avoid deadlock, do not call blocking functions with spinlocks held.

Replace GFP_KERNEL with GFP_ATOMIC, as the latter will fail if the pile
doesn't have enough free pages but will not sleep and hence deadlock can
be avoided.

Found by Coccinelle.

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
---
Is there any other way this can be fixed as it is better to avoid GFP_ATOMIC?

 drivers/staging/emxx_udc/emxx_udc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/emxx_udc/emxx_udc.c b/drivers/staging/emxx_udc/emxx_udc.c
index 4be646c..6c1de27 100644
--- a/drivers/staging/emxx_udc/emxx_udc.c
+++ b/drivers/staging/emxx_udc/emxx_udc.c
@@ -2794,7 +2794,7 @@ static int nbu2ss_ep_queue(
 		if (ep->virt_buf == NULL)
 			ep->virt_buf = (u8 *)dma_alloc_coherent(
 				NULL, PAGE_SIZE,
-				&ep->phys_buf, GFP_KERNEL | GFP_DMA);
+				&ep->phys_buf, GFP_ATOMIC | GFP_DMA);
 		if (ep->epnum > 0)  {
 			if (ep->direct == USB_DIR_IN)
 				memcpy(ep->virt_buf, req->req.buf,
--
1.7.9.5

Re: [PATCH] staging: emxx_udc: Replace GFP_KERNEL with GFP_ATOMIC

[Greg KH]

On Fri, Feb 20, 2015 at 06:43:53PM +0530, Tapasweni Pathak wrote:
> To avoid deadlock, do not call blocking functions with spinlocks held.
> 
> Replace GFP_KERNEL with GFP_ATOMIC, as the latter will fail if the pile
> doesn't have enough free pages but will not sleep and hence deadlock can
> be avoided.
> 
> Found by Coccinelle.
> 
> Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
> ---
> Is there any other way this can be fixed as it is better to avoid GFP_ATOMIC?

No, this is fine, nice fix.

thanks,

greg k-h