* [PATCH] usb: gadget: function: Replace GFP_KERNEL with GFP_ATOMIC
@ 2015-02-20 13:05 Tapasweni Pathak
2015-02-20 17:09 ` Michal Nazarewicz
0 siblings, 1 reply; 2+ messages in thread
From: Tapasweni Pathak @ 2015-02-20 13:05 UTC (permalink / raw)
To: balbi, gregkh, mina86, r.baldyga, andrzej.p, linux-usb, linux-kernel
Cc: tapaswenipathak, julia.lawall
To avoid deadlock, do not call blocking functions with spinlocks held.
Replace GFP_KERNEL with GFP_ATOMIC, as the latter will fail if the heap
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/usb/gadget/function/f_fs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index af98b09..8a25d30 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -823,7 +823,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
}
if (io_data->aio) {
- req = usb_ep_alloc_request(ep->ep, GFP_KERNEL);
+ req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC);
if (unlikely(!req))
goto error_lock;
--
1.7.9.5
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] usb: gadget: function: Replace GFP_KERNEL with GFP_ATOMIC
2015-02-20 13:05 [PATCH] usb: gadget: function: Replace GFP_KERNEL with GFP_ATOMIC Tapasweni Pathak
@ 2015-02-20 17:09 ` Michal Nazarewicz
0 siblings, 0 replies; 2+ messages in thread
From: Michal Nazarewicz @ 2015-02-20 17:09 UTC (permalink / raw)
To: Tapasweni Pathak, balbi, gregkh, r.baldyga, andrzej.p, linux-usb,
linux-kernel
Cc: tapaswenipathak, julia.lawall
On Fri, Feb 20 2015, 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 heap
> 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?
I think there is. A patchset will follow this reply.
> drivers/usb/gadget/function/f_fs.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
> index af98b09..8a25d30 100644
> --- a/drivers/usb/gadget/function/f_fs.c
> +++ b/drivers/usb/gadget/function/f_fs.c
> @@ -823,7 +823,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)
> }
>
> if (io_data->aio) {
> - req = usb_ep_alloc_request(ep->ep, GFP_KERNEL);
> + req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC);
> if (unlikely(!req))
> goto error_lock;
>
--
Best regards, _ _
.o. | Liege of Serenely Enlightened Majesty of o' \,=./ `o
..o | Computer Science, Michał “mina86” Nazarewicz (o o)
ooo +--<mpn@google.com>--<xmpp:mina86@jabber.org>--ooO--(_)--Ooo--
^ permalink raw reply [flat|nested] 2+ messages in thread
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2015-02-20 13:05 [PATCH] usb: gadget: function: Replace GFP_KERNEL with GFP_ATOMIC Tapasweni Pathak
2015-02-20 17:09 ` Michal Nazarewicz
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