From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755170AbbBTRJj (ORCPT ); Fri, 20 Feb 2015 12:09:39 -0500 Received: from mail-wi0-f171.google.com ([209.85.212.171]:50889 "EHLO mail-wi0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754550AbbBTRJg convert rfc822-to-8bit (ORCPT ); Fri, 20 Feb 2015 12:09:36 -0500 From: Michal Nazarewicz To: Tapasweni Pathak , balbi@ti.com, gregkh@linuxfoundation.org, r.baldyga@samsung.com, andrzej.p@samsung.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Cc: tapaswenipathak@gmail.com, julia.lawall@lip6.fr Subject: Re: [PATCH] usb: gadget: function: Replace GFP_KERNEL with GFP_ATOMIC In-Reply-To: <20150220130524.GA22598@kt-Inspiron-3542> Organization: http://mina86.com/ References: <20150220130524.GA22598@kt-Inspiron-3542> User-Agent: Notmuch/0.19+53~g2e63a09 (http://notmuchmail.org) Emacs/25.0.50.1 (x86_64-unknown-linux-gnu) X-Face: PbkBB1w#)bOqd`iCe"Ds{e+!C7`pkC9a|f)Qo^BMQvy\q5x3?vDQJeN(DS?|-^$uMti[3D*#^_Ts"pU$jBQLq~Ud6iNwAw_r_o_4]|JO?]}P_}Nc&"p#D(ZgUb4uCNPe7~a[DbPG0T~!&c.y$Ur,=N4RT>]dNpd;KFrfMCylc}gc??'U2j,!8%xdD Face: 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 X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 X-Hashcash: 1:20:150220:linux-usb@vger.kernel.org::t2++7cZwm7nspj+4:0000000000000000000000000000000000000sgs X-Hashcash: 1:20:150220:andrzej.p@samsung.com::pBpHiVUlr3oP65Oo:00000000000000000000000000000000000000001bie X-Hashcash: 1:20:150220:gregkh@linuxfoundation.org::RDVj7YOqJIvuOj1C:000000000000000000000000000000000002Rqz X-Hashcash: 1:20:150220:balbi@ti.com::Kq+hJgWeZZSLVNXa:0000043uV X-Hashcash: 1:20:150220:tapaswenipathak@gmail.com::WmXbDjrPhY7j2zWG:0000000000000000000000000000000000004Elm X-Hashcash: 1:20:150220:tapaswenipathak@gmail.com::ybdwRac32wH59tAx:0000000000000000000000000000000000005g67 X-Hashcash: 1:20:150220:julia.lawall@lip6.fr::JFruH2TouWZa9ciZ:000000000000000000000000000000000000000004OoI X-Hashcash: 1:20:150220:r.baldyga@samsung.com::TjjOyp4L6SJ57Ai4:00000000000000000000000000000000000000009M0U X-Hashcash: 1:20:150220:linux-kernel@vger.kernel.org::5Wjp/DCjSyIEy23t:000000000000000000000000000000000EFmj Date: Fri, 20 Feb 2015 18:09:32 +0100 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 > --- > 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 +------ooO--(_)--Ooo--