From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Kacur Subject: Re: [PATCH] input: remove BKL from uinput open function Date: Mon, 1 Feb 2010 21:22:01 +0100 Message-ID: <520f0cf11002011222h134dbf06rf1db612da9a9728@mail.gmail.com> References: <1264800197-29523-1-git-send-email-cascardo@holoscopio.com> <201001302257.09354.arnd@arndb.de> <520f0cf11001301507k20e3cf8dqa73026e12f3a1767@mail.gmail.com> <201001310520.55813.arnd@arndb.de> <20100131052942.GA12320@core.coreip.homeip.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail-ew0-f228.google.com ([209.85.219.228]:46850 "EHLO mail-ew0-f228.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754821Ab0BAUWD convert rfc822-to-8bit (ORCPT ); Mon, 1 Feb 2010 15:22:03 -0500 In-Reply-To: <20100131052942.GA12320@core.coreip.homeip.net> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Dmitry Torokhov Cc: Arnd Bergmann , Thadeu Lima de Souza Cascardo , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org On Sun, Jan 31, 2010 at 6:29 AM, Dmitry Torokhov wrote: > On Sun, Jan 31, 2010 at 05:20:55AM +0100, Arnd Bergmann wrote: >> On Sunday 31 January 2010, John Kacur wrote: >> > > Sorry, I should have been clearer, but not implementing llseek >> > > is the problem I was referring to: When a driver has no explicit >> > > .llseek operation in its file operations and does not call >> > > nonseekable_open from its open operation, the VFS layer will >> > > implicitly use default_llseek, which takes the BKL. We're >> > > in the process of changing drivers not to do this, one by one >> > > so we can kill the BKL in the end. >> > > >> > >> > I know we've discussed this before, but why wouldn't the following >> > make more sense? >> > =A0.llseek =A0 =A0 =A0 =A0 =3D no_llseek, >> >> That's one of the possible solutions. Assigning it to generic_file_l= lseek >> also gets rid of the BKL but keeps the current behaviour (calling se= ek >> returns success without having an effect, no_llseek returns -ESPIPE)= , >> while calling nonseekable_open has the other side-effect of making >> pread/pwrite fail with -ESPIPE, which is more consistent than >> only failing seek. >> > > OK, so how about the patch below (on top of Thadeu's patch)? > > -- > Dmitry > > Input: uinput - use nonseekable_open > > Seeking does not make sense for uinput so let's use nonseekable_open > to mark the device non-seekable. > > Signed-off-by: Dmitry Torokhov > --- > > =A0drivers/input/misc/uinput.c | =A0 =A07 +++++++ > =A01 files changed, 7 insertions(+), 0 deletions(-) > > > diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.= c > index 18206e1..7089151 100644 > --- a/drivers/input/misc/uinput.c > +++ b/drivers/input/misc/uinput.c > @@ -278,6 +278,7 @@ static int uinput_create_device(struct uinput_dev= ice *udev) > =A0static int uinput_open(struct inode *inode, struct file *file) > =A0{ > =A0 =A0 =A0 =A0struct uinput_device *newdev; > + =A0 =A0 =A0 int error; > > =A0 =A0 =A0 =A0newdev =3D kzalloc(sizeof(struct uinput_device), GFP_K= ERNEL); > =A0 =A0 =A0 =A0if (!newdev) > @@ -291,6 +292,12 @@ static int uinput_open(struct inode *inode, stru= ct file *file) > > =A0 =A0 =A0 =A0file->private_data =3D newdev; > > + =A0 =A0 =A0 error =3D nonseekable_open(inode, file); > + =A0 =A0 =A0 if (error) { > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 kfree(newdev); > + =A0 =A0 =A0 =A0 =A0 =A0 =A0 return error; > + =A0 =A0 =A0 } > + > =A0 =A0 =A0 =A0return 0; > =A0} > > Hmnn, if you look at nonseekable_open() it will always return 0. I think you can just do the following. diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c index 18206e1..697c0a6 100644 --- a/drivers/input/misc/uinput.c +++ b/drivers/input/misc/uinput.c @@ -291,7 +291,7 @@ static int uinput_open(struct inode *inode, struct = file *fil file->private_data =3D newdev; - return 0; + return nonseekable_open(inode, file); } Signed-off-by: John Kacur -- To unsubscribe from this list: send the line "unsubscribe linux-input" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html