Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756144Ab0BAU1s (ORCPT ); Mon, 1 Feb 2010 15:27:48 -0500 Received: from mail-ew0-f228.google.com ([209.85.219.228]:65243 "EHLO mail-ew0-f228.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754821Ab0BAU1r convert rfc822-to-8bit (ORCPT ); Mon, 1 Feb 2010 15:27:47 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=JNfdVpTPVJNCI7r2I/aMhavclLsG/qDrxQ5DOk5anCBMLLT9OrCpKqXIFpZOva4wYw S4Vz5tRPZaOkFallzkFO5lV8qO+OYUMzDXuEPwZSWcyihvxc78lNuN612BLhOWZ5MTm4 iJbzkVatE6uf8xhGS2wJJJrYrDBzSYS8cRDAQ= MIME-Version: 1.0 In-Reply-To: <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> <520f0cf11002011222h134dbf06rf1db612da9a9728@mail.gmail.com> Date: Mon, 1 Feb 2010 21:27:22 +0100 Message-ID: <520f0cf11002011227s74e57673j3922941f7ee87989@mail.gmail.com> Subject: Re: [PATCH] input: remove BKL from uinput open function From: John Kacur To: Dmitry Torokhov Cc: Arnd Bergmann , Thadeu Lima de Souza Cascardo , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3415 Lines: 95 On Mon, Feb 1, 2010 at 9:22 PM, John Kacur wrote: > 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? >>> > ?.llseek ? ? ? ? = no_llseek, >>> >>> That's one of the possible solutions. Assigning it to generic_file_llseek >>> also gets rid of the BKL but keeps the current behaviour (calling seek >>> 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 >> --- >> >> ?drivers/input/misc/uinput.c | ? ?7 +++++++ >> ?1 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_device *udev) >> ?static int uinput_open(struct inode *inode, struct file *file) >> ?{ >> ? ? ? ?struct uinput_device *newdev; >> + ? ? ? int error; >> >> ? ? ? ?newdev = kzalloc(sizeof(struct uinput_device), GFP_KERNEL); >> ? ? ? ?if (!newdev) >> @@ -291,6 +292,12 @@ static int uinput_open(struct inode *inode, struct file *file) >> >> ? ? ? ?file->private_data = newdev; >> >> + ? ? ? error = nonseekable_open(inode, file); >> + ? ? ? if (error) { >> + ? ? ? ? ? ? ? kfree(newdev); >> + ? ? ? ? ? ? ? return error; >> + ? ? ? } >> + >> ? ? ? ?return 0; >> ?} >> >> > > 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 = newdev; > > - ? ? ? return 0; > + ? ? ? return nonseekable_open(inode, file); > ?} > > Signed-off-by: John Kacur > Btw, Thadeu Lima de Souza Cascardo should just combine that all into one patch, no point really in making two patches out of that. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/