random: Forbid llseek on random chardev
in [Kernel]
|
From: Matt Mackall on 10 Apr 2010 12:30 On Sat, 2010-04-10 at 16:17 +0200, Frederic Weisbecker wrote: > From: Arnd Bergmann <arnd(a)arndb.de> > > Seeking on /dev/random and /dev/urandom is pointless. It is indeed pointless, though that doesn't mean no one does it. Forbidding a no-op seems a rather unfriendly way to fix this. > Using generic_file_llseek means we no longer need to > take the BKL if anyone tries to seek on these. Comment doesn't match the patch? > Signed-off-by: Arnd Bergmann <arnd(a)arndb.de> > Cc: Matt Mackall <mpm(a)selenic.com> > Cc: Andrew Morton <akpm(a)linux-foundation.org> > Signed-off-by: Frederic Weisbecker <fweisbec(a)gmail.com> > --- > drivers/char/random.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/drivers/char/random.c b/drivers/char/random.c > index 2fd3d39..513c685 100644 > --- a/drivers/char/random.c > +++ b/drivers/char/random.c > @@ -1169,6 +1169,7 @@ const struct file_operations random_fops = { > .poll = random_poll, > .unlocked_ioctl = random_ioctl, > .fasync = random_fasync, > + .open = nonseekable_open, > }; > > const struct file_operations urandom_fops = { > @@ -1176,6 +1177,7 @@ const struct file_operations urandom_fops = { > .write = random_write, > .unlocked_ioctl = random_ioctl, > .fasync = random_fasync, > + .open = nonseekable_open, > }; > > /*************************************************************** -- http://selenic.com : development and support for Mercurial and Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Frederic Weisbecker on 10 Apr 2010 12:40 On Sat, Apr 10, 2010 at 11:25:50AM -0500, Matt Mackall wrote: > On Sat, 2010-04-10 at 16:17 +0200, Frederic Weisbecker wrote: > > From: Arnd Bergmann <arnd(a)arndb.de> > > > > Seeking on /dev/random and /dev/urandom is pointless. > > It is indeed pointless, though that doesn't mean no one does it. > Forbidding a no-op seems a rather unfriendly way to fix this. I worried about that too. If you think that could break some user space apps, we can make it a generic_file_llseek. > > Using generic_file_llseek means we no longer need to > > take the BKL if anyone tries to seek on these. > > Comment doesn't match the patch? Oops. I guess the patch has been updated, but not the changelog. Some background: we are trying to remove the uses of default_llseek that use the bkl. We started with turning llseek stubs to generic_file_llseek (or non seekable open in some cases), but we are hesitating now and think about actually turn all the stubs that might need the bkl into default_llseek, and fallback to generic_file_llseek for all other stubs. Depending on what we do I'll resend you an updated version of this patch with generic_file_llseek, or I will let the stub as is. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Matt Mackall on 10 Apr 2010 13:10 On Sat, 2010-04-10 at 18:35 +0200, Frederic Weisbecker wrote: > On Sat, Apr 10, 2010 at 11:25:50AM -0500, Matt Mackall wrote: > > On Sat, 2010-04-10 at 16:17 +0200, Frederic Weisbecker wrote: > > > From: Arnd Bergmann <arnd(a)arndb.de> > > > > > > Seeking on /dev/random and /dev/urandom is pointless. > > > > It is indeed pointless, though that doesn't mean no one does it. > > Forbidding a no-op seems a rather unfriendly way to fix this. > > > I worried about that too. If you think that could break some user > space apps, we can make it a generic_file_llseek. > > > > > Using generic_file_llseek means we no longer need to > > > take the BKL if anyone tries to seek on these. > > > > Comment doesn't match the patch? > > > Oops. I guess the patch has been updated, but not the changelog. > > Some background: we are trying to remove the uses of default_llseek > that use the bkl. We started with turning llseek stubs to > generic_file_llseek (or non seekable open in some cases), but we are > hesitating now and think about actually turn all the stubs that > might need the bkl into default_llseek, and fallback to > generic_file_llseek for all other stubs. > > Depending on what we do I'll resend you an updated version > of this patch with generic_file_llseek, or I will let the stub > as is. Sounds good. -- http://selenic.com : development and support for Mercurial and Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Arnd Bergmann on 10 Apr 2010 14:00 On Saturday 10 April 2010 18:35:30 Frederic Weisbecker wrote: > > > > Using generic_file_llseek means we no longer need to > > > take the BKL if anyone tries to seek on these. > > > > Comment doesn't match the patch? Yes, my fault. The version in my series already had this problem. > Oops. I guess the patch has been updated, but not the changelog. > > Some background: we are trying to remove the uses of default_llseek > that use the bkl. We started with turning llseek stubs to > generic_file_llseek (or non seekable open in some cases), but we are > hesitating now and think about actually turn all the stubs that > might need the bkl into default_llseek, and fallback to > generic_file_llseek for all other stubs. > > Depending on what we do I'll resend you an updated version > of this patch with generic_file_llseek, or I will let the stub > as is. The noop_llseek from Jan's series seems most appropriate here. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|
Pages: 1 Prev: [PATCH] dm: Use nonseekable_open Next: [PATCHv2] MTD: Suppress warnings in inline_map_read() |