lkml.org 
[lkml]   [2010]   [Mar]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [GIT, RFC] Killing the Big Kernel Lock
Date
On Monday 29 March 2010, Frederic Weisbecker wrote:
> On Mon, Mar 29, 2010 at 01:18:48AM +0200, Frederic Weisbecker wrote:
> > @@ -1943,7 +1949,7 @@ static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,
> > }
> >
> > static const struct file_operations proc_fdinfo_file_operations = {
> > - .open = nonseekable_open,
> > + .llseek = generic_file_llseek,
> > .read = proc_fdinfo_read,
> > };
> >
> >
> > Replacing default_llseek() by generic_file_llseek() as you
> > did for most of the other parts is fine.
> >
> > But the above changes the semantics as it makes it seekable.
> > Why not just keeping it as is? It just ends up in no_llseek().

The default is default_llseek, which uses the BKL and cannot be
used if procfs is builtin and the BKL is a module.

> There is also the ioctl part that takes the bkl in procfs.
> I'll just check nothing weird happens there wrt file pos.
> We probably first need to pushdown the bkl in the procfs
> ioctl handlers.

The BKL in procfs is only for proc files that have registered
their own .ioctl instead of .unlocked_ioctl method. Converting
every file_operations instance to provide an unlocked_ioctl
(as one of the other patches does) makes sure that this path
is never taken. BTW, there are less than a handful of procfs files
that provide an ioctl operation, and those probably should never
have been merged.

Arnd


\
 
 \ /
  Last update: 2010-03-29 13:07    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site