lkml.org 
[lkml]   [2017]   [Jul]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] binder: Drop needless locking in binder_mmap()
On Mon, Jun 19, 2017 at 05:53:34PM +0300, Dmitry Safonov wrote:
> On 05/24/2017 05:51 PM, Dmitry Safonov wrote:
> > binder_mmap() protected proc->buffer from concurrent changes.
> > It was introduced with commit bd1eff9741af ("Staging: android: binder:
> > Fix crashes when sharing a binder file between processes").
> >
> > The commit fixed such races alike:
> >
> > task1
> > =====
> > fd = open("/dev/binder",..)
> > fork()
> > ---------------------------------------->task2
> > | =====
> > mmap(fd) mmap(fd)
> >
> > Afterwards the situation was changed with the commit a79f41ed9786
> > ("binder: don't allow mmap() by process other than proc->tsk").
> > That commit prohibited mmap'ing of fd, that was opened by some
> > other task.
> > That restriction has made locking in binder_mmap() unnecessary.
> >
> > Cc: Al Viro <viro@zeniv.linux.org.uk>
> > Cc: "Arve Hjønnevåg" <arve@android.com>
> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Cc: Riley Andrews <riandrews@android.com>
> > Cc: devel@driverdev.osuosl.org
> > Cc: Android Kernel Team <kernel-team@android.com>
> > Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
> > ---
> > drivers/android/binder.c | 5 -----
> > 1 file changed, 5 deletions(-)
>
> Ping?

The "break up the binder lock" patches should have now made this
obsolete, right? If not, can you please rebase it on my
char-misc-testing tree and resend?

thanks,

greg k-h

\
 
 \ /
  Last update: 2017-07-17 14:52    [W:0.050 / U:4.008 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site