Messages in this thread | | | Date | Mon, 17 Jul 2017 14:52:19 +0200 | From | Greg Kroah-Hartman <> | Subject | Re: [PATCH] binder: Drop needless locking in binder_mmap() |
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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
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