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From: John Stultz <john.stultz@linaro.org>
Date: Mon, 24 Jul 2017 14:00:45 -0700
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Subject: Re: [PATCH 02/37] binder: use group leader instead of open thread
To: Todd Kjos <tkjos@android.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
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        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Martijn Coenen <maco@google.com>, Todd Kjos <tkjos@google.com>
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On Thu, Jun 29, 2017 at 12:01 PM, Todd Kjos <tkjos@android.com> wrote:
> The binder allocator assumes that the thread that
> called binder_open will never die for the lifetime of
> that proc. That thread is normally the group_leader,
> however it may not be. Use the group_leader instead
> of current.
>
> Signed-off-by: Todd Kjos <tkjos@google.com>
> ---
>  drivers/android/binder.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 157bd3e49ff4..9393924ae8e8 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -3460,8 +3460,8 @@ static int binder_open(struct inode *nodp, struct file *filp)
>         proc = kzalloc(sizeof(*proc), GFP_KERNEL);
>         if (proc == NULL)
>                 return -ENOMEM;
> -       get_task_struct(current);
> -       proc->tsk = current;
> +       get_task_struct(current->group_leader);
> +       proc->tsk = current->group_leader;
>         INIT_LIST_HEAD(&proc->todo);
>         init_waitqueue_head(&proc->wait);
>         proc->default_priority = task_nice(current);
> --

So this patch landed in 4.13-rc2 (c4ea41ba195d), and seems to be
causing a regression for me w/ HiKey. With it, I'm getting crashes
with the bluetooth and wifi HALs.  Reverting this patch seems to
resolve the issue

I suspect some other dependency from the original patchset is missing?

thanks
-john