[PATCH 02/37] binder: use group leader instead of open thread

[Martijn Coenen]

I took the time to look at what else is different between common and
upstream, and just sent 3 patches to LKML to reconcile. One of the 3
fixes this particular problem.

On Thu, Jul 27, 2017 at 3:42 PM, Amit Pundir <amit.pundir at linaro.org> wrote:
> On 27 July 2017 at 18:53, Greg Kroah-Hartman <gregkh at linuxfoundation.org> wrote:
>> On Thu, Jul 27, 2017 at 02:38:30PM +0530, Amit Pundir wrote:
>>> Hi,
>>>
>>> On 25 July 2017 at 14:43, Martijn Coenen <maco at google.com> wrote:
>>> > Hi John,
>>> >
>>> > On Mon, Jul 24, 2017 at 11:07 PM, John Stultz <john.stultz at linaro.org> wrote:
>>> >>
>>> >> 12-31 16:00:36.632  2518  2584 E hw-ProcessState: Using /dev/hwbinder
>>> >> failed: unable to mmap transaction memory.
>>> >
>>> > This doesn't look right. Is there anything in the kernel log?
>>>
>>> There is a slight difference in this patch and the one that got pushed
>>> in android-4.9[1]. I cherry-picked those changes and got BT/WiFi
>>> working again on Hikey with mainline tracking (4.13-rc2) tree.
>>>
>>> Regards,
>>> Amit Pundir
>>> [1] https://android.googlesource.com/kernel/common/+/872c26eb0776ef160447d8703779e2bce0b7230a%5E%21/#F0
>>
>> And what is that difference?
>
> These couple of lines of change:
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index f7665c31feca..d7291a5a13e1 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -3362,7 +3362,7 @@ static int binder_mmap(struct file *filp, struct
> vm_area_struct *vma)
>         const char *failure_string;
>         struct binder_buffer *buffer;
>
> -       if (proc->tsk != current)
> +       if (proc->tsk != current->group_leader)
>                 return -EINVAL;
>
>         if ((vma->vm_end - vma->vm_start) > SZ_4M)
> @@ -3466,6 +3466,7 @@ static int binder_open(struct inode *nodp,
> struct file *filp)
>                 return -ENOMEM;
>         get_task_struct(current->group_leader);
>         proc->tsk = current->group_leader;
> +       proc->vma_vm_mm = current->group_leader->mm;
>         INIT_LIST_HEAD(&proc->todo);
>         init_waitqueue_head(&proc->wait);
>         proc->default_priority = task_nice(current);
>
> John reported hw_binder mmap failure in his logcat. So I'm assuming
> that the check in binder_mmap is where the binder failed and returned.
>
> Regards,
> Amit Pundir