linux-kernel - Re: [PATCH 02/37] binder: use group leader instead of open thread

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Date:   Thu, 27 Jul 2017 19:12:35 +0530
From:   Amit Pundir <amit.pundir@...aro.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Martijn Coenen <maco@...gle.com>,
        John Stultz <john.stultz@...aro.org>,
        Todd Kjos <tkjos@...roid.com>,
        Arve Hjønnevåg <arve@...roid.com>,
        devel@...verdev.osuosl.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Todd Kjos <tkjos@...gle.com>
Subject: Re: [PATCH 02/37] binder: use group leader instead of open thread

On 27 July 2017 at 18:53, Greg Kroah-Hartman <gregkh@...uxfoundation.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@...gle.com> wrote:
>> > Hi John,
>> >
>> > On Mon, Jul 24, 2017 at 11:07 PM, John Stultz <john.stultz@...aro.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