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From:   Yunhan Wang <yunhanw@google.com>
Date:   Thu, 25 Oct 2018 10:49:22 -0700
Message-ID: <CALvjcs_-_DuXJWt8zWj4wH32Dz2w41UdPKxfOqQ5ZwA-gqO1mw@mail.gmail.com>
Subject: Re: [PATCH] gatt: Fix double att_disconnected issue on disconnection
To:     Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc:     linux-bluetooth@vger.kernel.org
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi, Luiz

Just have a test with your patch in master branch, both crashes are
still there, and att_disconnected has been called for two times even
though unregistering the handler....

Thanks
Best wishes
Yunhan

Program received signal SIGSEGV, Segmentation fault.
btd_adapter_find_device (adapter=3D0x72657664612f6372,
dst=3Ddst@entry=3D0x555555872998, bdaddr_type=3D0 '\000')
    at bluez/repo/src/adapter.c:845
845 list =3D g_slist_find_custom(adapter->devices, &addr,
(gdb) bt
#0  btd_adapter_find_device (adapter=3D0x72657664612f6372,
dst=3Ddst@entry=3D0x555555872998, bdaddr_type=3D0 '\000')
    at bluez/repo/src/adapter.c:845
#1  0x00005555555ab890 in att_disconnected (err=3D<optimized out>,
user_data=3D0x555555872990)
    at bluez/repo/src/gatt-database.c:329
#2  0x00005555555eaba8 in queue_foreach (queue=3D0x55555585de60,
function=3Dfunction@entry=3D0x5555555ee5f0 <disconn_handler>,
user_data=3D0x68)
    at bluez/repo/src/shared/queue.c:220
#3  0x00005555555ef819 in disconnect_cb (io=3D<optimized out>,
user_data=3D0x555555869d50)
    at bluez/repo/src/shared/att.c:592
#4  0x00005555555f89a3 in watch_callback (channel=3D<optimized out>,
cond=3D<optimized out>, user_data=3D<optimized out>)
    at bluez/repo/src/shared/io-glib.c:170
#5  0x00007ffff7b0fe35 in g_main_context_dispatch () from
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#6  0x00007ffff7b10200 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#7  0x00007ffff7b10512 in g_main_loop_run () from
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#8  0x0000555555572238 in main (argc=3D<optimized out>, argv=3D<optimized
out>) at bluez/repo/src/main.c:808


Program received signal SIGSEGV, Segmentation fault.
queue_remove (queue=3D0x30, data=3Ddata@entry=3D0x555555873740) at
bluez/repo/src/shared/queue.c:256
256 for (entry =3D queue->head, prev =3D NULL; entry;
(gdb) bt
#0  queue_remove (queue=3D0x30, data=3Ddata@entry=3D0x555555873740) at
bluez/repo/src/shared/queue.c:256
#1  0x00005555555ab8c5 in att_disconnected (err=3D<optimized out>,
user_data=3D0x555555873740)
    at bluez/repo/src/gatt-database.c:350
#2  0x00005555555eabb8 in queue_foreach (queue=3D0x55555586e670,
function=3Dfunction@entry=3D0x5555555ee600 <disconn_handler>,
user_data=3D0x68)
    at bluez/repo/src/shared/queue.c:220
#3  0x00005555555ef829 in disconnect_cb (io=3D<optimized out>,
user_data=3D0x555555865f50)
    at bluez/repo/src/shared/att.c:592
#4  0x00005555555f89b3 in watch_callback (channel=3D<optimized out>,
cond=3D<optimized out>, user_data=3D<optimized out>)
    at bluez/repo/src/shared/io-glib.c:170
#5  0x00007ffff7b0fe35 in g_main_context_dispatch () from
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#6  0x00007ffff7b10200 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#7  0x00007ffff7b10512 in g_main_loop_run () from
/lib/x86_64-linux-gnu/libglib-2.0.so.0
#8  0x0000555555572238 in main (argc=3D<optimized out>, argv=3D<optimized
out>) at  bluez/repo/src/main.c:808
On Thu, Oct 25, 2018 at 2:20 AM Luiz Augusto von Dentz
<luiz.dentz@gmail.com> wrote:
>
> Hi Yunhan,
>
> On Thu, Oct 25, 2018 at 4:47 AM Yunhan Wang <yunhanw@google.com> wrote:
> >
> > Hi, Luiz
> >
> > I am observing the multiple crashes when doing BLE disconnection using
> > latest bluez master..It looks like the two att_disconnect are
> > triggered from your last gatt commit.. Please help take a look at this
> > workaround and comments.. the better solution might be to figure out
> > how to handle the disconnection along with random address and public
> > address together regarding the previous issue, Gatt: Subscriptions are
> > not cleared after disconnection from a temporary device
>
> Ive pushed a similar fix, it should remove the handler before calling
> att_disconnected.
>
> > Thanks
> > Best wishes
> > Yunhan
> > On Wed, Oct 24, 2018 at 5:42 PM yunhanw <yunhanw@google.com> wrote:
> > >
> > > When BLE disconnection happens, att_disconnect is triggered from two =
locations, the new added location is gatt_server_cleanup, it would cause se=
veral blueetoothd crashes. This bus is introduced from commit 634f0a6e1125a=
f8d5959bff119d9336a8d81c028, where gatt fix, gatt subscriptions are not cle=
ared after disconnection from a temporary device with private/random addres=
s. In order to workaround this issue, btd_gatt_database_att_disconnected ca=
n only be triggered when address type is random, and for others, it can con=
tinue to use original disconnect code path.
> > >
> > >     crash 1
> > >     Program received signal SIGSEGV, Segmentation fault.
> > >     queue_remove (queue=3D0x30, data=3Ddata@entry=3D0x555555872a40) a=
t /repo/src/shared/queue.c:256
> > >     256     for (entry =3D queue->head, prev =3D NULL; entry;
> > >     (gdb) backtrace
> > >         at /bluez/repo/src/gatt-database.c:350
> > >         at bluez/repo/src/shared/queue.c:220
> > >         at bluez/repo/src/shared/att.c:592
> > >         at bluez/repo/src/shared/io-glib.c:170
> > >
> > >     crash 2
> > >         at bluez/repo/src/shared/queue.c:220
> > >         at bluez/repo/src/shared/att.c:592
> > >         at bluez/repo/src/shared/io-glib.c:170
> > >
> > >     (gdb) print state->db->adapter
> > >     Cannot access memory at address 0x61672f6269727474
> > > ---
> > >  src/gatt-database.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/src/gatt-database.c b/src/gatt-database.c
> > > index 783b692d5..2f0eb83b5 100644
> > > --- a/src/gatt-database.c
> > > +++ b/src/gatt-database.c
> > > @@ -3365,6 +3365,8 @@ void btd_gatt_database_att_disconnected(struct =
btd_gatt_database *database,
> > >
> > >         addr =3D device_get_address(device);
> > >         type =3D btd_device_get_bdaddr_type(device);
> > > +    if (type !=3D BDADDR_LE_RANDOM)
> > > +        return;
> > >
> > >         state =3D find_device_state(database, addr, type);
> > >         if (!state)
> > > --
> > > 2.19.1.568.g152ad8e336-goog
> > >
>
>
>
> --
> Luiz Augusto von Dentz