diff options
| author | Marius Vlad | 2017-12-13 20:10:48 +0200 |
|---|---|---|
| committer | Daniel Vetter | 2017-12-14 08:25:37 +0100 |
| commit | bd36d3bab2e3d08f80766c86487090dbceed4651 (patch) | |
| tree | 314779fcae0a802ed45a968bd622693cfb0f010f /drivers/gpu | |
| parent | ea497bb92064875497554ee7cdf10df7fb7393fc (diff) | |
drm/drm_lease: Prevent deadlock in case drm_lease_create() fails
This case can been seen when creating the lease with the same objects passed.
[ 605.515097] 2 locks held by testapp/3337:
[ 605.519027] #0: (&dev->mode_config.idr_mutex){......}, at: [<ffff0000085f1664>] drm_mode_create_lease_ioctl+0x384/0x858
[ 605.530045] #1: (&dev->mode_config.idr_mutex){......}, at: [<ffff0000085f11bc>] drm_lease_destroy+0x2c/0x110
Which was causing the process to hang:
[ 605.398827] [<ffff0000080856cc>] __switch_to+0x94/0xa8
[ 605.404030] [<ffff000008c05d00>] __schedule+0x1b0/0x698
[ 605.409322] [<ffff000008c06224>] schedule+0x3c/0xa8
[ 605.414260] [<ffff000008c06628>] schedule_preempt_disabled+0x20/0x38
[ 605.420677] [<ffff000008c07370>] mutex_lock_nested+0x158/0x340
[ 605.426572] [<ffff0000085f11bc>] drm_lease_destroy+0x2c/0x110
[ 605.432389] [<ffff0000085cecf0>] drm_master_put+0xc0/0xc8
[ 605.437845] [<ffff0000085f175c>] drm_mode_create_lease_ioctl+0x47c/0x858
[ 605.444612] [<ffff0000085d4460>] drm_ioctl+0x198/0x448
[ 605.449811] [<ffff000008201134>] do_vfs_ioctl+0xa4/0x748
[ 605.455192] [<ffff000008201864>] SyS_ioctl+0x8c/0xa0
[ 605.460216] [<ffff000008082f4c>] __sys_trace_return+0x0/0x4
drm_mode_create_lease_ioctl() calls drm_lease_create() which acquires a lock
on dev->mode_config.idr_mutex. In case of failure, drm_lease_create() calls
drm_master_put() which in turn tries to acquire the same lock when calling
drm_lease_destroy().
v2: - Reverse the order at exit in case of fail, so that unlocking takes place
before dropping the reference.
- Include detail information about deadlock (Daniel Vetter)
Signed-off-by: Marius Vlad <marius-cristian.vlad@nxp.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171213181048.32719-1-marius-cristian.vlad@nxp.com
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/drm_lease.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_lease.c b/drivers/gpu/drm/drm_lease.c index d1eb56a1eff4..59849f02e2ad 100644 --- a/drivers/gpu/drm/drm_lease.c +++ b/drivers/gpu/drm/drm_lease.c @@ -254,10 +254,10 @@ static struct drm_master *drm_lease_create(struct drm_master *lessor, struct idr return lessee; out_lessee: - drm_master_put(&lessee); - mutex_unlock(&dev->mode_config.idr_mutex); + drm_master_put(&lessee); + return ERR_PTR(error); } |