[PATCH v2] [media] media-entity: don't sleep at media_device_register_entity()

[Mauro Carvalho Chehab <mchehab@osg.samsung.com>]

media_device_register_entity() is protected by a spin_lock.

Calling ida_pre_get() with GFP_KERNEL may put it to sleep,
with is a bad idea and causes this warning:

[ 8812.397195] BUG: sleeping function called from invalid context at mm/slub.c:1287
[ 8812.397203] in_atomic(): 1, irqs_disabled(): 0, pid: 15179, name: modprobe
[ 8812.397207] INFO: lockdep is turned off.
[ 8812.397213] CPU: 2 PID: 15179 Comm: modprobe Tainted: G    B           4.4.0-rc2+ #41
[ 8812.397218] Hardware name:                  /NUC5i7RYB, BIOS RYBDWi35.86A.0350.2015.0812.1722 08/12/2015
[ 8812.397222]  0000000000000000 ffff880314c77268 ffffffff818f8ba7 ffff8803b17dde00
[ 8812.397232]  ffff880314c77290 ffffffff811c2ee5 ffff8803b17dde00 ffffffff8284dbc9
[ 8812.397241]  0000000000000507 ffff880314c772d0 ffffffff811c30d5 0000000041b58ab3
[ 8812.397250] Call Trace:
[ 8812.397258]  [<ffffffff818f8ba7>] dump_stack+0x4b/0x64
[ 8812.397265]  [<ffffffff811c2ee5>] ___might_sleep+0x245/0x3a0
[ 8812.397270]  [<ffffffff811c30d5>] __might_sleep+0x95/0x1a0
[ 8812.397276]  [<ffffffff818fd083>] ? ida_pre_get+0x113/0x250
[ 8812.397282]  [<ffffffff8153bb77>] kmem_cache_alloc+0x197/0x250
[ 8812.397288]  [<ffffffff818fd083>] ida_pre_get+0x113/0x250
[ 8812.397293]  [<ffffffff818fd265>] ida_simple_get+0xa5/0x170
[ 8812.397298]  [<ffffffff818fd1c0>] ? ida_pre_get+0x250/0x250
[ 8812.397306]  [<ffffffffa07382d1>] media_device_register_entity+0x171/0x420 [media]
[ 8812.397318]  [<ffffffffa129e76f>] v4l2_device_register_subdev+0x34f/0x640 [videodev]
[ 8812.397324]  [<ffffffffa0768dea>] v4l2_i2c_new_subdev_board+0x12a/0x250 [v4l2_common]
[ 8812.397330]  [<ffffffffa0768fe7>] v4l2_i2c_new_subdev+0xd7/0x110 [v4l2_common]
[ 8812.397337]  [<ffffffffa0768f10>] ? v4l2_i2c_new_subdev_board+0x250/0x250 [v4l2_common]
[ 8812.397347]  [<ffffffffa13d2f76>] au0828_card_analog_fe_setup+0x2e6/0x3f0 [au0828]
[ 8812.397352]  [<ffffffff814450cc>] ? power_down+0xc4/0xc4
[ 8812.397361]  [<ffffffffa13d2c90>] ? au0828_tuner_callback+0x160/0x160 [au0828]
[ 8812.397370]  [<ffffffffa13d319f>] au0828_card_setup+0x11f/0x340 [au0828]
[ 8812.397378]  [<ffffffffa13d3080>] ? au0828_card_analog_fe_setup+0x3f0/0x3f0 [au0828]
[ 8812.397384]  [<ffffffff812a575b>] ? msleep+0x7b/0xc0
[ 8812.397393]  [<ffffffffa13d0d79>] au0828_usb_probe+0x679/0xcf0 [au0828]
[ 8812.397399]  [<ffffffff81d7619d>] usb_probe_interface+0x45d/0x940
[ 8812.397406]  [<ffffffff81ca7004>] driver_probe_device+0x454/0xd90
[ 8812.397411]  [<ffffffff81ca7940>] ? driver_probe_device+0xd90/0xd90
[ 8812.397417]  [<ffffffff81ca7940>] ? driver_probe_device+0xd90/0xd90
[ 8812.397422]  [<ffffffff81ca7a61>] __driver_attach+0x121/0x160
[ 8812.397427]  [<ffffffff81ca141f>] bus_for_each_dev+0x11f/0x1a0
[ 8812.397433]  [<ffffffff81ca1300>] ? subsys_dev_iter_exit+0x10/0x10
[ 8812.397439]  [<ffffffff822917d7>] ? _raw_spin_unlock+0x27/0x40
[ 8812.397445]  [<ffffffff81ca5d4d>] driver_attach+0x3d/0x50
[ 8812.397450]  [<ffffffff81ca5039>] bus_add_driver+0x4c9/0x770
[ 8812.397456]  [<ffffffff81ca944c>] driver_register+0x18c/0x3b0
[ 8812.397462]  [<ffffffff8124c952>] ? __raw_spin_lock_init+0x32/0x100
[ 8812.397468]  [<ffffffff81d71e58>] usb_register_driver+0x1f8/0x440
[ 8812.397473]  [<ffffffffa0208000>] ? 0xffffffffa0208000
[ 8812.397481]  [<ffffffffa02080b7>] au0828_init+0xb7/0x1000 [au0828]
[ 8812.397486]  [<ffffffff810021b1>] do_one_initcall+0x141/0x300
[ 8812.397492]  [<ffffffff81002070>] ? try_to_run_init_process+0x40/0x40
[ 8812.397497]  [<ffffffff8123bbf6>] ? trace_hardirqs_on_caller+0x16/0x590
[ 8812.397502]  [<ffffffff815406e6>] ? kasan_unpoison_shadow+0x36/0x50
[ 8812.397507]  [<ffffffff815406e6>] ? kasan_unpoison_shadow+0x36/0x50
[ 8812.397512]  [<ffffffff815406e6>] ? kasan_unpoison_shadow+0x36/0x50
[ 8812.397517]  [<ffffffff815407f7>] ? __asan_register_globals+0x87/0xa0
[ 8812.397524]  [<ffffffff814454e5>] do_init_module+0x1d0/0x5a4
[ 8812.397530]  [<ffffffff812ed7e8>] load_module+0x6648/0x9d70
[ 8812.397535]  [<ffffffff812e4b70>] ? symbol_put_addr+0x50/0x50
[ 8812.397546]  [<ffffffff812e71a0>] ? module_frob_arch_sections+0x20/0x20
[ 8812.397552]  [<ffffffff8158e950>] ? open_exec+0x50/0x50
[ 8812.397559]  [<ffffffff811648db>] ? ns_capable+0x5b/0xd0
[ 8812.397565]  [<ffffffff812f1208>] SyS_finit_module+0x108/0x130
[ 8812.397571]  [<ffffffff812f1100>] ? SyS_init_module+0x1f0/0x1f0
[ 8812.397576]  [<ffffffff81004044>] ? lockdep_sys_exit_thunk+0x12/0x14
[ 8812.397582]  [<ffffffff82292236>] entry_SYSCALL_64_fastpath+0x16/0x7a

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
---
 drivers/media/media-device.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/media/media-device.c b/drivers/media/media-device.c
index 3e0227555196..b786b1092044 100644
--- a/drivers/media/media-device.c
+++ b/drivers/media/media-device.c
@@ -537,6 +537,7 @@ int __must_check media_device_register_entity(struct media_device *mdev,
 					      struct media_entity *entity)
 {
 	unsigned int i;
+	int ret;
 
 	if (entity->function == MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN ||
 	    entity->function == MEDIA_ENT_F_UNKNOWN)
@@ -551,13 +552,16 @@ int __must_check media_device_register_entity(struct media_device *mdev,
 	entity->num_links = 0;
 	entity->num_backlinks = 0;
 
+	if (!ida_pre_get(&mdev->entity_internal_idx, GFP_KERNEL))
+		return -ENOMEM;
+
 	spin_lock(&mdev->lock);
 
-	entity->internal_idx = ida_simple_get(&mdev->entity_internal_idx, 1, 0,
-					      GFP_KERNEL);
-	if (entity->internal_idx < 0) {
+	ret = ida_get_new_above(&mdev->entity_internal_idx, 1,
+				&entity->internal_idx);
+	if (ret < 0) {
 		spin_unlock(&mdev->lock);
-		return entity->internal_idx;
+		return ret;
 	}
 
 	mdev->entity_internal_idx_max =
-- 
2.5.0