From: Cristian Ciocaltea cristian.ciocaltea@collabora.com
[ Upstream commit 1ed9b927e7dd8b8cff13052efe212a8ff72ec51d ]
In some cases when using the maple tree register cache, the lockdep validator might complain about invalid deadlocks:
[7.131886] Possible interrupt unsafe locking scenario:
[7.131890] CPU0 CPU1 [7.131893] ---- ---- [7.131896] lock(&mt->ma_lock); [7.131904] local_irq_disable(); [7.131907] lock(rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock); [7.131916] lock(&mt->ma_lock); [7.131925] <Interrupt> [7.131928] lock(rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock); [7.131936] *** DEADLOCK ***
[7.131939] no locks held by swapper/0/0. [7.131944] the shortest dependencies between 2nd lock and 1st lock: [7.131950] -> (&mt->ma_lock){+.+.}-{2:2} { [7.131966] HARDIRQ-ON-W at: [7.131973] lock_acquire+0x200/0x330 [7.131986] _raw_spin_lock+0x50/0x70 [7.131998] regcache_maple_write+0x68/0xe0 [7.132010] regcache_write+0x6c/0x90 [7.132019] _regmap_read+0x19c/0x1d0 [7.132029] _regmap_update_bits+0xc0/0x148 [7.132038] regmap_update_bits_base+0x6c/0xa8 [7.132048] rk8xx_probe+0x22c/0x3d8 [7.132057] rk8xx_spi_probe+0x74/0x88 [7.132065] spi_probe+0xa8/0xe0
[...]
[7.132675] } [7.132678] ... key at: [<ffff800082943c20>] __key.0+0x0/0x10 [7.132691] ... acquired at: [7.132695] _raw_spin_lock+0x50/0x70 [7.132704] regcache_maple_write+0x68/0xe0 [7.132714] regcache_write+0x6c/0x90 [7.132724] _regmap_read+0x19c/0x1d0 [7.132732] _regmap_update_bits+0xc0/0x148 [7.132741] regmap_field_update_bits_base+0x74/0xb8 [7.132751] vop2_plane_atomic_update+0x480/0x14d8 [rockchipdrm] [7.132820] drm_atomic_helper_commit_planes+0x1a0/0x320 [drm_kms_helper]
[...]
[7.135112] -> (rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock){-...}-{2:2} { [7.135130] IN-HARDIRQ-W at: [7.135136] lock_acquire+0x200/0x330 [7.135147] _raw_spin_lock_irqsave+0x6c/0x98 [7.135157] regmap_lock_spinlock+0x20/0x40 [7.135166] regmap_read+0x44/0x90 [7.135175] vop2_isr+0x90/0x290 [rockchipdrm] [7.135225] __handle_irq_event_percpu+0x124/0x2d0
In the example above, the validator seems to get the scope of dependencies wrong, since the regmap instance used in rk8xx-spi driver has nothing to do with the instance from vop2.
Improve validation by sharing the regmap's lockdep class with the maple tree's internal lock, while also providing a subclass for the latter.
Signed-off-by: Cristian Ciocaltea cristian.ciocaltea@collabora.com Link: https://patch.msgid.link/20241031-regmap-maple-lockdep-fix-v2-1-06a3710f3623... Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/base/regmap/internal.h | 1 + drivers/base/regmap/regcache-maple.c | 3 +++ drivers/base/regmap/regmap.c | 1 + 3 files changed, 5 insertions(+)
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h index 83acccdc10089..bdb450436cbc5 100644 --- a/drivers/base/regmap/internal.h +++ b/drivers/base/regmap/internal.h @@ -59,6 +59,7 @@ struct regmap { unsigned long raw_spinlock_flags; }; }; + struct lock_class_key *lock_key; regmap_lock lock; regmap_unlock unlock; void *lock_arg; /* This is passed to lock/unlock functions */ diff --git a/drivers/base/regmap/regcache-maple.c b/drivers/base/regmap/regcache-maple.c index 2dea9d259c493..e98c05f9d216f 100644 --- a/drivers/base/regmap/regcache-maple.c +++ b/drivers/base/regmap/regcache-maple.c @@ -355,6 +355,9 @@ static int regcache_maple_init(struct regmap *map)
mt_init(mt);
+ if (!mt_external_lock(mt) && map->lock_key) + lockdep_set_class_and_subclass(&mt->ma_lock, map->lock_key, 1); + if (!map->num_reg_defaults) return 0;
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c index bfc6bc1eb3a4a..b60a6036c2cd1 100644 --- a/drivers/base/regmap/regmap.c +++ b/drivers/base/regmap/regmap.c @@ -745,6 +745,7 @@ struct regmap *__regmap_init(struct device *dev, lock_key, lock_name); } map->lock_arg = map; + map->lock_key = lock_key; }
/*