From: Mark Brown Date: Tue, 23 May 2023 22:18:19 +0000 (+0100) Subject: regmap: maple: Drop the RCU read lock while syncing registers X-Git-Tag: v6.6.7~2651^2~2 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0cc6578048e0980d254aee345130cced4912f723;p=platform%2Fkernel%2Flinux-starfive.git regmap: maple: Drop the RCU read lock while syncing registers Unfortunately the maple tree requires us to explicitly lock it so we need to take the RCU read lock while iterating. When syncing this means that we end up trying to write out register values while holding the RCU read lock which triggers lockdep issues since that is an atomic context but most buses can't be used in atomic context. Pause the iteration and drop the lock for each register we check to avoid this. Reported-by: Pierre-Louis Bossart Tested-by: Pierre-Louis Bossart Signed-off-by: Mark Brown Link: https://lore.kernel.org/r/20230523-regcache-maple-sync-lock-v1-1-530e4d68dfab@kernel.org Signed-off-by: Mark Brown --- diff --git a/drivers/base/regmap/regcache-maple.c b/drivers/base/regmap/regcache-maple.c index 9b1b559..c2e3a0f 100644 --- a/drivers/base/regmap/regcache-maple.c +++ b/drivers/base/regmap/regcache-maple.c @@ -203,15 +203,18 @@ static int regcache_maple_sync(struct regmap *map, unsigned int min, mas_for_each(&mas, entry, max) { for (r = max(mas.index, lmin); r <= min(mas.last, lmax); r++) { + mas_pause(&mas); + rcu_read_unlock(); ret = regcache_sync_val(map, r, entry[r - mas.index]); if (ret != 0) goto out; + rcu_read_lock(); } } -out: rcu_read_unlock(); +out: map->cache_bypass = false; return ret;