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regmap: maple: Drop the RCU read lock while syncing registers

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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 <pierre-louis.bossart@linux.intel.com>
Tested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230523-regcache-maple-sync-lock-v1-1-530e4d68dfab@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Mark Brown 2023-05-23 23:18:19 +01:00
parent 95856d1f3c
commit 0cc6578048
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 4 additions and 1 deletions
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5
drivers/base/regmap/regcache-maple.c
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@ -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;