UPSTREAM: regmap: fix deadlock on _regmap_raw_write() error path

Commit 815806e39bf6 ("regmap: drop cache if the bus transfer error")
added a call to regcache_drop_region() to error path in
_regmap_raw_write(). However that path runs with regmap lock taken,
and regcache_drop_region() tries to re-take it, causing a deadlock.
Fix that by calling map->cache_ops->drop() directly.

Change-Id: I55c6d3ed490c47e8b3f5ca774d051a700f707b6e
Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Huang, Tao <huangtao@rock-chips.com>
(cherry picked from git.kernel.org broonie/regmap.git for-next
 commit f0aa1ce6259eb65f53f969b3250c1d0aac84f30b)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index bb216c9d3c0904143a0dbb1960a735646de57201..d94831a45b74f2f23a62998194d660c0780fbbb3 100644 (file)
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1373,7 +1373,11 @@ int _regmap_raw_write(struct regmap *map, unsigned int reg,
 
                kfree(buf);
        } else if (ret != 0 && !map->cache_bypass && map->format.parse_val) {
-               regcache_drop_region(map, reg, reg + 1);
+               /* regcache_drop_region() takes lock that we already have,
+                * thus call map->cache_ops->drop() directly
+                */
+               if (map->cache_ops && map->cache_ops->drop)
+                       map->cache_ops->drop(map, reg, reg + 1);
        }
 
        trace_regmap_hw_write_done(map, reg, val_len / map->format.val_bytes);