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.

Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 25d26bb..e964d06 100644 (file)
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1475,7 +1475,11 @@ 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);