Applied "regmap: fix deadlock on _regmap_raw_write() error path" to the regmap tree

[Mark Brown <broonie@kernel.org>]

The patch

   regmap: fix deadlock on _regmap_raw_write() error path

has been applied to the regmap tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

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Thanks,
Mark

>From f0aa1ce6259eb65f53f969b3250c1d0aac84f30b Mon Sep 17 00:00:00 2001
From: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Date: Thu, 22 Sep 2016 12:02:25 +0300
Subject: [PATCH] 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>
---
 drivers/base/regmap/regmap.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 25d26bb18970..e964d068874d 100644
--- 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);
-- 
2.8.1