linux-kernel - Applied "regmap: Disable debugfs when locking is disabled" to the regmap tree

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Date:   Wed, 13 Dec 2017 16:23:05 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Mark Brown <broonie@...nel.org>
Cc:     Lars-Peter Clausen <lars@...afoo.de>, linux-kernel@...r.kernel.org
Subject: Applied "regmap: Disable debugfs when locking is disabled" to the regmap tree

The patch

   regmap: Disable debugfs when locking is disabled

has been applied to the regmap tree at

   https://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.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 72465736adf2aade263a9475a1d42007fd49e703 Mon Sep 17 00:00:00 2001
From: Mark Brown <broonie@...nel.org>
Date: Tue, 12 Dec 2017 16:56:43 +0000
Subject: [PATCH] regmap: Disable debugfs when locking is disabled

The recently added support for disabling the regmap internal locking left
debugfs enabled for devices with the locking disabled. This is a problem
since debugfs allows userspace to do things like initiate reads from the
hardware which will use the scratch buffers protected by the regmap locking
so could cause data corruption.

For safety address this by just disabling debugfs for these devices. That
is overly conservative since some of the debugfs files just read internal
data structures but it's much simpler to implmement and less likely to
lead to problems with tooling that works with debugfs.

Reported-by: Lars-Peter Clausen <lars@...afoo.de>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/base/regmap/internal.h       | 8 ++++++++
 drivers/base/regmap/regmap-debugfs.c | 3 +++
 drivers/base/regmap/regmap.c         | 1 +
 3 files changed, 12 insertions(+)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 8641183cac2f..53785e0e297a 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -77,6 +77,7 @@ struct regmap {
 	int async_ret;

 #ifdef CONFIG_DEBUG_FS
+	bool debugfs_disable;
 	struct dentry *debugfs;
 	const char *debugfs_name;

@@ -215,10 +216,17 @@ struct regmap_field {
 extern void regmap_debugfs_initcall(void);
 extern void regmap_debugfs_init(struct regmap *map, const char *name);
 extern void regmap_debugfs_exit(struct regmap *map);
+
+static inline void regmap_debugfs_disable(struct regmap *map)
+{
+	map->debugfs_disable = true;
+}
+
 #else
 static inline void regmap_debugfs_initcall(void) { }
 static inline void regmap_debugfs_init(struct regmap *map, const char *name) { }
 static inline void regmap_debugfs_exit(struct regmap *map) { }
+static inline void regmap_debugfs_disable(struct regmap *map) { }
 #endif

 /* regcache core declarations */
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index 36ce3511c733..c8ecefd75d6f 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -529,6 +529,9 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
 	struct regmap_range_node *range_node;
 	const char *devname = "dummy";

+	if (map->debugfs_disable)
+		return;
+
 	/* If we don't have the debugfs root yet, postpone init */
 	if (!regmap_debugfs_root) {
 		struct regmap_debugfs_node *node;
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 54b1aa371c61..df9ca36753ff 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -676,6 +676,7 @@ struct regmap *__regmap_init(struct device *dev,

 	if (config->disable_locking) {
 		map->lock = map->unlock = regmap_lock_unlock_none;
+		regmap_debugfs_disable(map);
 	} else if (config->lock && config->unlock) {
 		map->lock = config->lock;
 		map->unlock = config->unlock;
-- 
2.15.1