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Subject[PATCH] w1: do not unlock unheld list_mutex in __w1_remove_master_device()
Date
w1_process_callbacks() expects to be called with dev->list_mutex held,
but it is the fact only in w1_process(). __w1_remove_master_device()
calls w1_process_callbacks() after it releases list_mutex.

The patch fixes __w1_remove_master_device() to acquire list_mutex
for w1_process_callbacks(). It is implemented by moving
w1_process_callbacks() functionality to __w1_process_callbacks()
and adding a wrapper with the old name.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
---
drivers/w1/w1.c | 8 +++++---
drivers/w1/w1.h | 13 ++++++++++++-
2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index ff52618cafbe..e507c51512aa 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -1075,12 +1075,14 @@ static void w1_search_process(struct w1_master *dev, u8 search_type)
}

/**
- * w1_process_callbacks() - execute each dev->async_list callback entry
+ * __w1_process_callbacks() - execute each dev->async_list callback entry
* @dev: w1_master device
*
+ * The w1 master list_mutex must be held.
+ *
* Return: 1 if there were commands to executed 0 otherwise
*/
-int w1_process_callbacks(struct w1_master *dev)
+int __w1_process_callbacks(struct w1_master *dev)
{
int ret = 0;
struct w1_async_cmd *async_cmd, *async_n;
@@ -1122,7 +1124,7 @@ int w1_process(void *data)
/* Note, w1_process_callback drops the lock while processing,
* but locks it again before returning.
*/
- if (!w1_process_callbacks(dev) && jremain) {
+ if (!__w1_process_callbacks(dev) && jremain) {
/* a wake up is either to stop the thread, process
* callbacks, or search, it isn't process callbacks, so
* schedule a search.
diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
index 734dab7fc687..e357321a5e13 100644
--- a/drivers/w1/w1.h
+++ b/drivers/w1/w1.h
@@ -341,9 +341,20 @@ extern int w1_max_slave_ttl;
extern struct list_head w1_masters;
extern struct mutex w1_mlock;

-extern int w1_process_callbacks(struct w1_master *dev);
+extern int __w1_process_callbacks(struct w1_master *dev);
extern int w1_process(void *);

+static inline int w1_process_callbacks(struct w1_master *dev)
+{
+ int ret;
+
+ mutex_lock(&dev->list_mutex);
+ ret = __w1_process_callbacks(dev);
+ mutex_unlock(&dev->list_mutex);
+ return ret;
+}
+
+
#endif /* __KERNEL__ */

#endif /* __W1_H */
--
1.8.3.2


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