linux-kernel - [PATCH 1/3] fastrpc: always use fl->lock and remove fl->mutex

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Date:   Wed, 17 Feb 2021 22:20:53 -0500
From:   Jonathan Marek <jonathan@...ek.ca>
To:     linux-arm-msm@...r.kernel.org
Cc:     srinivas.kandagatla@...aro.org, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/3] fastrpc: always use fl->lock and remove fl->mutex

Fix the broken behavior of having a separate mutex for locking at this
place, and use the same spinlock that is used to add/remove from the list.

Signed-off-by: Jonathan Marek <jonathan@...ek.ca>
---
 drivers/misc/fastrpc.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index f12e909034ac..4fabea0c1551 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -230,8 +230,6 @@ struct fastrpc_user {
 	int pd;
 	/* Lock for lists */
 	spinlock_t lock;
-	/* lock for allocations */
-	struct mutex mutex;
 };
 
 static void fastrpc_free_map(struct kref *ref)
@@ -267,16 +265,16 @@ static int fastrpc_map_find(struct fastrpc_user *fl, int fd,
 {
 	struct fastrpc_map *map = NULL;
 
-	mutex_lock(&fl->mutex);
+	spin_lock(&fl->lock);
 	list_for_each_entry(map, &fl->maps, node) {
 		if (map->fd == fd) {
 			fastrpc_map_get(map);
 			*ppmap = map;
-			mutex_unlock(&fl->mutex);
+			spin_unlock(&fl->lock);
 			return 0;
 		}
 	}
-	mutex_unlock(&fl->mutex);
+	spin_unlock(&fl->lock);
 
 	return -ENOENT;
 }
@@ -1200,7 +1198,6 @@ static int fastrpc_device_release(struct inode *inode, struct file *file)
 	fastrpc_session_free(cctx, fl->sctx);
 	fastrpc_channel_ctx_put(cctx);
 
-	mutex_destroy(&fl->mutex);
 	kfree(fl);
 	file->private_data = NULL;
 
@@ -1222,7 +1219,6 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
 
 	filp->private_data = fl;
 	spin_lock_init(&fl->lock);
-	mutex_init(&fl->mutex);
 	INIT_LIST_HEAD(&fl->pending);
 	INIT_LIST_HEAD(&fl->maps);
 	INIT_LIST_HEAD(&fl->mmaps);
@@ -1233,7 +1229,6 @@ static int fastrpc_device_open(struct inode *inode, struct file *filp)
 	fl->sctx = fastrpc_session_alloc(cctx);
 	if (!fl->sctx) {
 		dev_err(&cctx->rpdev->dev, "No session available\n");
-		mutex_destroy(&fl->mutex);
 		kfree(fl);
 
 		return -EBUSY;
-- 
2.26.1