linux-kernel - [PATCH 1/3] staging: dgnc: use a real mutex instead of masquerading a semaphore as a mutex

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Date:	Mon,  6 Apr 2015 00:15:53 +0300
From:	Giedrius Statkevicius <giedrius.statkevicius@...il.com>
To:	lidza.louina@...il.com, markh@...pro.net
Cc:	gregkh@...uxfoundation.org, driverdev-devel@...uxdriverproject.org,
	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	Giedrius Statkevičius 
	<giedrius.statkevicius@...il.com>
Subject: [PATCH 1/3] staging: dgnc: use a real mutex instead of masquerading a semaphore as a mutex

A mutex should be used here (and it's name even says that) so remove the hiding
of a semaphore behind a #define and use a real mutex that the kernel provides.

Signed-off-by: Giedrius Statkevičius <giedrius.statkevicius@...il.com>
---
 drivers/staging/dgnc/dgnc_tty.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/staging/dgnc/dgnc_tty.c b/drivers/staging/dgnc/dgnc_tty.c
index ce4187f..0b9bed4 100644
--- a/drivers/staging/dgnc/dgnc_tty.c
+++ b/drivers/staging/dgnc/dgnc_tty.c
@@ -42,16 +42,12 @@
 #include "dgnc_sysfs.h"
 #include "dgnc_utils.h"
 
-#define init_MUTEX(sem)	 sema_init(sem, 1)
-#define DECLARE_MUTEX(name)     \
-	struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
-
 /*
  * internal variables
  */
 static struct dgnc_board	*dgnc_BoardsByMajor[256];
 static unsigned char		*dgnc_TmpWriteBuf;
-static DECLARE_MUTEX(dgnc_TmpWriteSem);
+static DEFINE_MUTEX(dgnc_TmpWriteSem);
 
 /*
  * Default transparent print information.
@@ -1797,7 +1793,7 @@ static int dgnc_tty_write(struct tty_struct *tty,
 		 * the board.
 		 */
 		/* we're allowed to block if it's from_user */
-		if (down_interruptible(&dgnc_TmpWriteSem))
+		if (mutex_lock_interruptible(&dgnc_TmpWriteSem))
 			return -EINTR;
 
 		/*
@@ -1807,7 +1803,7 @@ static int dgnc_tty_write(struct tty_struct *tty,
 		count -= copy_from_user(dgnc_TmpWriteBuf, (const unsigned char __user *) buf, count);
 
 		if (!count) {
-			up(&dgnc_TmpWriteSem);
+			mutex_unlock(&dgnc_TmpWriteSem);
 			return -EFAULT;
 		}
 
@@ -1855,7 +1851,7 @@ static int dgnc_tty_write(struct tty_struct *tty,
 
 	if (from_user) {
 		spin_unlock_irqrestore(&ch->ch_lock, flags);
-		up(&dgnc_TmpWriteSem);
+		mutex_unlock(&dgnc_TmpWriteSem);
 	} else {
 		spin_unlock_irqrestore(&ch->ch_lock, flags);
 	}
-- 
2.3.5

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