linux-kernel - [PATCH] Staging:dgap:dgap_tty.c: Upgraded driver to use Mutex instead of semaphore

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Date:	Thu, 17 Apr 2014 21:25:32 +0530
From:	Kumar Gaurav <kumargauravgupta3@...il.com>
To:	gregkh@...uxfoundation.org, lidza.louina@...il.com
Cc:	driverdev-devel@...uxdriverproject.org, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
	Kumar Gaurav <kumargauravgupta3@...il.com>
Subject: [PATCH] Staging:dgap:dgap_tty.c: Upgraded driver to use Mutex instead of semaphore

dgap driver uses semaphore for obtaining lock. I upgraded it to use MUTEX.

Signed-off-by: Kumar Gaurav <kumargauravgupta3@...il.com>
---
 drivers/staging/dgap/dgap_tty.c |   17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/dgap/dgap_tty.c b/drivers/staging/dgap/dgap_tty.c
index 2a7a372..0ca72a2 100755
--- a/drivers/staging/dgap/dgap_tty.c
+++ b/drivers/staging/dgap/dgap_tty.c
@@ -52,7 +52,7 @@
 #include <asm/uaccess.h>	/* For copy_from_user/copy_to_user */
 #include <asm/io.h>		/* For read[bwl]/write[bwl] */
 #include <linux/pci.h>
-
+#include<linux/mutex.h>
 #include "dgap_driver.h"
 #include "dgap_tty.h"
 #include "dgap_types.h"
@@ -61,18 +61,12 @@
 #include "dgap_conf.h"
 #include "dgap_sysfs.h"
 
-#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,37)
-#define init_MUTEX(sem)         sema_init(sem, 1)
-#define DECLARE_MUTEX(name)     \
-        struct semaphore name = __SEMAPHORE_INITIALIZER(name, 1)
-#endif
-
 /*
  * internal variables
  */
 static struct board_t	*dgap_BoardsByMajor[256];
 static uchar		*dgap_TmpWriteBuf = NULL;
-static DECLARE_MUTEX(dgap_TmpWriteSem);
+static DEFINE_MUTEX(dgap_TmpWriteSem);
 
 /*
  * Default transparent print information.
@@ -2004,12 +1998,11 @@ static int dgap_tty_write(struct tty_struct *tty, const unsigned char *buf, int
 		 * the board.
 		 */
 		/* we're allowed to block if it's from_user */
-		if (down_interruptible(&dgap_TmpWriteSem)) {
+		if (mutex_lock_interruptible(&dgap_TmpWriteSem))
 			return (-EINTR);
-		}
 
 		if (copy_from_user(dgap_TmpWriteBuf, (const uchar __user *) buf, count)) {
-			up(&dgap_TmpWriteSem);
+			mutex_unlock(&dgap_TmpWriteSem);
 			printk("Write: Copy from user failed!\n");
 			return -EFAULT;
 		}
@@ -2093,7 +2086,7 @@ static int dgap_tty_write(struct tty_struct *tty, const unsigned char *buf, int
 
 	if (from_user) {
 		DGAP_UNLOCK(ch->ch_lock, lock_flags);
-		up(&dgap_TmpWriteSem);
+		mutex_unlock(&dgap_TmpWriteSem);
 	} 
 	else {
 		DGAP_UNLOCK(ch->ch_lock, lock_flags);
-- 
1.7.9.5

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