linux-kernel - [PATCH] staging:fixed code to fit tty_driver's kref filed fixed code to fit tty_driver's kref filed for drivers/staging/net/pc300

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Message-Id: <1346074458-2659-1-git-send-email-chenbdchenbd@gmail.com>
Date:	Mon, 27 Aug 2012 21:34:18 +0800
From:	Baodong Chen <chenbdchenbd@...il.com>
To:	gregkh@...uxfoundation.org, jslaby@...e.cz, davem@...emloft.net
Cc:	devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
	Baodong Chen <chenbdchenbd@...il.com>
Subject: [PATCH] staging:fixed code to fit tty_driver's kref filed fixed code to fit tty_driver's kref filed for drivers/staging/net/pc300_tty.c

Signed-off-by: Baodong Chen <chenbdchenbd@...il.com>
---
 drivers/staging/net/pc300_tty.c |   55 ++++++++++++++++++++++-----------------
 1 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/drivers/staging/net/pc300_tty.c b/drivers/staging/net/pc300_tty.c
index 4709f42..91ada93 100644
--- a/drivers/staging/net/pc300_tty.c
+++ b/drivers/staging/net/pc300_tty.c
@@ -46,6 +46,8 @@
 #include <linux/slab.h>
 #include <linux/if.h>
 #include <linux/skbuff.h>
+#include <linux/kref.h>
+
 /* TTY includes */
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
@@ -134,12 +136,26 @@ static void cpc_tty_signal_on(pc300dev_t *pc300dev, unsigned char);
 static int pc300_tiocmset(struct tty_struct *, unsigned int, unsigned int);
 static int pc300_tiocmget(struct tty_struct *);
 
+static void cpc_tty_do_unreg_driver(struct kref *ref);
+
 /* functions called by PC300 driver */
 void cpc_tty_init(pc300dev_t *dev);
 void cpc_tty_unregister_service(pc300dev_t *pc300dev);
 void cpc_tty_receive(pc300dev_t *pc300dev);
 void cpc_tty_trigger_poll(pc300dev_t *pc300dev);
 
+static void cpc_tty_do_unreg_driver(struct kref *ref)
+{
+	struct tty_driver *drv = container_of(ref, struct tty_driver, kref);
+	int ret;
+
+	cpc_tty_unreg_flag = 0;
+
+	res = tty_unregister_driver(drv);
+	if (res)
+		CPC_TTY_DBG("unregister the tty driver error=%d\n", res);
+}
+
 /*
  * PC300 TTY clear "signal"
  */
@@ -239,6 +255,8 @@ void cpc_tty_init(pc300dev_t *pc300dev)
 		/* interface routines from the upper tty layer to the tty driver */
 		tty_set_operations(&serial_drv, &pc300_ops);
 
+		kref_init(&serial_drv.kref);
+
 		/* register the TTY driver */
 		if (tty_register_driver(&serial_drv)) { 
 			printk("%s-tty: Failed to register serial driver! ",
@@ -408,13 +426,9 @@ static void cpc_tty_close(struct tty_struct *tty, struct file *flip)
 
 	CPC_TTY_DBG("%s: TTY closed\n",cpc_tty->name);
 	
-	if (!serial_drv.refcount && cpc_tty_unreg_flag) {
-		cpc_tty_unreg_flag = 0;
-		CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name);
-		if ((res=tty_unregister_driver(&serial_drv))) { 
-			CPC_TTY_DBG("%s: ERROR ->unregister the tty driver error=%d\n",
-							cpc_tty->name,res);
-		}
+	if (cpc_tty_unreg_flag) {
+		CPC_TTY_DBG("%s: checking unregister the tty driver...\n", cpc_tty->name);
+		kref_put(&serial_drv.kref, cpc_tty_do_unreg_driver);
 	}
 	return; 
 } 
@@ -644,13 +658,9 @@ static void cpc_tty_hangup(struct tty_struct *tty)
 		CPC_TTY_DBG("%s: TTY is not opened\n",cpc_tty->name);
 		return ;
 	}
-	if (!serial_drv.refcount && cpc_tty_unreg_flag) {
-		cpc_tty_unreg_flag = 0;
-		CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name);
-		if ((res=tty_unregister_driver(&serial_drv))) { 
-			CPC_TTY_DBG("%s: ERROR ->unregister the tty driver error=%d\n",
-							cpc_tty->name,res);
-		}
+	if (cpc_tty_unreg_flag) {
+		CPC_TTY_DBG("%s: checking unregister the tty driver...\n", cpc_tty->name);
+		kref_put(&serial_drv.kref, cpc_tty_do_unreg_driver);
 	}
 	cpc_tty_signal_off(cpc_tty->pc300dev, CTL_DTR);
 }
@@ -1043,19 +1053,16 @@ void cpc_tty_unregister_service(pc300dev_t *pc300dev)
 		return; 
 	}
 
-	if (--cpc_tty_cnt == 0) { 
-		if (serial_drv.refcount) {
-			CPC_TTY_DBG("%s: unregister is not possible, refcount=%d",
-							cpc_tty->name, serial_drv.refcount);
+	if (--cpc_tty_cnt == 0) {
+		CPC_TTY_DBG("%s: checking unregister the tty driver...\n",
+				cpc_tty->name);
+		res = kref_put(&serial_drv.kref, cpc_tty_do_unreg_driver);
+		if (0 == res) {
+			CPC_TTY_DBG("%s: unregister is not possible\n",
+					cpc_tty->name);
 			cpc_tty_cnt++;
 			cpc_tty_unreg_flag = 1;
 			return;
-		} else { 
-			CPC_TTY_DBG("%s: unregister the tty driver\n", cpc_tty->name);
-			if ((res=tty_unregister_driver(&serial_drv))) { 
-				CPC_TTY_DBG("%s: ERROR ->unregister the tty driver error=%d\n",
-								cpc_tty->name,res);
-			}
 		}
 	}
 	CPC_TTY_LOCK(pc300dev->chan->card,flags);
-- 
1.7.0.4

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