linux-kernel - [PATCH 6/8] Char: rtc, use wait_event

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Date:	Mon, 28 May 2007 15:29:50 +0200 (CEST)
From:	Jiri Slaby <jirislaby@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	<a.zummo@...ertech.it>
Subject: [PATCH 6/8] Char: rtc, use wait_event_interruptible

rtc, use wait_event_interruptible

Signed-off-by: Jiri Slaby <jirislaby@...il.com>

---
commit 62bd843054a7b2b2a3e3003a6b57b6359f199837
tree 7c6912d4ed42581ca46d384ab2467bfb9d9d9dbe
parent 2b7813d0f34703e0a4b18593a3186bdc7e719c06
author Jiri Slaby <jirislaby@...il.com> Sat, 26 May 2007 21:58:54 +0200
committer Jiri Slaby <jirislaby@...il.com> Sat, 26 May 2007 21:58:54 +0200

 drivers/char/rtc.c |   40 +++++++++++++++-------------------------
 1 files changed, 15 insertions(+), 25 deletions(-)

diff --git a/drivers/char/rtc.c b/drivers/char/rtc.c
index 20380a2..787b520 100644
--- a/drivers/char/rtc.c
+++ b/drivers/char/rtc.c
@@ -353,33 +353,26 @@ static ssize_t rtc_read(struct file *file, char __user *buf,
 	if (count != sizeof(unsigned int) && count !=  sizeof(unsigned long))
 		return -EINVAL;
 
-	add_wait_queue(&rtc_wait, &wait);
-
-	do {
-		/* First make it right. Then make it fast. Putting this whole
-		 * block within the parentheses of a while would be too
-		 * confusing. And no, xchg() is not the answer. */
-
-		__set_current_state(TASK_INTERRUPTIBLE);
-		
-		spin_lock_irq (&rtc_lock);
-		data = rtc_irq_data;
-		rtc_irq_data = 0;
-		spin_unlock_irq (&rtc_lock);
-
-		if (data != 0)
-			break;
+	spin_lock_irq (&rtc_lock);
+	data = rtc_irq_data;
+	rtc_irq_data = 0;
+	spin_unlock_irq (&rtc_lock);
 
+	if (data == 0) {
 		if (file->f_flags & O_NONBLOCK) {
 			retval = -EAGAIN;
 			goto out;
 		}
-		if (signal_pending(current)) {
-			retval = -ERESTARTSYS;
+		retval = wait_event_interruptible(rtc_wait, ({
+			spin_lock_irq (&rtc_lock);
+			data = rtc_irq_data;
+			rtc_irq_data = 0;
+			spin_unlock_irq (&rtc_lock);
+			data;
+		}));
+		if (retval)
 			goto out;
-		}
-		schedule();
-	} while (1);
+	}
 
 	if (count == sizeof(unsigned int))
 		retval = put_user(data, (unsigned int __user *)buf) ?: sizeof(int);
@@ -387,10 +380,7 @@ static ssize_t rtc_read(struct file *file, char __user *buf,
 		retval = put_user(data, (unsigned long __user *)buf) ?: sizeof(long);
 	if (!retval)
 		retval = count;
- out:
-	__set_current_state(TASK_RUNNING);
-	remove_wait_queue(&rtc_wait, &wait);
-
+out:
 	return retval;
 #endif
 }
-
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