linux-kernel - [PATCH 04/14] vc: Locking clean up

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Date:	Thu, 01 Apr 2010 17:04:59 +0100
From:	Alan Cox <alan@...ux.intel.com>
To:	linux-kernel@...r.kernel.org
Subject: [PATCH 04/14] vc: Locking clean up

The virtual console layer uses the BKL for various things that don't really
need it. Clean them out.

Signed-off-by: Alan Cox <alan@...ux.intel.com>
---

 drivers/char/selection.c |    4 ++++
 drivers/char/vt.c        |    8 +++++---
 2 files changed, 9 insertions(+), 3 deletions(-)


diff --git a/drivers/char/selection.c b/drivers/char/selection.c
index f97b9e8..6e79340 100644
--- a/drivers/char/selection.c
+++ b/drivers/char/selection.c
@@ -26,6 +26,7 @@
 #include <linux/selection.h>
 #include <linux/tiocl.h>
 #include <linux/console.h>
+#include <linux/smp_lock.h>
 
 /* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */
 #define isspace(c)	((c) == ' ')
@@ -312,6 +313,8 @@ int paste_selection(struct tty_struct *tty)
 	struct  tty_ldisc *ld;
 	DECLARE_WAITQUEUE(wait, current);
 
+	lock_kernel();
+
 	acquire_console_sem();
 	poke_blanked_console();
 	release_console_sem();
@@ -335,5 +338,6 @@ int paste_selection(struct tty_struct *tty)
 	__set_current_state(TASK_RUNNING);
 
 	tty_ldisc_deref(ld);
+	unlock_kernel();
 	return 0;
 }
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index bd1d116..501ca9e 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -282,7 +282,12 @@ static inline unsigned short *screenpos(struct vc_data *vc, int offset, int view
 
 static inline void scrolldelta(int lines)
 {
+	lock_kernel();
+	/* FIXME */
+	/* scrolldelta needs some kind of consistency lock, but the BKL was
+	   and still is not protecting versus the scheduled back end */
 	scrollback_delta += lines;
+	unlock_kernel();
 	schedule_console_callback();
 }
 
@@ -2604,8 +2609,6 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 		return -EFAULT;
 	ret = 0;
 
-	lock_kernel();
-
 	switch (type)
 	{
 		case TIOCL_SETSEL:
@@ -2680,7 +2683,6 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 			ret = -EINVAL;
 			break;
 	}
-	unlock_kernel();
 	return ret;
 }
 

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