From: Alan Cox <alan@redhat.com>
Date: Mon, 13 Oct 2008 09:41:16 +0000 (+0100)
Subject: vt: remove bogus lock dropping
X-Git-Tag: v2.6.28-rc1~640
X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=bf7a06bcce205705ea5c7675cbb8ea9239ea30a0;p=linux-2.6-omap-h63xx.git

vt: remove bogus lock dropping

For hysterical raisins the vt layer drops and retakes locks in the write
method. This is a left over from the days when user/kernel data was passed
directly to the tty not pre-buffered.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 05ca1c5dcb1..ec94521c311 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -2136,27 +2136,9 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
 	    release_console_sem();
 	    return 0;
 	}
-	release_console_sem();
-
 	orig_buf = buf;
 	orig_count = count;
 
-	/* At this point 'buf' is guaranteed to be a kernel buffer
-	 * and therefore no access to userspace (and therefore sleeping)
-	 * will be needed.  The con_buf_mtx serializes all tty based
-	 * console rendering and vcs write/read operations.  We hold
-	 * the console spinlock during the entire write.
-	 */
-
-	acquire_console_sem();
-
-	vc = tty->driver_data;
-	if (vc == NULL) {
-		printk(KERN_ERR "vt: argh, driver_data _became_ NULL !\n");
-		release_console_sem();
-		goto out;
-	}
-
 	himask = vc->vc_hi_font_mask;
 	charmask = himask ? 0x1ff : 0xff;