From: Guillaume Chazarain <guichaz@yahoo.fr>
Date: Sun, 8 Jan 2006 09:02:43 +0000 (-0800)
Subject: [PATCH] kmsg_write: don't return printk return value
X-Git-Tag: v2.6.16-rc1~775
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cd140a5c1f456f50897af4a2e9a23d228a5fe719;p=linux-2.6

[PATCH] kmsg_write: don't return printk return value

kmsg_write returns with printk, so some programs may be confused by a
successful write() with a return value different than the buffer length.

# /bin/echo something > /dev/kmsg
/bin/echo: write error: Inappropriate ioctl for device

The drawbacks is that the printk return value can no more be quickly
checked from userspace.

Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 91dd669273..a85f3a3614 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -817,7 +817,7 @@ static ssize_t kmsg_write(struct file * file, const char __user * buf,
 			  size_t count, loff_t *ppos)
 {
 	char *tmp;
-	int ret;
+	ssize_t ret;
 
 	tmp = kmalloc(count + 1, GFP_KERNEL);
 	if (tmp == NULL)
@@ -826,6 +826,9 @@ static ssize_t kmsg_write(struct file * file, const char __user * buf,
 	if (!copy_from_user(tmp, buf, count)) {
 		tmp[count] = 0;
 		ret = printk("%s", tmp);
+		if (ret > count)
+			/* printk can add a prefix */
+			ret = count;
 	}
 	kfree(tmp);
 	return ret;