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authorKay Sievers <kay@vrfy.org>2012-05-10 04:32:53 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-09 20:29:59 -0700
commit5c5d5ca51abd728c8de3be43ffd6bb00f977bfcd (patch)
tree737f0efbb6971c7055d7b07dacc79a2922bd19c7 /kernel/printk.c
parent7f3a781d6fd81e397c3928c9af33f1fc63232db6 (diff)
printk() - do not merge continuation lines of different threads
This prevents the merging of printk() continuation lines of different threads, in the case they race against each other. It should properly isolate "atomic" single-line printk() users from continuation users, to make sure the single-line users will never be merged with the racy continuation ones. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/printk.c')
-rw-r--r--kernel/printk.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index 7b432951f91..301fb0f09fb 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1230,12 +1230,13 @@ asmlinkage int vprintk_emit(int facility, int level,
static size_t buflen;
static int buflevel;
static char textbuf[LOG_LINE_MAX];
+ static struct task_struct *cont;
char *text = textbuf;
size_t textlen;
unsigned long flags;
int this_cpu;
bool newline = false;
- bool cont = false;
+ bool prefix = false;
int printed_len = 0;
boot_delay_msec();
@@ -1295,20 +1296,16 @@ asmlinkage int vprintk_emit(int facility, int level,
case '0' ... '7':
if (level == -1)
level = text[1] - '0';
- text += 3;
- textlen -= 3;
- break;
- case 'c': /* KERN_CONT */
- cont = true;
case 'd': /* KERN_DEFAULT */
+ prefix = true;
+ case 'c': /* KERN_CONT */
text += 3;
textlen -= 3;
- break;
}
}
- if (buflen && (!cont || dict)) {
- /* no continuation; flush existing buffer */
+ if (buflen && (prefix || dict || cont != current)) {
+ /* flush existing buffer */
log_store(facility, buflevel, NULL, 0, buf, buflen);
printed_len += buflen;
buflen = 0;
@@ -1342,6 +1339,10 @@ asmlinkage int vprintk_emit(int facility, int level,
dict, dictlen, text, textlen);
printed_len += textlen;
}
+ cont = NULL;
+ } else {
+ /* remember thread which filled the buffer */
+ cont = current;
}
/*