On Thu, Feb 7, 2013 at 2:42 PM, Mantas M. <grawity@xxxxxxxxx> wrote:
> When one process is holding an exclusive lock on a file, and other
> processes are waiting for the lock to be released, the contents of
> /proc/locks look like this:
>
> $ cat /proc/locks
> 1: FLOCK ADVISORY WRITE 431143 00:0f:6325223 0 EOF
> 1: -> FLOCK ADVISORY WRITE 405209 00:0f:6325223 0 EOF
> 1: -> FLOCK ADVISORY WRITE 399578 00:0f:6325223 0 EOF
> 1: -> FLOCK ADVISORY WRITE 434120 00:0f:6325223 0 EOF
> 2: FLOCK ADVISORY WRITE 359765 08:04:28180839 0 EOF
> 3: FLOCK ADVISORY WRITE 359765 08:04:28180837 0 EOF
> 4: POSIX ADVISORY WRITE 434729 08:04:8653261 0 EOF
> 4: -> POSIX ADVISORY WRITE 434737 08:04:8653261 0 EOF
> 5: FLOCK ADVISORY WRITE 359765 08:04:28180836 0 EOF
> 6: ...
>
> If I try to run `lslocks`, it fails to parse the "->" lines and exits
> with an error message:
>
> lslocks: failed to parse pid: 'WRITE'
>
> Can be reproduced by:
>
> touch foo & flock foo -c "sleep 100" & flock foo -c "sleep 100" &
> touch foo & lckdo -w foo sleep 100 & lckdo -w foo sleep 100 &
Hi Mantas,
Thank you for reproducing bit which made creating some sort of fix
quite easy. Karel, and others, what do you think about adding a mode
to output listing which some might say is not a mode at all?
>From 9a71631ffd9181225323747eea971e2cd0d80eb8 Mon Sep 17 00:00:00 2001
From: Sami Kerola <kerolasa@xxxxxx>
Date: Mon, 11 Feb 2013 22:30:49 +0000
Subject: [PATCH] lslocks: print waiting state when necessary
Organization: Lastminute.com
Earlier output was primarily unexpected.
$ flock foo -c "sleep 100" & flock foo -c "sleep 100" & flock foo -c
"sleep 100" & lslocks
[1] 22352
[2] 22353
[3] 22354
lslocks: failed to parse pid: 'WRITE'
This commit adds WAITING mode to output listing. The locks which failed
with earlier version will look the following.
COMMAND PID TYPE SIZE MODE M START END PATH
[...]
flock 22354 FLOCK 0B WAITING 0 0 0
/home/src/util-linux/foo
flock 22352 FLOCK 0B WAITING 0 0 0
/home/src/util-linux/foo
flock 22353 FLOCK 0B WRITE 0 0 0
/home/src/util-linux/foo
Reported-by: Mantas Mikulenas <grawity@xxxxxxxxx>
Signed-off-by: Sami Kerola <kerolasa@xxxxxx>
---
misc-utils/lslocks.8 | 2 +-
misc-utils/lslocks.c | 13 +++++++++++--
2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/misc-utils/lslocks.8 b/misc-utils/lslocks.8
index 24cda14..34f611c 100644
--- a/misc-utils/lslocks.8
+++ b/misc-utils/lslocks.8
@@ -44,7 +44,7 @@ Type of lock, can be FLOCK (created with flock(2))
or POSIX (created with fcntl(
Size of the locked file.
.IP "MODE"
-Lock access permissions (read, write).
+Lock access permissions (read, write, waiting).
.IP "M"
Mandatory state of the lock: 0 if none; 1 if set. (See chmod(1)).
diff --git a/misc-utils/lslocks.c b/misc-utils/lslocks.c
index 0a82129..1e8f51f 100644
--- a/misc-utils/lslocks.c
+++ b/misc-utils/lslocks.c
@@ -226,7 +226,7 @@ static ino_t get_dev_inode(char *str, dev_t *dev)
static int get_local_locks(struct list_head *locks)
{
- int i;
+ int i, waiting;
ino_t inode = 0;
FILE *fp;
char buf[PATH_MAX], *szstr = NULL, *tok = NULL;
@@ -241,6 +241,7 @@ static int get_local_locks(struct list_head *locks)
l = xcalloc(1, sizeof(*l));
INIT_LIST_HEAD(&l->locks);
+ waiting = 0;
for (tok = strtok(buf, " "), i = 0; tok;
tok = strtok(NULL, " "), i++) {
@@ -253,6 +254,11 @@ static int get_local_locks(struct list_head *locks)
case 0: /* ignore */
break;
case 1: /* posix, flock, etc */
+ if (strcmp(tok, "->") == 0) {
+ i--;
+ waiting = 1;
+ continue;
+ }
l->type = xstrdup(tok);
break;
@@ -260,7 +266,10 @@ static int get_local_locks(struct list_head *locks)
l->mandatory = *tok == 'M' ? TRUE : FALSE;
break;
case 3: /* lock mode */
- l->mode = xstrdup(tok);
+ if (waiting)
+ l->mode = xstrdup("WAITING");
+ else
+ l->mode = xstrdup(tok);
break;
case 4: /* PID */
--
1.8.1.3
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