From: Laszlo Ersek <lersek@redhat.com>
Date: Fri, 27 Jan 2012 13:34:05 +0000 (+0100)
Subject: keep the PID file locked for the lifetime of the process
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=93dd748b789202af4f5be75412c58ee1ed481b29;p=qemu.git

keep the PID file locked for the lifetime of the process

The lockf() call in qemu_create_pidfile() aims at ensuring mutual
exclusion. We shouldn't close the pidfile on success (as introduced by
commit 1bbd1592), because that drops the lock as well [1]:

    "File locks shall be released on first close by the locking process
    of any file descriptor for the file."

Coverity may complain again about the leaked file descriptor; let's
worry about that later.

v1->v2:
- add reference to 1bbd1592
- explain the intentional fd leak in the source

[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/lockf.html

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---

diff --git a/os-posix.c b/os-posix.c
index 5c437ca12c..e3ed497224 100644
--- a/os-posix.c
+++ b/os-posix.c
@@ -348,6 +348,6 @@ int qemu_create_pidfile(const char *filename)
         return -1;
     }
 
-    close(fd);
+    /* keep pidfile open & locked forever */
     return 0;
 }