kern/41549: Sometimes fcntl(,F_SETLK)'s lock remains after the process exits.

[QFH02545%nifty.com@localhost]

>Number:         41549
>Category:       kern
>Synopsis:       Sometimes fcntl(,F_SETLK)'s lock remains after the process 
>exits.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Jun 06 05:40:00 +0000 2009
>Originator:     HITOSHI OSADA
>Release:        NetBSD 5.99.13 (2009/06/05)
>Organization:
None
>Environment:
System: NetBSD amd690g 5.99.13 NetBSD 5.99.13 (AMD690G) #3: Thu Jun 4 21:14:26 
JST 2009 root@amd690g:/NetBSD-obj/src-obj/sys/arch/amd64/compile/AMD690G amd64
Architecture: x86_64
Machine: amd64

>Description:
 Sometimes fcntl(, F_SETLK, ...)'s lock remains after the process exits.
 The lock remains until the lockfile removed.

 firefox3 sometimes failed as "firefox already exists but not responding".

>How-To-Repeat:

 $ while ./locktest; do ./locktest; done
 (...doing some heavy jobs at background...)
 locktest: Resource temporarily unavailable
 $ ./locktest
 locktest: Resource temporarily unavailable
 $ rm .testlockfile
 $ ./locktest
 $

locktest.c:
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

/*
 * Codes from firefox-3.0.10 (nsProfileLock.cpp)
 */
int mLockFileDesc;
int mHaveLock;

int
locktest(const char *filename)
{
  int rv = 0;
  mLockFileDesc = open(filename,
                       O_WRONLY | O_CREAT | O_TRUNC, 0666);
  if (mLockFileDesc != -1)
    {
      struct flock lock;

      lock.l_start = 0;
      lock.l_len = 0; 
      lock.l_type = F_WRLCK;
      lock.l_whence = SEEK_SET;

      struct flock testlock = lock;
      if (fcntl(mLockFileDesc, F_GETLK, &testlock) == -1)
        {
          close(mLockFileDesc);
          mLockFileDesc = -1;
          rv = -1;
        }
      else if (fcntl(mLockFileDesc, F_SETLK, &lock) == -1)
        {
          close(mLockFileDesc);
          mLockFileDesc = -1;
          perror("locktest");
          if (errno == EAGAIN || errno == EACCES)
            rv = -2;
          else
            rv = -1;
        }
      else
        mHaveLock = 1;
    }
  else
    {
      printf("Failed to open lock file.");
      rv = -1;
    }
  return rv;
}

int
main(void)
{
  return (locktest(".testlockfile") * -1);
}

>Fix: