Bug 2204

Summary: Team can hang when stderr is a file.
Product: Ports & Packages Reporter: dawes <dawes>
Component: Individual Port(s)Assignee: Joerg Wunsch <joerg>
Status: Closed FIXED    
Severity: Affects Only Me CC: dawes
Priority: Normal    
Version: Latest   
Hardware: Any   
OS: Any   
Attachments:
Description Flags
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Description dawes 1996-12-13 06:00:01 UTC 
I've seen team hang when stderr is a file.  'top' reports that it is
stuck in lockf.

Fix: I haven't looked into this very deeply, but #undef'ing F_SETLKW seems to
avoid the problem.  This is already done for SunOS (maybe for the same
reason?).

How-To-Repeat: 
Run team with stderr set to a file.  Sometimes it hangs.
Comment 1 Joerg Wunsch freebsd_committer freebsd_triage 1996-12-13 13:32:25 UTC 
Responsible Changed
From-To: freebsd-ports->joerg

I'm the maintainer.
Comment 2 Joerg Wunsch 1996-12-14 13:16:09 UTC 
As dawes@physics.usyd.edu.au wrote:

> I've seen team hang when stderr is a file.  'top' reports that it is
> stuck in lockf.

> I haven't looked into this very deeply, but #undef'ing F_SETLKW seems to
> avoid the problem.  This is already done for SunOS (maybe for the same
> reason?).

I think team's error is it that it does both locking methods, fcntl()
and flock(), if either F_SETLKW as LOCK_EX are available.  Since they
finally go into the same common code path in the kernel, this might
cause the deadlock.  I believe the code would be correctly written as:

{
# if (defined F_SETLKW)
    struct flock l;
    l.l_whence = 0; l.l_start = 0L; l.l_len = 0L;
    l.l_type = F_WRLCK; fcntl(fileno(stderr),F_SETLKW,&l);
# elif (defined LOCK_EX)
    flock(fileno(stderr),LOCK_EX);
# endif
  fprintf(stderr,a,b,c,d,e,f,g,h,i);
# if (defined LOCK_EX)
    flock(fileno(stderr),LOCK_UN);
# elif (defined F_SETLKW)
    l.l_type = F_UNLCK; fcntl(fileno(stderr),F_SETLKW,&l);
# endif
}

Since flock() doesn't suffer from the braindeadness mentioned in the
fcntl(2) man page, i'll add your suggested patch however.

-- 
cheers, J"org

joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)
Comment 3 Joerg Wunsch freebsd_committer freebsd_triage 1996-12-14 13:25:56 UTC 
State Changed
From-To: open->closed

Suggested fix dropped into the `patches' directory. 

Thanks!