Messages in this thread |  | | Date | Fri, 25 Aug 2000 13:10:54 +0200 | From | Andries Brouwer <> | Subject | Re: [FIX] Make deadlock detection work for file locking |
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On Thu, Aug 24, 2000 at 11:38:02PM +0200, almesber@lrc.di.epfl.ch wrote:
> BTW, this is a little off-topic, I kind of wonder what the right semantics > for deadlock detection are with threads. POSIX 1003.1 1996-07-12 says: > > ... If the system detects that sleeping until a > locked region is unlocked would cause a deadlock, the fcntl() > function shall fail with an [EDEADLK] error." > > Okay, that's a little vague already. Now let's make it more interesting > by adding threads: > > Process Thread Action (executed in this order) > A 1 grab lock X > B 1 grab lock Y > A 2 try to get lock Y > B 2 try to get lock X > > Solaris 2.5.1 thinks this is a deadlock. Linux 2.4.0-test1-ac16 thinks > it isn't. I haven't found any definition of what "putting a process to > sleep" means in POSIX.1.
I don't have POSIX in front of me, but I do not think the system must detect deadlock. It is allowed to detect deadlock, and in case it happens to do so EDEADLK is the apprpriate error return.
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