Re: is flock broken in 2.4 or 2.5 kernels or what does this mean?

[David Ford <david+cert@blue-labs.org>]

(Alan)
Actually I posted a "is sendmail on crack?" question last month when 
8.12.5 was released and this was in the release notes.  We got a bunch 
of confirmations that Linux flock() was broken due to the accounting.

David

J.A. Magallon wrote:

>On 2002.07.23 Alan Cox wrote:
>  
>
>>On Tue, 2002-07-23 at 15:41, John Covici wrote:
>>    
>>
>>>In the latest release notes of sendmail I have read the following:
>>>
>>>		NOTE: Linux appears to have broken flock() again.  Unless
>>>			the bug is fixed before sendmail 8.13 is shipped,
>>>			8.13 will change the default locking method to
>>>			fcntl() for Linux kernel 2.4 and later.  You may
>>>			want to do this in 8.12 by compiling with
>>>			-DHASFLOCK=0.  Be sure to update other sendmail
>>>			related programs to match locking techniques.
>>>
>>>Can anyone tell me what this is all about -- is there any basis in
>>>reality for what they are saying?
>>>      
>>>
>>First I've heard of it, so it would be useful if someone has access to
>>the sendmail problem report/test in question that shows it and I'll go
>>find out.
>>
>>    
>>
>
>Perhaps if you have your spool over nfs:
>
>man flock:
>
>NOTES
>       flock(2) does not  lock  files  over  NFS.   Use  fcntl(2)
>       instead:  that  does  work  over NFS, given a sufficiently
>       recent version of Linux and a server which supports  lock­
>       ing.
>
>       flock(2)  and fcntl(2) locks have different semantics with
>       respect to forked processes and dup(2).
>
>  
>

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