Re: Opening of blocking FIFOs not reliable?

[Manfred Spraul]

Teemu wrote:

> Opening a FIFO for WR_ONLY should release a previously blocked RD_ONLY 
> open. I suspect this is not guaranteed on a heavily loaded Linux box.
>  
Do you have a test case?
IIRC we had that bug, and it was fixed by adding PIPE_WCOUNTER:
PIPE_WRITERS counts the number of writers. This one is decreased during 
close(). PIPE_WCOUNTER counts how often a writer was seen. It's never 
decreased. Readers that wait for a writer wait until PIPE_WCOUNTER 
changes, they do not look at PIPE_WRITERS.

--
   Manfred
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