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    SubjectRe: [patch] updates for the pipe code
    Manfred Spraul writes:
    > Richard Gooch wrote:
    >
    > > What about the problem I
    > > reported back on 16-FEB? It's still happening with 2.3.48. The problem
    > > does not occur with 2.2.14.
    > >
    > > > Hi, all. I've been noticing odd behaviour with named pipes under
    > > > recent 2.3.x kernels (at least since 2.3.36 and possibly before).
    > > >
    > > > If you open a FIFO with O_RDONLY and then call read(2), and then
    > > > another process writes to the FIFO, the read(2) call doesn't return. A
    > > > subsequent writer process does wake up the reader, however.
    > > >
    > > > Has anybody else noticed this behaviour?
    > >
    > > I've noticed this problem on UP and SMP systems. It doesn't always
    > > happen, but it *does* happen :-(
    > >
    > Hmm.
    > I didn't notice a bug when I rewrote the locking.
    > Do you have a test application? Is someone using O_NONBLOCK, which end
    > of the fifo is opened first?

    I don't really have a test application. It's my shell scripts for
    synchronising my window manager and X client. The reader is cat and
    the writer is tcsh/echo.

    No-one should be doing O_NONBLOCK. I don't really know which is
    starting first. Earlier in 2.3.4x I had some testcode which sometimes
    demonstrated the same problem, but that testcode hasn't failed yet
    with 2.3.48.

    Not once have I seen the problem with 2.2.14.

    Regards,

    Richard....
    Permanent: rgooch@atnf.csiro.au
    Current: rgooch@ras.ucalgary.ca

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