Re: Threads (was Re: MSI interrupts)

In article <FoxHP.1477197$eNx6.766449@fx14.iad>,
Scott Lurndal <slp53@pacbell.net> wrote:

Dan Cross wrote:

[snip]
For instance, consider Unix/POSIX `open`: from an API
perspective this simply maps a symbolic file path name to a file
descriptor that can subsequently be used to perform IO on the
named file.  While it is well-known that the interface is
defined so that it can block opening some kinds of devices, for
example, some terminal devices until the line is asserted, that
is not the usual case, and noteably `open` does no IO on the
file itself.  So generally, most programs would expect that it
has no reason to block.

>
The one case where open was a problem on traditional unix was
for line printers.    The open of /dev/lp could block if the
printer (on a centronics port) was not-ready.   And it was
an uninterruptable block, even SIGKILL was blocked.

I'd worry more about, say a pathname that requires traversing
NFS for one reason or another (symlinks, or just on a mounted
filesystem).  Nothing prevents an NFS server from becoming
inaccessible during a lookup.

- Dan C.