Date: Thu, 18 Jul 2002 12:09:43 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Alfred Perlstein <bright@mu.org> Cc: John Baldwin <jhb@FreeBSD.ORG>, current@FreeBSD.ORG Subject: Re: Questions about kern_descrip.c Message-ID: <200207181909.g6IJ9hTq019460@apollo.backplane.com> References: <XFMail.20020718134618.jhb@FreeBSD.org> <200207181840.g6IIe25G019269@apollo.backplane.com> <20020718185538.GJ77219@elvis.mu.org>
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:* Matthew Dillon <dillon@apollo.backplane.com> [020718 11:40] wrote:
:>
:> fdalloc() does not reserve the descriptor number it
:> returns, it simply finds a free slot and says 'this
:> index is a free slot'. Even in the latest -current,
:> fdalloc() releases the fdp lock when it goes to
:> MALLOC so the race appears to still be present.
:
:This is true. I think one way to fix this is to preallocate
:the 'struct file' you're going to put into the array and have
:fdalloc() insert the created file instead of just finding a
:slot. Problem is that it's a bunch of grunt work to do this.
:
:--
:-Alfred Perlstein [alfred@freebsd.org]
:'Instead of asking why a piece of software is using "1970s technology,"
If you do this be careful in regards to open() and close() which
might place the descriptor in a transitory state. You don't want
another thread picking the descriptor up while it is in that
state.
-Matt
Matthew Dillon
<dillon@backplane.com>
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