Date: Thu, 18 Jul 2002 16:19:51 -0400 (EDT) From: John Baldwin <jhb@FreeBSD.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: current@FreeBSD.ORG, Alfred Perlstein <bright@mu.org> Subject: Re: Questions about kern_descrip.c Message-ID: <XFMail.20020718161933.jhb@FreeBSD.org> In-Reply-To: <200207181909.g6IJ9hTq019460@apollo.backplane.com>
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On 18-Jul-2002 Matthew Dillon wrote: > >: >:* 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. If you really wanted to do this you could just use '(struct file *)1' or some other evil, but I really don't think it's necessary. -- John Baldwin <jhb@FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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