Date: Thu, 27 Mar 2014 16:46:57 +0800 From: David Xu <davidxu@freebsd.org> To: Mateusz Guzik <mjguzik@gmail.com> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org, Mateusz Guzik <mjg@FreeBSD.org> Subject: Re: svn commit: r263755 - head/sys/kern Message-ID: <5333E581.1000100@freebsd.org> In-Reply-To: <20140327083730.GA22942@dft-labs.eu> References: <201403252330.s2PNUaei052956@svn.freebsd.org> <5333D70D.7050306@freebsd.org> <20140327083730.GA22942@dft-labs.eu>
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On 2014/03/27 16:37, Mateusz Guzik wrote: > On Thu, Mar 27, 2014 at 03:45:17PM +0800, David Xu wrote: >> I think the async process pointer can be cleared when a process exits >> by registering an event handler. please see attached patch. >> > > Sure, but I'm not very fond of this solution. > > This is a rather obscure bug you wont hit unless you explicitly try, > and even then you need root privs by default. > OK, but I don't like the bug exists in kernel. It is not obscure for me, I can run "shutdown now" command, and insert a device, and then the kernel will write garbage data into freed memory space. > As such writing a callback function which will be executed for all exiting > processes seems unjustified for me. > > Ideally we would get some mechanism which would allow to register > callbacks for events related to given entity. Then it could be used to > provide a "call this function when process p exits", amongst other things. > Yes, but the callback itself is cheap enough and is not worth to be per-entity entry.
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