Date: Thu, 11 Aug 2005 17:07:06 -0600 From: Scott Long <scottl@samsco.org> To: John Baldwin <jhb@FreeBSD.org> Cc: freebsd-current@FreeBSD.org, Joerg Pulz <Joerg.Pulz@frm2.tum.de> Subject: Re: 6.0-BETA2: taskqueue_drain for if_xl.c:2796 Message-ID: <42FBDA1A.9000204@samsco.org> In-Reply-To: <200508111803.41851.jhb@FreeBSD.org> References: <20050811220017.A72944@hades.admin.frm2> <200508111741.15983.jhb@FreeBSD.org> <200508111803.41851.jhb@FreeBSD.org>
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John Baldwin wrote: > On Thursday 11 August 2005 05:41 pm, John Baldwin wrote: > >>On Thursday 11 August 2005 04:09 pm, Joerg Pulz wrote: >> >>>Hi, >>> >>>with a fresh installed 6.0-BETA2 i get this when xl(4) gets configured at >>>the system startup. >>>System is P3-800MHz SMP. dmesg is attached. >> >>I'm working on fixes for this. Ping me in a day or so for a patch. > > > Ok, I've got a patch. I added a taskqueue_stop() function to bring > taskqueue's a bit closer inline with the callout*() API and use > taskqueue_stop() in xl_stop() as it is ok to be called with locks held and > doesn't block. The xl task handler function now bails if IFF_DRV_RUNNING is > clear, and I added a taskqueue_drain() in detach to make sure we were > finished with the mutex and function before detach finishes. Unfortunately, > the patch is to HEAD, but you can probably get it to work on 6.x by changing > if_drv_flags to if_flags and IFF_DRV_RUNNING to IFF_RUNNING on 6.x. > > http://www.FreeBSD.org/~jhb/patches/xl_locking It looks like taskqueue_stop merely removes a pending task from the queue, it doesn't protect against there being a task already running and/or sleeping. I know that you're looking for the convenience of being able to cancel a taskqueue without having to worry about locks, but ignoring the possibility of an in-progress task is dangerous. It's incovenient, but it's the price of concurrency in the kernel. I've objected to callout_stop for the same reason. Never the less, if you're looking to have a similar API as callout_*, why not follow their model and have _taskqueue_stop_safe() ? Scott
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