Date: Fri, 12 Nov 2010 09:56:04 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: freebsd-current@freebsd.org Cc: Matthew Fleming <matthew.fleming@isilon.com> Subject: Re: sleep bug in taskqueue(9) Message-ID: <201011120956.04501.hselasky@c2i.net> In-Reply-To: <06D5F9F6F655AD4C92E28B662F7F853E039E389A@seaxch09.desktop.isilon.com> References: <06D5F9F6F655AD4C92E28B662F7F853E039E389A@seaxch09.desktop.isilon.com>
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On Thursday 29 April 2010 01:59:58 Matthew Fleming wrote: > It looks to me like taskqueue_drain(taskqueue_thread, foo) will not > correctly detect whether or not a task is currently running. The check > is against a field in the taskqueue struct, but for the taskqueue_thread > queue with more than one thread, multiple threads can simultaneously be > running a task, thus stomping over the tq_running field. > > I have not seen any problem with the code as-is in actual use, so this > is purely an inspection bug. > > The following patch should fix the problem. Because it changes the size > of struct task I'm not sure if it would be suitable for MFC. > 1) The u_char is going to leave a hole in that structure on ARM platforms for example. 2) The existing taskqueue implementation also has a missing check for the pending count wrapping to zero. I.E. it should stick at 0xFFFF and not wrap to 0. --HPS
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