Messages in this thread | | | Date | Mon, 29 Apr 2013 14:23:50 -0700 | From | Sarah Sharp <> | Subject | Re: [PATCH] PCI: Fix racing for pci device removing via sysfs |
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On Mon, Apr 29, 2013 at 11:21:42AM -0700, Greg Kroah-Hartman wrote: > On Mon, Apr 29, 2013 at 11:15:50AM -0700, Bjorn Helgaas wrote: > > On Mon, Apr 29, 2013 at 08:19:10AM -0700, Yinghai Lu wrote: > > > On Mon, Apr 29, 2013 at 3:04 AM, Gu Zheng <guz.fnst@cn.fujitsu.com> wrote: > > > > On 04/27/2013 05:01 AM, Yinghai Lu wrote: > > > >> On Fri, Apr 26, 2013 at 1:53 PM, Bjorn Helgaas <bhelgaas@google.com> wrote: > > > >>> > > > >>> You can't be serious. This is a disgusting mess. Checking a list > > > >>> pointer for LIST_POISON1? As far as I'm concerned, this is a waste of > > > >>> my time. > > > > > > looks like xhci is using that LIST_POISON1 ... > > > > > Maybe my allergic reaction to your use of LIST_POISON1 is unjustified, > > but I am dubious about the idea that xhci was the only place that needed > > it before now, and we just happened to find one more place in PCI that > > needs it. That doesn't make sense because good design patterns are used > > many times, not just once or twice. > > > > I thought the whole point of the get/put scheme was that if we had a > > pointer to a correctly reference-counted object, we didn't need to check > > whether the object was still valid because the object remains valid until > > all the references are released. > > You are correct, you shouldn't have to worry about that. If you have to > do something like the LIST_POISON test, something is really wrong.
All right, I'll take a look at the xHCI code. From a brief glance, both places that use LIST_POISON are handling a timed-out command. The command handling in xHCI needs to get completely reworked anyway, due to other race conditions.
Were you suggesting I use the get/put scheme in the xHCI driver, or was that for Yinghai?
Sarah Sharp
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