April 2008 - Darwin-kernel - lists.apple.com

Re: kernel thread join?
by Duane Murphy 15 Apr '08

15 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com --- At Tue, 15 Apr 2008 14:43:40 +1000, Godfrey van der Linden wrote: >The best IOKit aware equivalent to a condition variable is the >IOCommandGate::commandSleep/commandWakeup APIs. > >However the way you describe the problem the reference counting >solution seems ideal. Especially as it is a data removal cleanup type >of problem. I assume your problem is that you need to execute some >code to do the data cleanup? Is that correct? > >Can you describe the action you want to take on completion? The fundamental problem is that the case that I am working with, the system is either going to sleep, shutting down, or in general going off- line. I can't return from the call that says "you're going off-line" until the other thread has completed and exited. The final stage of the exit of the other thread, records the information about why the thread exited so that it can be brought back up again appropriately. I'm using msleep() and it seems to be doing the job just great. Conveniently all the pieces were there in place; a variable to track the completion, and a mutex lock for that variable. Enter msleep() with a reasonable timeout and a wakeup() call at the end of the thread, and viola. >On 2008-04-15, at 1:45 , Duane Murphy wrote: > >> --- At Mon, 14 Apr 2008 11:48:06 +1000, Godfrey van der Linden wrote: >> >>> There isn't really a 100% reliable way of waiting for a thread to >>> terminate completely. However that isn't really a problem. The key >>> is to recognise what you are really trying to do. >>> >>> Presumably you are trying to clean up resources that the thread may >>> be >>> using? >>> >>> In this case the correct kernel way of cleaning this up is just to >>> reference count your resources. Then it doesn't matter exactly what >>> order the objects get released in. There are a couple of other >>> tricks >>> but the OSObject reference counting will probably get you out of >>> trouble. >> >> Thanks for the idea. Unfortunately, in this case I think I need to >> wait >> for the thread to stop. The thread is processing data. The data is >> going >> to be removed and can't be removed until the processing has been >> halted >> and the removal noted. The waiting thread has received the notice that >> the data is going away and should clean up. >> >> I'm going to use a condition variable to signal the end of the thread. >> >> Now I need to work out how to do that. Any recommendations for a >> kernel >> condition variable? >> >> Thanks for the ideas, >> >>> On 2008-04-12, at 5:08 , Duane Murphy wrote: >>> >>>> What is the equivalent of pthread_join() for a kernel thread? >>>> >>>> I am using IOThreadCreate() to create a new thread. At some later >>>> point >>>> I indicate to that thread to stop. How do I detect that the thread >>>> as exited? >> >> ...Duane >> >> _______________________________________________ >> Do not post admin requests to the list. They will be ignored. >> Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) >> Help/Unsubscribe/Update your Subscription: >> http://lists.apple.com/mailman/options/darwin-kernel/gvdl%40mac.com >> >> This email sent to gvdl(a)mac.com > > ...Duane _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: kernel thread join?
by Godfrey van der Linden 15 Apr '08

15 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Can you describe the action you want to take on completion? Godfrey On 2008-04-15, at 1:45 , Duane Murphy wrote: --- At Mon, 14 Apr 2008 11:48:06 +1000, Godfrey van der Linden wrote: There isn't really a 100% reliable way of waiting for a thread to terminate completely. However that isn't really a problem. The key is to recognise what you are really trying to do. I'm going to use a condition variable to signal the end of the thread. Thanks for the ideas, On 2008-04-12, at 5:08 , Duane Murphy wrote: What is the equivalent of pthread_join() for a kernel thread? I am using IOThreadCreate() to create a new thread. At some later point I indicate to that thread to stop. How do I detect that the thread as exited? ...Duane _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/gvdl%40mac.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… The best IOKit aware equivalent to a condition variable is the IOCommandGate::commandSleep/commandWakeup APIs. However the way you describe the problem the reference counting solution seems ideal. Especially as it is a data removal cleanup type of problem. I assume your problem is that you need to execute some code to do the data cleanup? Is that correct? Presumably you are trying to clean up resources that the thread may be using? In this case the correct kernel way of cleaning this up is just to reference count your resources. Then it doesn't matter exactly what order the objects get released in. There are a couple of other tricks but the OSObject reference counting will probably get you out of trouble. Thanks for the idea. Unfortunately, in this case I think I need to wait for the thread to stop. The thread is processing data. The data is going to be removed and can't be removed until the processing has been halted and the removal noted. The waiting thread has received the notice that the data is going away and should clean up. Now I need to work out how to do that. Any recommendations for a kernel condition variable? This email sent to gvdl(a)mac.com This email sent to site_archiver(a)lists.apple.com

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RE: Use of asynchronous receive at kernel level
by Rick Macklem 14 Apr '08

14 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com On Mon, 14 Apr 2008, Eddy Quicksall wrote: I can see how to call soreceive but I can't see how to get an upcall when data is available. Does anyone have any information on this? I'm not sure if the one specified in the kpi is the same, but an upcall is used by the nfs server. It is called whenever data has been added to the socket's receive queue. You could look in xnu-1228/bsd/nfs for use of it there. rick _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… [stuff snipped] This email sent to site_archiver(a)lists.apple.com

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Re: Use of asynchronous receive at kernel level
by Josh Graessley 14 Apr '08

14 Apr '08

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RE: Use of asynchronous receive at kernel level
by Eddy Quicksall 14 Apr '08

14 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Thread-index: AcieWCVKsGac/3yJSZuqo6YiCr4hrgAAO8gA _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Use of asynchronous receive at kernel level
by Josh Graessley 14 Apr '08

14 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: kernel thread join?
by Duane Murphy 14 Apr '08

14 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com --- At Mon, 14 Apr 2008 11:48:06 +1000, Godfrey van der Linden wrote: >There isn't really a 100% reliable way of waiting for a thread to >terminate completely. However that isn't really a problem. The key >is to recognise what you are really trying to do. > >Presumably you are trying to clean up resources that the thread may be >using? > >In this case the correct kernel way of cleaning this up is just to >reference count your resources. Then it doesn't matter exactly what >order the objects get released in. There are a couple of other tricks >but the OSObject reference counting will probably get you out of >trouble. Thanks for the idea. Unfortunately, in this case I think I need to wait for the thread to stop. The thread is processing data. The data is going to be removed and can't be removed until the processing has been halted and the removal noted. The waiting thread has received the notice that the data is going away and should clean up. I'm going to use a condition variable to signal the end of the thread. Now I need to work out how to do that. Any recommendations for a kernel condition variable? Thanks for the ideas, >On 2008-04-12, at 5:08 , Duane Murphy wrote: > >> What is the equivalent of pthread_join() for a kernel thread? >> >> I am using IOThreadCreate() to create a new thread. At some later >> point >> I indicate to that thread to stop. How do I detect that the thread >> as exited? ...Duane _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… This email sent to site_archiver(a)lists.apple.com

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Re: Single-user mode selector
by Terry Lambert 14 Apr '08

14 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com -- Terry _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… Use the string version of the selector and sysctlbyname(). Expect that MIB-based sysctl() and OID definitions will go away at some point in the future, as they are not automatically extensible without recompilation of the command line tool. The other advantage of by name sysctl() is that you can know if it is supported or not on a given OS version by whether it returns an error, which is helpful to future-proof your applications. That way if you get run on an older version of the OS, you can decide to still run. All that said, the selector itself is not particularly useful, since launchd gets a -s argument in single user mode now, and it's really the only application that should care. On Apr 13, 2008, at 7:07 PM, Tony Scaminaci <friskythecat(a)sbcglobal.net> wrote: I just built my application under Xcode 3.0 and noticed that there's a new parameter returned by sysctl called kern.singleuser. However, I can't find a sysctl selector for this in sysctl.h. I was using KERN_SECURELVL in previous OS versions to determine whether I was running in single-user mode but this selector now returns 0 in multiuser mode under Leopard. What is the selector for kern.singleuser? _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/tlambert%40apple.com This email sent to tlambert(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: Single-user mode selector
by Shantonu Sen 14 Apr '08

14 Apr '08

site_archiver(a)lists.apple.com Delivered-To: darwin-kernel(a)lists.apple.com Shantonu Sent from my MacBook On Apr 13, 2008, at 7:07 PM, Tony Scaminaci wrote: _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.… What resource are you really looking for that is not present in single user mode? I just built my application under Xcode 3.0 and noticed that there's a new parameter returned by sysctl called kern.singleuser. However, I can't find a sysctl selector for this in sysctl.h. I was using KERN_SECURELVL in previous OS versions to determine whether I was running in single-user mode but this selector now returns 0 in multiuser mode under Leopard. What is the selector for kern.singleuser? _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/ssen%40apple.com This email sent to ssen(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Single-user mode selector
by Tony Scaminaci 14 Apr '08

14 Apr '08

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