Re: Deadlock in My KEXT with NKE

12 Feb 2004

      Ok I tend to not explain what I am doing real well, sorry about that.

I don't want to hold the funnel while it is sleeping, but keeping the

state as it was before it slept.

But the most important thing I am trying to do here is make it so that

the Thread is sleeping while work is being done by the daemon so that

it doesn't do a while loop without sleeping in the kernel,  here is my

while loop:

work_to_do = 1;

				//int stuff = 0;

				while(conditional_val == 0) {

					(void) tsleep((caddr_t) & so->so_timeo, PSOCK, "Testing", 2 * hz);

				}

				//*top = NULL;

				conditional_val = 0;

				//return EACCES;

				work_to_do = 0;

so as you see in the while loop it sleeps every time it goes through

the loop so it doesn't spend lots of CPU trudging through the loop over

and over.  It does the while loop while the dameon is processing

information.

Also is there a way for the KEXT to detect if a daemon is running?

On Feb 11, 2004, at 7:03 PM, Shawn Erickson wrote:
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I don't think you can or should be able to hold a funnel when/if you
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sleep your thread. Once your thread wakes I believe it gets the funnel
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back before continuing if it held the funnel when it slept.
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Given what you have listed so far I cannot make much sense of what you
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are attempting to do... maybe some else can...?
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-Shawn
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On Feb 11, 2004, at 5:52 PM, Matt Jaffa wrote:
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SO I was reading in the archives that if my NKE send function is
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blocked(or in this case sleeping) it releases control of the funnel,
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this is what could be causeing the Deadlock maybe.
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And I was also reading that you have to lock it so that the state
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isn't changed and won't cause this deadlock,  it pointed me to
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sys/lock.h
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Using this how do I lock that so that it doesn't give up the funnel
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while it is sleeping.
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thanks,
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Matt
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On Feb 11, 2004, at 1:39 PM, Matt Jaffa wrote:
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Hi all,
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I have done alot of researching on this and can't find a way to do
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this.
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I have my KEXT which is a NKE, and I am specifically playing with
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the send function so that
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I can monitor and control all outgoing traffic from my computer.
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I have succeeded in finishing my program, but after using it for a
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little bit
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it goes into Deadlock.
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I look at my code and I can see why.
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In my send function I have it surrounded by the the thread_tunnel
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involving network_flock as to make sure only one send function is
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being dealed with at a time, After which my send function signals a
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global static variable  work_to_do = 1,  that informs the daemon
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which is polling using sysctlbyname(...), that there is work to be
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done, and then in the KEXT's NKE's send function it does a
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while(conditional_val == 0) {
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the functions that causes it to sleep;
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}
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then when the dameon is finished with the work, it signals by
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sysctlbyname   that conditional_val = 1   which causes the NKE's
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send function to get out of the while loop.
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This way is working pretty well, except after awhile of using it, it
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gums up and creates deadlock and also the CFUserNotificationCreate
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in my Daemon stops popping up windows asking for input on what to do
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for a connection,
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And finally the only thing i can do then is hold down the poser
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button to reboot.
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I know probably the while loop is very stupid and dangerous to use
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in the KEXT, it brings up questions like, what if the Daemon failed,
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then it would be in a inifinite loop forever.
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So any suggestions of what to do now, of how to know if the Daemon
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is running and also to block the send function until my dameon is
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done with work and then to notify the NKE. Presently my daemon when
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it first starts up it signals to the KEXT it is running and sets
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that global static variable, but if the daemon were to die,  the
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KEXT wouldn't know.
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Thanks for listening to my blabbing on.
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Matt
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P.S.  I really did research this but I can't find anything on it,
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yeah maybe I don't know how to search well, but please help.
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I hope I explained this as best as possible.
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_______________________________________________
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