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From: Miroslav Benes <>
To: Evgenii Shatokhin <>
Subject: Re: Patching kthread functions
Date: Fri, 2 Oct 2020 13:53:21 +0200 (CEST)	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

> >> The old function will continue running, right?
> > 
> > Correct. It will, however, call new functions.
> Ah, I see.
> So, I guess, our best bet would be to rewrite the thread function so that it
> contains just the event loop and calls other non-inline functions to actually
> process the requests. And, perhaps, - place klp_update_patch_state() before
> schedule().

Yes, that might be the way. klp_update_patch_state() might not be even 
needed. If the callees are live patched, the kthread would be migrated 
thanks to stack checking once a task leaves the callee.
> This will not help with this particular kernel version but could make it
> possible to live-patch the request-processing functions in the future kernel
> versions. The main thread function will remain unpatchable but it will call
> the patched functions once we switch the patch_state for the thread.

Yes. The only issue is if the intended fix changes the semantics which is 
incompatible between old and new functions (livepatch consistency model is 
explanation if interested).


  reply	other threads:[~2020-10-02 11:53 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30 15:44 Patching kthread functions Evgenii Shatokhin
2020-10-01 11:13 ` Miroslav Benes
2020-10-01 12:43   ` Nicolai Stange
2020-10-01 13:18     ` Evgenii Shatokhin
2020-10-01 13:12   ` Evgenii Shatokhin
2020-10-02 11:53     ` Miroslav Benes [this message]
2020-10-02 12:52       ` Evgenii Shatokhin
2020-10-02 13:06         ` Miroslav Benes
2020-10-01 14:46   ` Petr Mladek
2020-10-01 16:34     ` Evgenii Shatokhin

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