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callout(9): Allow spin locks use with callout_init_mtx()
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Authored by mav on Sep 2 2021, 12:02 AM.
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Details

Summary

Implement lock_spin()/unlock_spin() lock class methods, moving the assertion to _sleep() instead. Change assertions in callout(9) to allow spin locks for both regular and C_DIRECT_EXEC cases. In case of C_DIRECT_EXEC spin locks are the only locks allowed.

As the first use case allow taskqueue_enqueue_timeout() use on fast task queues. It actually becomes more efficient due to avoided extra context switches in callout(9) thanks to C_DIRECT_EXEC.

Test Plan

Simple test using taskqueue_enqueue_timeout() on fast task queue, including recursively, successfully passes on debug kernel.

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Event Timeline

mav requested review of this revision.Sep 2 2021, 12:02 AM
mav created this revision.

I like this idea and wouldn't object to it.

This revision is now accepted and ready to land.Sep 2 2021, 7:51 AM

Minor tuning to unlock_spin().

This revision now requires review to proceed.Sep 2 2021, 2:01 PM
This revision is now accepted and ready to land.Sep 2 2021, 3:06 PM