CVS commit: src/sys/kern

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Sat Jan 23 16:33:49 UTC 2021

Modified Files:
        src/sys/kern: kern_threadpool.c

Log Message:
threadpool(9): Fix synchronization between cancel and dispatch.

- threadpool_cancel_job_async tried to prevent
  threadpool_dispatcher_thread from taking the job by setting
  job->job_thread = NULL and then removing the job from the queue.

- But threadpool_cancel_job_async didn't notice job->job_thread is
  null until after it also removes the job from the queue =>
  double-remove, *boom*.

The solution is to teach threadpool_dispatcher_thread to wait until
it has acquired the job lock to test whether job->job_thread is still
valid before it decides to remove the job from the queue.

Fixes PR kern/55948.

XXX pullup-9


To generate a diff of this commit:
cvs rdiff -u -r1.22 -r1.23 src/sys/kern/kern_threadpool.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.