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Fix cpu hotplug atomic sleep issue 

We move the spinlock unlock before the thread creation. This should be
safe because the thread creation code doesn't actually manipulate any
taskq data structures; that's done by the thread once it's created.

We also remove the assertion that the maxthreads is the current threads
plus one; that assertion could fail if multiple hotplug events come in
quick succession, and the first new taskq thread hasn't had a chance to
start processing yet.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
eviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #12714
This commit is contained in:
Paul Dagnelie 2021-11-02 09:23:48 -07:00 committed by GitHub
parent 321c1b6f39
commit 58bf6afd3f
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 6 additions and 5 deletions
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11
module/os/linux/spl/spl-taskq.c
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@ -1298,8 +1298,10 @@ spl_taskq_expand(unsigned int cpu, struct hlist_node *node)
ASSERT(tq); ASSERT(tq);
spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class); spin_lock_irqsave_nested(&tq->tq_lock, flags, tq->tq_lock_class);
if (!(tq->tq_flags & TASKQ_ACTIVE)) if (!(tq->tq_flags & TASKQ_ACTIVE)) {
goto out; spin_unlock_irqrestore(&tq->tq_lock, flags);
return (err);
}
ASSERT(tq->tq_flags & TASKQ_THREADS_CPU_PCT); ASSERT(tq->tq_flags & TASKQ_THREADS_CPU_PCT);
int nthreads = MIN(tq->tq_cpu_pct, 100); int nthreads = MIN(tq->tq_cpu_pct, 100);
@ -1308,13 +1310,12 @@ spl_taskq_expand(unsigned int cpu, struct hlist_node *node)
if (!((tq->tq_flags & TASKQ_DYNAMIC) && spl_taskq_thread_dynamic) && if (!((tq->tq_flags & TASKQ_DYNAMIC) && spl_taskq_thread_dynamic) &&
tq->tq_maxthreads > tq->tq_nthreads) { tq->tq_maxthreads > tq->tq_nthreads) {
ASSERT3U(tq->tq_maxthreads, ==, tq->tq_nthreads + 1); spin_unlock_irqrestore(&tq->tq_lock, flags);
taskq_thread_t *tqt = taskq_thread_create(tq); taskq_thread_t *tqt = taskq_thread_create(tq);
if (tqt == NULL) if (tqt == NULL)
err = -1; err = -1;
return (err);
} }
out:
spin_unlock_irqrestore(&tq->tq_lock, flags); spin_unlock_irqrestore(&tq->tq_lock, flags);
return (err); return (err);
} }