- Bring back turnstile_empty() which can check to see if an individual
queue on a turnstile is empty. - Add a turnstile_disown() function that allows a thread to give up ownership of a turnstile w/o waking up any waiters.
This commit is contained in:
parent
7734a577e3
commit
f1a4b852dc
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=157844
@ -878,6 +878,56 @@ turnstile_unpend(struct turnstile *ts, int owner_type)
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mtx_unlock_spin(&sched_lock);
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}
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/*
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* Give up ownership of a turnstile. This must be called with the
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* turnstile chain locked.
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*/
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void
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turnstile_disown(struct turnstile *ts)
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{
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struct turnstile_chain *tc;
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struct thread *td;
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u_char cp, pri;
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MPASS(ts != NULL);
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MPASS(ts->ts_owner == curthread);
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tc = TC_LOOKUP(ts->ts_lockobj);
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mtx_assert(&tc->tc_lock, MA_OWNED);
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MPASS(TAILQ_EMPTY(&ts->ts_pending));
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MPASS(!TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) ||
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!TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]));
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/*
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* Remove the turnstile from this thread's list of contested locks
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* since this thread doesn't own it anymore. New threads will
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* not be blocking on the turnstile until it is claimed by a new
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* owner.
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*/
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mtx_lock_spin(&td_contested_lock);
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ts->ts_owner = NULL;
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LIST_REMOVE(ts, ts_link);
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mtx_unlock_spin(&td_contested_lock);
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mtx_unlock_spin(&tc->tc_lock);
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/*
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* Adjust the priority of curthread based on other contested
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* locks it owns. Don't lower the priority below the base
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* priority however.
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*/
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td = curthread;
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pri = PRI_MAX;
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mtx_lock_spin(&sched_lock);
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mtx_lock_spin(&td_contested_lock);
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LIST_FOREACH(ts, &td->td_contested, ts_link) {
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cp = turnstile_first_waiter(ts)->td_priority;
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if (cp < pri)
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pri = cp;
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}
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mtx_unlock_spin(&td_contested_lock);
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sched_unlend_prio(td, pri);
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mtx_unlock_spin(&sched_lock);
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}
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/*
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* Return the first thread in a turnstile.
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*/
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@ -895,6 +945,23 @@ turnstile_head(struct turnstile *ts, int queue)
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return (TAILQ_FIRST(&ts->ts_blocked[queue]));
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}
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/*
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* Returns true if a sub-queue of a turnstile is empty.
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*/
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int
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turnstile_empty(struct turnstile *ts, int queue)
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{
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#ifdef INVARIANTS
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struct turnstile_chain *tc;
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MPASS(ts != NULL);
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MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);
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tc = TC_LOOKUP(ts->ts_lockobj);
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mtx_assert(&tc->tc_lock, MA_OWNED);
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#endif
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return (TAILQ_EMPTY(&ts->ts_blocked[queue]));
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}
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#ifdef DDB
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static void
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print_thread(struct thread *td, const char *prefix)
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@ -85,6 +85,8 @@ void turnstile_adjust(struct thread *, u_char);
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struct turnstile *turnstile_alloc(void);
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void turnstile_broadcast(struct turnstile *, int);
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void turnstile_claim(struct lock_object *);
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void turnstile_disown(struct turnstile *);
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int turnstile_empty(struct turnstile *ts, int queue);
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void turnstile_free(struct turnstile *);
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struct thread *turnstile_head(struct turnstile *, int);
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void turnstile_lock(struct lock_object *);
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