PERFORCE change 129919 for review

[Peter Wemm]

http://perforce.freebsd.org/chv.cgi?CH=129919

Change 129919 by peter at peter_daintree on 2007/12/01 23:58:58

	I'd like to change thread_stash() calls to thread_free(), but I'm not
	yet certain if the context allows that.

Affected files ...

.. //depot/projects/bike_sched/sys/kern/kern_thread.c#8 edit

Differences ...

==== //depot/projects/bike_sched/sys/kern/kern_thread.c#8 (text+ko) ====

@@ -66,10 +66,19 @@
 SYSCTL_INT(_kern_threads, OID_AUTO, max_threads_hits, CTLFLAG_RD,
 	&max_threads_hits, 0, "");
 
+/*
+ * I'm unsure if this is safe to remove.  thread_free might not be able
+ * to be called from the contexts that thread_stash is.
+ */
+#define ZOMBIES 1
+#ifdef ZOMBIES
 TAILQ_HEAD(, thread) zombie_threads = TAILQ_HEAD_INITIALIZER(zombie_threads);
 static struct mtx zombie_lock;
 MTX_SYSINIT(zombie_lock, &zombie_lock, "zombie lock", MTX_SPIN);
 
+static void thread_zombie(struct thread *);
+#endif
+
 struct mtx tid_lock;
 static struct unrhdr *tid_unrhdr;
 
@@ -220,7 +229,36 @@
 	    16 - 1, 0);
 }
 
+#ifdef ZOMBIES
 /*
+ * Place an unused thread on the zombie list.
+ * Use the slpq as that must be unused by now.
+ */
+void
+thread_zombie(struct thread *td)
+{
+	mtx_lock_spin(&zombie_lock);
+	TAILQ_INSERT_HEAD(&zombie_threads, td, td_slpq);
+	mtx_unlock_spin(&zombie_lock);
+}
+#endif
+
+/*
+ * Release a thread that has exited after cpu_throw().
+ */
+void
+thread_stash(struct thread *td)
+{
+	atomic_subtract_rel_int(&td->td_proc->p_exitthreads, 1);
+#ifdef ZOMBIES
+	thread_zombie(td);
+#else
+	thread_free(td);	/* unsafe here? */
+#endif
+}
+
+#ifdef ZOMBIES
+/*
  * Reap zombie kse resource.
  */
 void
@@ -247,6 +285,7 @@
 		}
 	}
 }
+#endif
 
 /*
  * Allocate a thread.
@@ -256,7 +295,9 @@
 {
 	struct thread *td;
 
+#ifdef ZOMBIES
 	thread_reap(); /* check if any zombies to get */
+#endif
 
 	td = (struct thread *)uma_zalloc(thread_zone, M_WAITOK);
 	KASSERT(td->td_kstack == 0, ("thread_alloc got thread with kstack"));
@@ -423,7 +464,9 @@
 		sched_relinquish(curthread);
 	cpu_thread_clean(td);
 	crfree(td->td_ucred);
+#ifdef ZOMBIES
 	thread_reap();	/* check for zombie threads etc. */
+#endif
 }
 
 /*