> On Dec 26, 2018, at 4:11 PM, Taylor R Campbell
> <campbell+netbsd-source-change...@mumble.net> wrote:
>
> Caveat: Need to
> take care of the lwp name in threadpool_job_done so that we never
> point at the job_name of a job in oblivion.
Something like this.
Index: kern_threadpool.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_threadpool.c,v
retrieving revision 1.11
diff -u -p -r1.11 kern_threadpool.c
--- kern_threadpool.c 26 Dec 2018 22:16:26 -0000 1.11
+++ kern_threadpool.c 27 Dec 2018 03:46:07 -0000
@@ -107,6 +107,7 @@ TAILQ_HEAD(thread_head, threadpool_threa
struct threadpool_thread {
struct lwp *tpt_lwp;
+ char *tpt_lwp_savedname;
struct threadpool *tpt_pool;
struct threadpool_job *tpt_job;
kcondvar_t tpt_cv;
@@ -695,6 +696,15 @@ threadpool_job_done(struct threadpool_jo
cv_broadcast(&job->job_cv);
job->job_thread = NULL;
+
+ /*
+ * We can safely read this field; it's only modified right before
+ * we call the job work function, and we are only preserving it
+ * use here; no one cares if it conains junk afterward.
+ */
+ lwp_lock(curlwp);
+ curlwp->l_name = job->job_thread->tpt_lwp_savedname;
+ lwp_unlock(curlwp);
}
void
@@ -977,24 +987,22 @@ threadpool_thread(void *arg)
struct threadpool_job *const job = thread->tpt_job;
KASSERT(job != NULL);
- mutex_spin_exit(&pool->tp_lock);
-
- TP_LOG(("%s: running job '%s' on thread %p.\n",
- __func__, job->job_name, thread));
/* Set our lwp name to reflect what job we're doing. */
lwp_lock(curlwp);
- char *const lwp_name = curlwp->l_name;
+ thread->tpt_lwp_savedname = curlwp->l_name;
curlwp->l_name = job->job_name;
lwp_unlock(curlwp);
+ mutex_spin_exit(&pool->tp_lock);
+
+ TP_LOG(("%s: running job '%s' on thread %p.\n",
+ __func__, job->job_name, thread));
+
/* Run the job. */
(*job->job_fn)(job);
- /* Restore our lwp name. */
- lwp_lock(curlwp);
- curlwp->l_name = lwp_name;
- lwp_unlock(curlwp);
+ /* lwp name restored in threadpool_job_done(). */
/* Job is done and its name is unreferenced. Release it. */
threadpool_job_rele(job);
-- thorpej
