libzpool: set thread names

Arrange for the thread/task name to be set when new threads are created.
This makes them visible in the process table etc.

pthread_setname_np() is generally available in glibc, musl and FreeBSD,
so no test is required.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Sponsored-by: https://despairlabs.com/sponsor/
Closes openzfs#16140
(cherry picked from commit 4429ad9)

Author: robn

include/sys/zfs_context.h

@@ -228,9 +228,9 @@ typedef pthread_t	kthread_t;
 
 #define	thread_create_named(name, stk, stksize, func, arg, len, \
     pp, state, pri)	\
-	zk_thread_create(func, arg, stksize, state)
+	zk_thread_create(name, func, arg, stksize, state)
 #define	thread_create(stk, stksize, func, arg, len, pp, state, pri)	\
-	zk_thread_create(func, arg, stksize, state)
+	zk_thread_create(#func, func, arg, stksize, state)
 #define	thread_exit()	pthread_exit(NULL)
 #define	thread_join(t)	pthread_join((pthread_t)(t), NULL)
 
@@ -246,8 +246,8 @@ extern struct proc p0;
 
 #define	PS_NONE		-1
 
-extern kthread_t *zk_thread_create(void (*func)(void *), void *arg,
-    size_t stksize, int state);
+extern kthread_t *zk_thread_create(const char *name, void (*func)(void *),
+    void *arg, size_t stksize, int state);
 
 #define	issig(why)	(FALSE)
 #define	ISSIG(thr, why)	(FALSE)

lib/libzpool/kernel.c

@@ -92,7 +92,8 @@ zk_thread_wrapper(void *arg)
 }
 
 kthread_t *
-zk_thread_create(void (*func)(void *), void *arg, size_t stksize, int state)
+zk_thread_create(const char *name, void (*func)(void *), void *arg,
+    size_t stksize, int state)
 {
 	pthread_attr_t attr;
 	pthread_t tid;
@@ -140,6 +141,8 @@ zk_thread_create(void (*func)(void *), void *arg, size_t stksize, int state)
 	VERIFY0(pthread_create(&tid, &attr, zk_thread_wrapper, ztw));
 	VERIFY0(pthread_attr_destroy(&attr));
 
+	pthread_setname_np(tid, name);
+
 	return ((void *)(uintptr_t)tid);
 }
 

lib/libzpool/taskq.c

@@ -295,8 +295,8 @@ taskq_create(const char *name, int nthreads, pri_t pri,
 	}
 
 	for (t = 0; t < nthreads; t++)
-		VERIFY((tq->tq_threadlist[t] = thread_create(NULL, 0,
-		    taskq_thread, tq, 0, &p0, TS_RUN, pri)) != NULL);
+		VERIFY((tq->tq_threadlist[t] = thread_create_named(tq->tq_name,
+		    NULL, 0, taskq_thread, tq, 0, &p0, TS_RUN, pri)) != NULL);
 
 	return (tq);
 }