kthread: add kthread_stop_put

Add a kthread_stop_put() helper that stops a thread and puts its task
struct.  Use it to replace the various instances of kthread_stop()
followed by put_task_struct().

Remove the kthread_stop_put() macro in usbip that is similar but doesn't
return the result of kthread_stop().

[agruenba@redhat.com: fix kerneldoc comment]
  Link: https://lkml.kernel.org/r/20230911111730.2565537-1-agruenba@redhat.com
[akpm@linux-foundation.org: document kthread_stop_put()'s argument]
Link: https://lkml.kernel.org/r/20230907234048.2499820-1-agruenba@redhat.com
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/accel/ivpu/ivpu_job.c

@@ -618,6 +618,5 @@ int ivpu_job_done_thread_init(struct ivpu_device *vdev)
 
 void ivpu_job_done_thread_fini(struct ivpu_device *vdev)
 {
-	kthread_stop(vdev->job_done_thread);
+	kthread_stop_put(vdev->job_done_thread);
-	put_task_struct(vdev->job_done_thread);
 }

drivers/dma-buf/st-dma-fence-chain.c

@@ -476,10 +476,9 @@ static int find_race(void *arg)
 	for (i = 0; i < ncpus; i++) {
 		int ret;
 
-		ret = kthread_stop(threads[i]);
+		ret = kthread_stop_put(threads[i]);
 		if (ret && !err)
 			err = ret;
-		put_task_struct(threads[i]);
 	}
 	kfree(threads);
 
@@ -591,8 +590,7 @@ static int wait_forward(void *arg)
 	for (i = 0; i < fc.chain_length; i++)
 		dma_fence_signal(fc.fences[i]);
 
-	err = kthread_stop(tsk);
+	err = kthread_stop_put(tsk);
-	put_task_struct(tsk);
 
 err:
 	fence_chains_fini(&fc);
@@ -621,8 +619,7 @@ static int wait_backward(void *arg)
 	for (i = fc.chain_length; i--; )
 		dma_fence_signal(fc.fences[i]);
 
-	err = kthread_stop(tsk);
+	err = kthread_stop_put(tsk);
-	put_task_struct(tsk);
 
 err:
 	fence_chains_fini(&fc);
@@ -669,8 +666,7 @@ static int wait_random(void *arg)
 	for (i = 0; i < fc.chain_length; i++)
 		dma_fence_signal(fc.fences[i]);
 
-	err = kthread_stop(tsk);
+	err = kthread_stop_put(tsk);
-	put_task_struct(tsk);
 
 err:
 	fence_chains_fini(&fc);

drivers/dma-buf/st-dma-fence.c

@@ -548,11 +548,9 @@ static int race_signal_callback(void *arg)
 		for (i = 0; i < ARRAY_SIZE(t); i++) {
 			int err;
 
-			err = kthread_stop(t[i].task);
+			err = kthread_stop_put(t[i].task);
 			if (err && !ret)
 				ret = err;
-
-			put_task_struct(t[i].task);
 		}
 	}
 

drivers/gpu/drm/i915/gt/selftest_migrate.c

@@ -719,11 +719,9 @@ static int threaded_migrate(struct intel_migrate *migrate,
 		if (IS_ERR_OR_NULL(tsk))
 			continue;
 
-		status = kthread_stop(tsk);
+		status = kthread_stop_put(tsk);
 		if (status && !err)
 			err = status;
-
-		put_task_struct(tsk);
 	}
 
 	kfree(thread);

drivers/net/xen-netback/interface.c

@@ -672,8 +672,7 @@ err:
 static void xenvif_disconnect_queue(struct xenvif_queue *queue)
 {
 	if (queue->task) {
-		kthread_stop(queue->task);
+		kthread_stop_put(queue->task);
-		put_task_struct(queue->task);
 		queue->task = NULL;
 	}
 

drivers/usb/usbip/usbip_common.h

@@ -298,12 +298,6 @@ struct usbip_device {
 	__k;								   \
 })
 
-#define kthread_stop_put(k)		\
-	do {				\
-		kthread_stop(k);	\
-		put_task_struct(k);	\
-	} while (0)
-
 /* usbip_common.c */
 void usbip_dump_urb(struct urb *purb);
 void usbip_dump_header(struct usbip_header *pdu);

fs/gfs2/ops_fstype.c

@@ -1126,8 +1126,7 @@ static int init_threads(struct gfs2_sbd *sdp)
 	return 0;
 
 fail:
-	kthread_stop(sdp->sd_logd_process);
+	kthread_stop_put(sdp->sd_logd_process);
-	put_task_struct(sdp->sd_logd_process);
 	sdp->sd_logd_process = NULL;
 	return error;
 }
@@ -1135,13 +1134,11 @@ fail:
 void gfs2_destroy_threads(struct gfs2_sbd *sdp)
 {
 	if (sdp->sd_logd_process) {
-		kthread_stop(sdp->sd_logd_process);
+		kthread_stop_put(sdp->sd_logd_process);
-		put_task_struct(sdp->sd_logd_process);
 		sdp->sd_logd_process = NULL;
 	}
 	if (sdp->sd_quotad_process) {
-		kthread_stop(sdp->sd_quotad_process);
+		kthread_stop_put(sdp->sd_quotad_process);
-		put_task_struct(sdp->sd_quotad_process);
 		sdp->sd_quotad_process = NULL;
 	}
 }

include/linux/kthread.h

@@ -86,6 +86,7 @@ void free_kthread_struct(struct task_struct *k);
 void kthread_bind(struct task_struct *k, unsigned int cpu);
 void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask);
 int kthread_stop(struct task_struct *k);
+int kthread_stop_put(struct task_struct *k);
 bool kthread_should_stop(void);
 bool kthread_should_park(void);
 bool kthread_should_stop_or_park(void);

kernel/irq/manage.c

@@ -1852,15 +1852,13 @@ out_thread:
 		struct task_struct *t = new->thread;
 
 		new->thread = NULL;
-		kthread_stop(t);
+		kthread_stop_put(t);
-		put_task_struct(t);
 	}
 	if (new->secondary && new->secondary->thread) {
 		struct task_struct *t = new->secondary->thread;
 
 		new->secondary->thread = NULL;
-		kthread_stop(t);
+		kthread_stop_put(t);
-		put_task_struct(t);
 	}
 out_mput:
 	module_put(desc->owner);
@@ -1971,12 +1969,9 @@ static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
 	 * the same bit to a newly requested action.
 	 */
 	if (action->thread) {
-		kthread_stop(action->thread);
+		kthread_stop_put(action->thread);
-		put_task_struct(action->thread);
+		if (action->secondary && action->secondary->thread)
-		if (action->secondary && action->secondary->thread) {
+			kthread_stop_put(action->secondary->thread);
-			kthread_stop(action->secondary->thread);
-			put_task_struct(action->secondary->thread);
-		}
 	}
 
 	/* Last action releases resources */

kernel/kthread.c

@@ -715,6 +715,24 @@ int kthread_stop(struct task_struct *k)
 }
 EXPORT_SYMBOL(kthread_stop);
 
+/**
+ * kthread_stop_put - stop a thread and put its task struct
+ * @k: thread created by kthread_create().
+ *
+ * Stops a thread created by kthread_create() and put its task_struct.
+ * Only use when holding an extra task struct reference obtained by
+ * calling get_task_struct().
+ */
+int kthread_stop_put(struct task_struct *k)
+{
+	int ret;
+
+	ret = kthread_stop(k);
+	put_task_struct(k);
+	return ret;
+}
+EXPORT_SYMBOL(kthread_stop_put);
+
 int kthreadd(void *unused)
 {
 	struct task_struct *tsk = current;

kernel/smpboot.c

@@ -272,8 +272,7 @@ static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)
 		struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu);
 
 		if (tsk) {
-			kthread_stop(tsk);
+			kthread_stop_put(tsk);
-			put_task_struct(tsk);
 			*per_cpu_ptr(ht->store, cpu) = NULL;
 		}
 	}

mm/damon/core.c

@@ -699,8 +699,7 @@ static int __damon_stop(struct damon_ctx *ctx)
 	if (tsk) {
 		get_task_struct(tsk);
 		mutex_unlock(&ctx->kdamond_lock);
-		kthread_stop(tsk);
+		kthread_stop_put(tsk);
-		put_task_struct(tsk);
 		return 0;
 	}
 	mutex_unlock(&ctx->kdamond_lock);

net/core/pktgen.c

@@ -3982,8 +3982,7 @@ static void __net_exit pg_net_exit(struct net *net)
 	list_for_each_safe(q, n, &list) {
 		t = list_entry(q, struct pktgen_thread, th_list);
 		list_del(&t->th_list);
-		kthread_stop(t->tsk);
+		kthread_stop_put(t->tsk);
-		put_task_struct(t->tsk);
 		kfree(t);
 	}