linux-kernel - [PATCH V3 3/3] vdpa_sim: flush workers on suspend

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Message-Id: <1716218462-84587-4-git-send-email-steven.sistare@oracle.com>
Date: Mon, 20 May 2024 08:21:02 -0700
From: Steve Sistare <steven.sistare@...cle.com>
To: virtualization@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Cc: "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
        Si-Wei Liu <si-wei.liu@...cle.com>,
        Eugenio Perez Martin <eperezma@...hat.com>,
        Xie Yongji <xieyongji@...edance.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Steve Sistare <steven.sistare@...cle.com>
Subject: [PATCH V3 3/3] vdpa_sim: flush workers on suspend

Flush to guarantee no workers are running when suspend returns.
Add a lock to enforce ordering between clearing running, flushing,
and posting new work in vdpasim_kick_vq.  It must be a spin lock
because vdpasim_kick_vq may be reached va eventfd_write.

Signed-off-by: Steve Sistare <steven.sistare@...cle.com>
---
 drivers/vdpa/vdpa_sim/vdpa_sim.c | 16 ++++++++++++++--
 drivers/vdpa/vdpa_sim/vdpa_sim.h |  1 +
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 8ffea8430f95..67ed49d95bf0 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -322,7 +322,7 @@ static u16 vdpasim_get_vq_size(struct vdpa_device *vdpa, u16 idx)
 		return VDPASIM_QUEUE_MAX;
 }
 
-static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
+static void vdpasim_do_kick_vq(struct vdpa_device *vdpa, u16 idx)
 {
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
@@ -337,6 +337,15 @@ static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
 		vdpasim_schedule_work(vdpasim);
 }
 
+static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
+{
+	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+
+	spin_lock(&vdpasim->kick_lock);
+	vdpasim_do_kick_vq(vdpa, idx);
+	spin_unlock(&vdpasim->kick_lock);
+}
+
 static void vdpasim_set_vq_cb(struct vdpa_device *vdpa, u16 idx,
 			      struct vdpa_callback *cb)
 {
@@ -520,8 +529,11 @@ static int vdpasim_suspend(struct vdpa_device *vdpa)
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
 	mutex_lock(&vdpasim->mutex);
+	spin_lock(&vdpasim->kick_lock);
 	vdpasim->running = false;
+	spin_unlock(&vdpasim->kick_lock);
 	mutex_unlock(&vdpasim->mutex);
+	kthread_flush_work(&vdpasim->work);
 
 	return 0;
 }
@@ -537,7 +549,7 @@ static int vdpasim_resume(struct vdpa_device *vdpa)
 	if (vdpasim->pending_kick) {
 		/* Process pending descriptors */
 		for (i = 0; i < vdpasim->dev_attr.nvqs; ++i)
-			vdpasim_kick_vq(vdpa, i);
+			vdpasim_do_kick_vq(vdpa, i);
 
 		vdpasim->pending_kick = false;
 	}
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
index bb137e479763..5eb6ca9c5ec5 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
@@ -75,6 +75,7 @@ struct vdpasim {
 	bool pending_kick;
 	/* spinlock to synchronize iommu table */
 	spinlock_t iommu_lock;
+	spinlock_t kick_lock;
 };
 
 struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *attr,
-- 
2.39.3