Re: [PATCH 1/6] vhost: get rid of vhost_poll_flush() wrapper

From: Stefano Garzarella
Date: Tue Nov 16 2021 - 09:34:03 EST


On Mon, Nov 15, 2021 at 06:29:58PM +0300, Andrey Ryabinin wrote:
vhost_poll_flush() is a simple wrapper around vhost_work_dev_flush().
It gives wrong impression that we are doing some work over vhost_poll,
while in fact it flushes vhost_poll->dev.
It only complicate understanding of the code and leads to mistakes
like flushing the same vhost_dev several times in a row.

Just remove vhost_poll_flush() and call vhost_work_dev_flush() directly.

Signed-off-by: Andrey Ryabinin <arbn@xxxxxxxxxxxxxxx>
---
drivers/vhost/net.c | 4 ++--
drivers/vhost/test.c | 2 +-
drivers/vhost/vhost.c | 12 ++----------
drivers/vhost/vsock.c | 2 +-
4 files changed, 6 insertions(+), 14 deletions(-)

Adding Mike since these changes could be relevant for "[PATCH V4 00/12] vhost: multiple worker support" [1] series.


diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 28ef323882fb..11221f6d11b8 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -1375,8 +1375,8 @@ static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,

static void vhost_net_flush_vq(struct vhost_net *n, int index)
{
- vhost_poll_flush(n->poll + index);
- vhost_poll_flush(&n->vqs[index].vq.poll);
+ vhost_work_dev_flush(n->poll[index].dev);
+ vhost_work_dev_flush(n->vqs[index].vq.poll.dev);
}

static void vhost_net_flush(struct vhost_net *n)
diff --git a/drivers/vhost/test.c b/drivers/vhost/test.c
index a09dedc79f68..1a8ab1d8cb1c 100644
--- a/drivers/vhost/test.c
+++ b/drivers/vhost/test.c
@@ -146,7 +146,7 @@ static void vhost_test_stop(struct vhost_test *n, void **privatep)

static void vhost_test_flush_vq(struct vhost_test *n, int index)
{
- vhost_poll_flush(&n->vqs[index].poll);
+ vhost_work_dev_flush(n->vqs[index].poll.dev);
}

static void vhost_test_flush(struct vhost_test *n)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 59edb5a1ffe2..ca088481da0e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -245,14 +245,6 @@ void vhost_work_dev_flush(struct vhost_dev *dev)
}
EXPORT_SYMBOL_GPL(vhost_work_dev_flush);

-/* Flush any work that has been scheduled. When calling this, don't hold any
- * locks that are also used by the callback. */
-void vhost_poll_flush(struct vhost_poll *poll)
-{
- vhost_work_dev_flush(poll->dev);
-}
-EXPORT_SYMBOL_GPL(vhost_poll_flush);
-

We should remove also the declaration in vhost.h:

--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -45,7 +44,6 @@ void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
__poll_t mask, struct vhost_dev *dev);
int vhost_poll_start(struct vhost_poll *poll, struct file *file);
void vhost_poll_stop(struct vhost_poll *poll);
-void vhost_poll_flush(struct vhost_poll *poll);
void vhost_poll_queue(struct vhost_poll *poll);
void vhost_work_dev_flush(struct vhost_dev *dev);


void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
{
if (!dev->worker)
@@ -663,7 +655,7 @@ void vhost_dev_stop(struct vhost_dev *dev)
for (i = 0; i < dev->nvqs; ++i) {
if (dev->vqs[i]->kick && dev->vqs[i]->handle_kick) {
vhost_poll_stop(&dev->vqs[i]->poll);
- vhost_poll_flush(&dev->vqs[i]->poll);
+ vhost_work_dev_flush(dev->vqs[i]->poll.dev);
}
}
}
@@ -1712,7 +1704,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
mutex_unlock(&vq->mutex);

if (pollstop && vq->handle_kick)
- vhost_poll_flush(&vq->poll);
+ vhost_work_dev_flush(vq->poll.dev);
return r;
}
EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 938aefbc75ec..b0361ebbd695 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -711,7 +711,7 @@ static void vhost_vsock_flush(struct vhost_vsock *vsock)

for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++)
if (vsock->vqs[i].handle_kick)
- vhost_poll_flush(&vsock->vqs[i].poll);
+ vhost_work_dev_flush(vsock->vqs[i].poll.dev);
vhost_work_dev_flush(&vsock->dev);
}

--
2.32.0


The rest LGTM.

Thanks,
Stefano

[1] https://lore.kernel.org/virtualization/20211104190502.7053-1-michael.christie@xxxxxxxxxx/