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[PATCH v5 17/18] xen/pvcalls: implement write

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When the other end notifies us that there is data to be written
(pvcalls_back_conn_event), increment the io and write counters, and
schedule the ioworker.

Implement the write function called by ioworker by reading the data from
the data ring, writing it to the socket by calling inet_sendmsg.

Set out_error on error.

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
---
 drivers/xen/pvcalls-back.c | 74 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 73 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index ccceabd..424dcac 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -179,7 +179,66 @@ static void pvcalls_conn_back_read(void *opaque)
 
 static int pvcalls_conn_back_write(struct sock_mapping *map)
 {
-	return 0;
+	struct pvcalls_data_intf *intf = map->ring;
+	struct pvcalls_data *data = &map->data;
+	struct msghdr msg;
+	struct kvec vec[2];
+	RING_IDX cons, prod, size, array_size;
+	int ret;
+
+	cons = intf->out_cons;
+	prod = intf->out_prod;
+	/* read the indexes before dealing with the data */
+	virt_mb();
+
+	array_size = XEN_FLEX_RING_SIZE(map->ring_order);
+	size = pvcalls_queued(prod, cons, array_size);
+	if (size == 0)
+		return 0;
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_flags |= MSG_DONTWAIT;
+	msg.msg_iter.type = ITER_KVEC|READ;
+	msg.msg_iter.count = size;
+	if (pvcalls_mask(prod, array_size) > pvcalls_mask(cons, array_size)) {
+		vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
+		vec[0].iov_len = size;
+		msg.msg_iter.kvec = vec;
+		msg.msg_iter.nr_segs = 1;
+	} else {
+		vec[0].iov_base = data->out + pvcalls_mask(cons, array_size);
+		vec[0].iov_len = array_size - pvcalls_mask(cons, array_size);
+		vec[1].iov_base = data->out;
+		vec[1].iov_len = size - vec[0].iov_len;
+		msg.msg_iter.kvec = vec;
+		msg.msg_iter.nr_segs = 2;
+	}
+
+	atomic_set(&map->write, 0);
+	ret = inet_sendmsg(map->sock, &msg, size);
+	if (ret == -EAGAIN || (ret >= 0 && ret < size)) {
+		atomic_inc(&map->write);
+		atomic_inc(&map->io);
+	}
+	if (ret == -EAGAIN)
+		return ret;
+
+	/* write the data, then update the indexes */
+	virt_wmb();
+	if (ret < 0) {
+		intf->out_error = ret;
+	} else {
+		intf->out_error = 0;
+		intf->out_cons = cons + ret;
+		prod = intf->out_prod;
+	}
+	/* update the indexes, then notify the other end */
+	virt_wmb();
+	if (prod != cons + ret)
+		atomic_inc(&map->write);
+	notify_remote_via_irq(map->irq);
+
+	return ret;
 }
 
 static void pvcalls_back_ioworker(struct work_struct *work)
@@ -849,6 +908,19 @@ static irqreturn_t pvcalls_back_event(int irq, void *dev_id)
 
 static irqreturn_t pvcalls_back_conn_event(int irq, void *sock_map)
 {
+	struct sock_mapping *map = sock_map;
+	struct pvcalls_ioworker *iow;
+
+	if (map == NULL || map->sock == NULL || map->sock->sk == NULL ||
+		map->sock->sk->sk_user_data != map)
+		return IRQ_HANDLED;
+
+	iow = &map->ioworker;
+
+	atomic_inc(&map->write);
+	atomic_inc(&map->io);
+	queue_work(iow->wq, &iow->register_work);
+
 	return IRQ_HANDLED;
 }
 
-- 
1.9.1

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Thread

[PATCH v5 00/18] introduce the Xen PV Calls backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 17/18] xen/pvcalls: implement write Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 13/18] xen/pvcalls: implement release command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 10/18] xen/pvcalls: implement listen command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 18/18] xen: introduce a Kconfig option to enable the pvcalls backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 11/18] xen/pvcalls: implement accept command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 16/18] xen/pvcalls: implement read Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 15/18] xen/pvcalls: implement the ioworker functions Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 02/18] xen/pvcalls: introduce the pvcalls xenbus backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 12/18] xen/pvcalls: implement poll command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 06/18] xen/pvcalls: handle commands from the frontend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
    Re: [PATCH v5 06/18] xen/pvcalls: handle commands from the frontend Juergen Gross <jgross@suse.com> - 2017-07-03 13:30 +0200
  [PATCH v5 09/18] xen/pvcalls: implement bind command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
  [PATCH v5 01/18] xen: introduce the pvcalls interface header Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
    [PATCH v5 03/18] xen/pvcalls: initialize the module and register the xenbus backend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
    [PATCH v5 07/18] xen/pvcalls: implement socket command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
    [PATCH v5 05/18] xen/pvcalls: connect to a frontend Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
    [PATCH v5 14/18] xen/pvcalls: disconnect and module_exit Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
    [PATCH v5 08/18] xen/pvcalls: implement connect command Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200
    [PATCH v5 04/18] xen/pvcalls: xenbus state handling Stefano Stabellini <sstabellini@kernel.org> - 2017-06-22 21:20 +0200

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