linux-kernel - [PATCH 2/4] xenbus: limit when state is forced to closed

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Message-ID: <20191205140123.3817-3-pdurrant@amazon.com>
Date:   Thu, 5 Dec 2019 14:01:21 +0000
From:   Paul Durrant <pdurrant@...zon.com>
To:     <linux-kernel@...r.kernel.org>, <xen-devel@...ts.xenproject.org>
CC:     Paul Durrant <pdurrant@...zon.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        "Stefano Stabellini" <sstabellini@...nel.org>
Subject: [PATCH 2/4] xenbus: limit when state is forced to closed

Only force state to closed in the case when the toolstack may need to
clean up. This can be detected by checking whether the state in xenstore
has been set to closing prior to device removal.

Signed-off-by: Paul Durrant <pdurrant@...zon.com>
---
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Stefano Stabellini <sstabellini@...nel.org>
---
 drivers/xen/xenbus/xenbus_probe.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index a10311c348b9..c54a53da0106 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -255,7 +255,6 @@ int xenbus_dev_probe(struct device *_dev)
 	module_put(drv->driver.owner);
 fail:
 	xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
-	xenbus_switch_state(dev, XenbusStateClosed);
 	return err;
 }
 EXPORT_SYMBOL_GPL(xenbus_dev_probe);
@@ -264,6 +263,7 @@ int xenbus_dev_remove(struct device *_dev)
 {
 	struct xenbus_device *dev = to_xenbus_device(_dev);
 	struct xenbus_driver *drv = to_xenbus_driver(_dev->driver);
+	enum xenbus_state state;
 
 	DPRINTK("%s", dev->nodename);
 
@@ -276,7 +276,14 @@ int xenbus_dev_remove(struct device *_dev)
 
 	free_otherend_details(dev);
 
-	xenbus_switch_state(dev, XenbusStateClosed);
+	/*
+	 * If the toolstack had force the device state to closing then set
+	 * the state to closed now to allow it to be cleaned up.
+	 */
+	state = xenbus_read_driver_state(dev->nodename);
+	if (state == XenbusStateClosing)
+		xenbus_switch_state(dev, XenbusStateClosed);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xenbus_dev_remove);
-- 
2.20.1