Paul Durrant (2):
xen/xenbus: reference count registered modules
xen-blkback: allow module to be cleanly unloaded
drivers/block/xen-blkback/blkback.c | 8 ++++++++
drivers/block/xen-blkback/common.h | 3 +++
drivers/block/xen-blkback/xenbus.c | 11 +++++++++++
drivers/xen/xenbus/xenbus_probe.c | 13 ++++++++++++-
4 files changed, 34 insertions(+), 1 deletion(-)
--
2.20.1
To prevent a PV driver module being removed whilst attached to its other
end, and hence xenbus calling into potentially invalid text, take a
reference on the module before calling the probe() method (dropping it if
unsuccessful) and drop the reference after returning from the remove()
method.
Suggested-by: Jan Beulich <[email protected]>
Signed-off-by: Paul Durrant <[email protected]>
---
Cc: Boris Ostrovsky <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Stefano Stabellini <[email protected]>
v2:
- New in v2
v3:
- Use try_module_get() rather than __module)get() and handle failure
- Not added Juergen's R-b because of the change
---
drivers/xen/xenbus/xenbus_probe.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 5b471889d723..4461f4583476 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -232,9 +232,16 @@ int xenbus_dev_probe(struct device *_dev)
return err;
}
+ if (!try_module_get(drv->driver.owner)) {
+ dev_warn(&dev->dev, "failed to acquire module reference on '%s'.\n",
+ drv->driver.name);
+ err = -ESRCH;
+ goto fail;
+ }
+
err = drv->probe(dev, id);
if (err)
- goto fail;
+ goto fail_put;
err = watch_otherend(dev);
if (err) {
@@ -244,6 +251,8 @@ int xenbus_dev_probe(struct device *_dev)
}
return 0;
+fail_put:
+ module_put(drv->driver.owner);
fail:
xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename);
xenbus_switch_state(dev, XenbusStateClosed);
@@ -263,6 +272,8 @@ int xenbus_dev_remove(struct device *_dev)
if (drv->remove)
drv->remove(dev);
+ module_put(drv->driver.owner);
+
free_otherend_details(dev);
xenbus_switch_state(dev, XenbusStateClosed);
--
2.20.1
Add a module_exit() to perform the necessary clean-up.
Signed-off-by: Paul Durrant <[email protected]>
Reviewed-by: "Roger Pau Monné" <[email protected]>
Reviewed-by: Juergen Gross <[email protected]>
---
Cc: Konrad Rzeszutek Wilk <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Paul Durrant <[email protected]>
---
drivers/block/xen-blkback/blkback.c | 8 ++++++++
drivers/block/xen-blkback/common.h | 3 +++
drivers/block/xen-blkback/xenbus.c | 11 +++++++++++
3 files changed, 22 insertions(+)
diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index fd1e19f1a49f..e562a7e20c3c 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -1504,5 +1504,13 @@ static int __init xen_blkif_init(void)
module_init(xen_blkif_init);
+static void __exit xen_blkif_fini(void)
+{
+ xen_blkif_xenbus_fini();
+ xen_blkif_interface_fini();
+}
+
+module_exit(xen_blkif_fini);
+
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("xen-backend:vbd");
diff --git a/drivers/block/xen-blkback/common.h b/drivers/block/xen-blkback/common.h
index 1d3002d773f7..49132b0adbbe 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -375,9 +375,12 @@ struct phys_req {
struct block_device *bdev;
blkif_sector_t sector_number;
};
+
int xen_blkif_interface_init(void);
+void xen_blkif_interface_fini(void);
int xen_blkif_xenbus_init(void);
+void xen_blkif_xenbus_fini(void);
irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
int xen_blkif_schedule(void *arg);
diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index b90dbcd99c03..e8c5c54e1d26 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -333,6 +333,12 @@ int __init xen_blkif_interface_init(void)
return 0;
}
+void xen_blkif_interface_fini(void)
+{
+ kmem_cache_destroy(xen_blkif_cachep);
+ xen_blkif_cachep = NULL;
+}
+
/*
* sysfs interface for VBD I/O requests
*/
@@ -1122,3 +1128,8 @@ int xen_blkif_xenbus_init(void)
{
return xenbus_register_backend(&xen_blkbk_driver);
}
+
+void xen_blkif_xenbus_fini(void)
+{
+ xenbus_unregister_driver(&xen_blkbk_driver);
+}
--
2.20.1
On 02.12.2019 12:41, Paul Durrant wrote:
> To prevent a PV driver module being removed whilst attached to its other
> end, and hence xenbus calling into potentially invalid text, take a
> reference on the module before calling the probe() method (dropping it if
> unsuccessful) and drop the reference after returning from the remove()
> method.
>
> Suggested-by: Jan Beulich <[email protected]>
> Signed-off-by: Paul Durrant <[email protected]>
Reviewed-by: Jan Beulich <[email protected]>
with ...
> --- a/drivers/xen/xenbus/xenbus_probe.c
> +++ b/drivers/xen/xenbus/xenbus_probe.c
> @@ -232,9 +232,16 @@ int xenbus_dev_probe(struct device *_dev)
> return err;
> }
>
> + if (!try_module_get(drv->driver.owner)) {
> + dev_warn(&dev->dev, "failed to acquire module reference on '%s'.\n",
> + drv->driver.name);
... perhaps the full stop dropped here and ...
> + err = -ESRCH;
> + goto fail;
> + }
... (definitely) indentation here changed to use a tab.
Jan
On 02.12.19 12:41, Paul Durrant wrote:
> To prevent a PV driver module being removed whilst attached to its other
> end, and hence xenbus calling into potentially invalid text, take a
> reference on the module before calling the probe() method (dropping it if
> unsuccessful) and drop the reference after returning from the remove()
> method.
>
> Suggested-by: Jan Beulich <[email protected]>
> Signed-off-by: Paul Durrant <[email protected]>
Pushed to xen/tip.git for-linus-5.5b
Juergen
On 02.12.19 12:41, Paul Durrant wrote:
> Add a module_exit() to perform the necessary clean-up.
>
> Signed-off-by: Paul Durrant <[email protected]>
> Reviewed-by: "Roger Pau Monné" <[email protected]>
> Reviewed-by: Juergen Gross <[email protected]>
Pushed to xen/tip.git for-linus-5.5b
Juergen