On Fri, Jul 9, 2021 at 8:43 AM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>
> Managed device links are deleted by device_del(). However it is possible to
> add a device link to a consumer before device_add(), and then discover an
> error prevents the device from being used. In that case normally references
> to the device would be dropped and the device would be deleted. However the
> device link holds a reference to the device, so the device link and device
> remain indefinitely.
>
> Amend device link removal to accept removal of a link with an
> unregistered consumer device.
>
> To make that work nicely, the devlink_remove_symlinks() function must be
> amended to cope with the absence of the consumer's sysfs presence,
> otherwise sysfs_remove_link() will generate a warning.
>
> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun")
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> ---
> drivers/base/core.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index ea5b85354526..24bacdb315c6 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -562,7 +562,8 @@ static void devlink_remove_symlinks(struct device *dev,
> struct device *con = link->consumer;
> char *buf;
>
> - sysfs_remove_link(&link->link_dev.kobj, "consumer");
> + if (device_is_registered(con))
> + sysfs_remove_link(&link->link_dev.kobj, "consumer");
I think that this is needed regardless of the changes in
device_link_put_kref(), because if somebody decides to delete a
stateless device link before registering the consumer device,
sysfs_remove_link() will still complain, won't it?
> sysfs_remove_link(&link->link_dev.kobj, "supplier");
>
> len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
> @@ -575,8 +576,10 @@ static void devlink_remove_symlinks(struct device *dev,
> return;
> }
>
> - snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
> - sysfs_remove_link(&con->kobj, buf);
> + if (device_is_registered(con)) {
> + snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
> + sysfs_remove_link(&con->kobj, buf);
> + }
And here too, if I'm not mistaken.
So in that case it would be better to put the above changes into a
separate patch and add a Fixes tag to it.
> snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
> sysfs_remove_link(&sup->kobj, buf);
> kfree(buf);
> @@ -885,6 +888,8 @@ static void device_link_put_kref(struct device_link *link)
> {
> if (link->flags & DL_FLAG_STATELESS)
> kref_put(&link->kref, __device_link_del);
> + else if (!device_is_registered(link->consumer))
> + __device_link_del(&link->kref);
> else
> WARN(1, "Unable to drop a managed device link reference\n");
> }
> --
> 2.17.1
>
