Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Fri, 9 Jul 2021 13:28:49 +0200 | Subject | Re: [PATCH V2 1/2] driver core: Add ability to delete device links of unregistered devices |
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On Fri, Jul 9, 2021 at 8:43 AM Adrian Hunter <adrian.hunter@intel.com> 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@intel.com> > Fixes: b294ff3e34490 ("scsi: ufs: core: Enable power management for wlun") > Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> > --- > 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 >
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