| Message ID | 20210424021631.1972022-1-rajatja@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2,1/2] driver core: Move the "removable" attribute from USB to core | expand |
On Fri, Apr 23, 2021 at 07:16:30PM -0700, Rajat Jain wrote: > Move the "removable" attribute from USB to core in order to allow > it to be supported by other subsystem / buses. Individual buses > that want to support this attribute can opt-in by setting the > supports_removable flag, and then populating the removable property > of the device while enumerating it. The ABI for the attribute remains > unchanged. > > Signed-off-by: Rajat Jain <rajatja@google.com> > --- > v2: Add documentation For the parts affecting the USB core: Acked-by: Alan Stern <stern@rowland.harvard.edu>
On Fri, Apr 23, 2021 at 07:16:30PM -0700, Rajat Jain wrote: > Move the "removable" attribute from USB to core in order to allow > it to be supported by other subsystem / buses. Individual buses > that want to support this attribute can opt-in by setting the > supports_removable flag, and then populating the removable property > of the device while enumerating it. The ABI for the attribute remains > unchanged. Thanks for confirming that the sysfs ABI is unchanged -- it wasn't obvious to me from the doc descriptions below that the "removable" file appears in the exact same place it did before. Wrap above to fill 75 columns. > Signed-off-by: Rajat Jain <rajatja@google.com> Looks reasonable to me. Trivial comments below. Reviewed-by: Bjorn Helgaas <bhelgaas@google.com> > --- > v2: Add documentation > > Documentation/ABI/testing/sysfs-bus-usb | 11 ------ > .../ABI/testing/sysfs-devices-removable | 17 +++++++++ > drivers/base/core.c | 28 +++++++++++++++ > drivers/usb/core/hub.c | 8 ++--- > drivers/usb/core/sysfs.c | 24 ------------- > drivers/usb/core/usb.c | 1 + > include/linux/device.h | 36 +++++++++++++++++++ > include/linux/usb.h | 7 ---- > 8 files changed, 86 insertions(+), 46 deletions(-) > create mode 100644 Documentation/ABI/testing/sysfs-devices-removable > > diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb > index bf2c1968525f..73eb23bc1f34 100644 > --- a/Documentation/ABI/testing/sysfs-bus-usb > +++ b/Documentation/ABI/testing/sysfs-bus-usb > @@ -154,17 +154,6 @@ Description: > files hold a string value (enable or disable) indicating whether > or not USB3 hardware LPM U1 or U2 is enabled for the device. > > -What: /sys/bus/usb/devices/.../removable > -Date: February 2012 > -Contact: Matthew Garrett <mjg@redhat.com> > -Description: > - Some information about whether a given USB device is > - physically fixed to the platform can be inferred from a > - combination of hub descriptor bits and platform-specific data > - such as ACPI. This file will read either "removable" or > - "fixed" if the information is available, and "unknown" > - otherwise. > - > What: /sys/bus/usb/devices/.../ltm_capable > Date: July 2012 > Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com> > diff --git a/Documentation/ABI/testing/sysfs-devices-removable b/Documentation/ABI/testing/sysfs-devices-removable > new file mode 100644 > index 000000000000..e13dddd547b5 > --- /dev/null > +++ b/Documentation/ABI/testing/sysfs-devices-removable > @@ -0,0 +1,17 @@ > +What: /sys/devices/.../removable > +Date: Apr 2021 > +Contact: Matthew Garrett <mjg@redhat.com>, > + Rajat Jain <rajatja@google.com> > +Description: > + Information about whether a given device is physically fixed to > + the platform. This is determined by the device's subsystem in a > + bus / platform specific way. This attribute is only present for s/platform specific/platform-specific/ > + buses that can support determining such information: > + > + "removable": The device is external / removable from the system. > + "fixed": The device is internal / fixed to the system. > + "unknown": The information is unavailable. > + > + Currently this is only supported by USB (which infers the > + information from a combination of hub descriptor bits and > + platform-specific data such as ACPI). > diff --git a/drivers/base/core.c b/drivers/base/core.c > index f29839382f81..b8ae4cc52805 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -2327,6 +2327,25 @@ static ssize_t online_store(struct device *dev, struct device_attribute *attr, > } > static DEVICE_ATTR_RW(online); > > +static ssize_t removable_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + const char *state; > + > + switch (dev->removable) { > + case DEVICE_REMOVABLE: > + state = "removable"; > + break; > + case DEVICE_FIXED: > + state = "fixed"; > + break; > + default: > + state = "unknown"; > + } > + return sprintf(buf, "%s\n", state); Maybe sysfs_emit()? https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/filesystems/sysfs.rst?id=v5.12#n246 Ironically, the example below the admonition to use sysfs_emit() still uses scnprintf() :) > +} > +static DEVICE_ATTR_RO(removable); > + > int device_add_groups(struct device *dev, const struct attribute_group **groups) > { > return sysfs_create_groups(&dev->kobj, groups); > @@ -2504,8 +2523,16 @@ static int device_add_attrs(struct device *dev) > goto err_remove_dev_online; > } > > + if (type && type->supports_removable) { > + error = device_create_file(dev, &dev_attr_removable); > + if (error) > + goto err_remove_dev_waiting_for_supplier; > + } > + > return 0; > > + err_remove_dev_waiting_for_supplier: > + device_remove_file(dev, &dev_attr_waiting_for_supplier); > err_remove_dev_online: > device_remove_file(dev, &dev_attr_online); > err_remove_dev_groups: > @@ -2525,6 +2552,7 @@ static void device_remove_attrs(struct device *dev) > struct class *class = dev->class; > const struct device_type *type = dev->type; > > + device_remove_file(dev, &dev_attr_removable); > device_remove_file(dev, &dev_attr_waiting_for_supplier); > device_remove_file(dev, &dev_attr_online); > device_remove_groups(dev, dev->groups); > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > index 7f71218cc1e5..500e5648de04 100644 > --- a/drivers/usb/core/hub.c > +++ b/drivers/usb/core/hub.c > @@ -2442,11 +2442,11 @@ static void set_usb_port_removable(struct usb_device *udev) > */ > switch (hub->ports[udev->portnum - 1]->connect_type) { > case USB_PORT_CONNECT_TYPE_HOT_PLUG: > - udev->removable = USB_DEVICE_REMOVABLE; > + dev_set_removable(&udev->dev, DEVICE_REMOVABLE); > return; > case USB_PORT_CONNECT_TYPE_HARD_WIRED: > case USB_PORT_NOT_USED: > - udev->removable = USB_DEVICE_FIXED; > + dev_set_removable(&udev->dev, DEVICE_FIXED); > return; > default: > break; > @@ -2471,9 +2471,9 @@ static void set_usb_port_removable(struct usb_device *udev) > } > > if (removable) > - udev->removable = USB_DEVICE_REMOVABLE; > + dev_set_removable(&udev->dev, DEVICE_REMOVABLE); > else > - udev->removable = USB_DEVICE_FIXED; > + dev_set_removable(&udev->dev, DEVICE_FIXED); > > } > > diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c > index d85699bee671..e8ff3afdf7af 100644 > --- a/drivers/usb/core/sysfs.c > +++ b/drivers/usb/core/sysfs.c > @@ -298,29 +298,6 @@ static ssize_t urbnum_show(struct device *dev, struct device_attribute *attr, > } > static DEVICE_ATTR_RO(urbnum); > > -static ssize_t removable_show(struct device *dev, struct device_attribute *attr, > - char *buf) > -{ > - struct usb_device *udev; > - char *state; > - > - udev = to_usb_device(dev); > - > - switch (udev->removable) { > - case USB_DEVICE_REMOVABLE: > - state = "removable"; > - break; > - case USB_DEVICE_FIXED: > - state = "fixed"; > - break; > - default: > - state = "unknown"; > - } > - > - return sprintf(buf, "%s\n", state); > -} > -static DEVICE_ATTR_RO(removable); > - > static ssize_t ltm_capable_show(struct device *dev, > struct device_attribute *attr, char *buf) > { > @@ -825,7 +802,6 @@ static struct attribute *dev_attrs[] = { > &dev_attr_avoid_reset_quirk.attr, > &dev_attr_authorized.attr, > &dev_attr_remove.attr, > - &dev_attr_removable.attr, > &dev_attr_ltm_capable.attr, > #ifdef CONFIG_OF > &dev_attr_devspec.attr, > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > index a566bb494e24..5a0f73a28196 100644 > --- a/drivers/usb/core/usb.c > +++ b/drivers/usb/core/usb.c > @@ -523,6 +523,7 @@ struct device_type usb_device_type = { > #ifdef CONFIG_PM > .pm = &usb_device_pm_ops, > #endif > + .supports_removable = true, > }; > > > diff --git a/include/linux/device.h b/include/linux/device.h > index ba660731bd25..d6442b811607 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -93,6 +93,12 @@ struct device_type { > void (*release)(struct device *dev); > > const struct dev_pm_ops *pm; > + > + /* > + * Determines whether the subsystem supports classifying the devices of > + * this type into removable vs fixed. > + */ Doesn't really match comment style in rest of the file. Seems pretty self-explanatory, maybe doesn't even need a comment, or perhaps a short comment like this: bool supports_removable:1; /* subsystem supplies info */ > + bool supports_removable; Most boolean structure members in this file are bitfields, e.g., "bool offline:1". > }; > > /* interface for exporting device attributes */ > @@ -350,6 +356,19 @@ enum dl_dev_state { > DL_DEV_UNBINDING, > }; > > +/** > + * enum device_removable - Whether the device is removable. The criteria for a > + * device to be classified as removable, is determined by its subsystem or bus. s/removable,/removable/ Or maybe drop the whole "The criteria ..." sentence? Not sure it adds much useful info. > + * @DEVICE_REMOVABLE_UNKNOWN: Device location is Unknown (default). > + * @DEVICE_REMOVABLE: Device is removable by the user. > + * @DEVICE_FIXED: Device is not removable by the user. > + */ > +enum device_removable { > + DEVICE_REMOVABLE_UNKNOWN = 0, > + DEVICE_REMOVABLE, > + DEVICE_FIXED, > +}; > + > /** > * struct dev_links_info - Device data related to device links. > * @suppliers: List of links to supplier devices. > @@ -431,6 +450,9 @@ struct dev_links_info { > * device (i.e. the bus driver that discovered the device). > * @iommu_group: IOMMU group the device belongs to. > * @iommu: Per device generic IOMMU runtime data > + * @removable: Whether the device can be removed from the system. This > + * should be set by the subsystem / bus driver that discovered > + * the device. > * > * @offline_disabled: If set, the device is permanently online. > * @offline: Set after successful invocation of bus type's .offline(). > @@ -541,6 +563,8 @@ struct device { > struct iommu_group *iommu_group; > struct dev_iommu *iommu; > > + enum device_removable removable; > + > bool offline_disabled:1; > bool offline:1; > bool of_node_reused:1; > @@ -778,6 +802,18 @@ static inline bool dev_has_sync_state(struct device *dev) > return false; > } > > +static inline void dev_set_removable(struct device *dev, > + enum device_removable removable) > +{ > + dev->removable = removable; > +} > + > +static inline bool dev_is_removable(struct device *dev) > +{ > + return dev && dev->type && dev->type->supports_removable > + && dev->removable == DEVICE_REMOVABLE; > +} > + > /* > * High level routines for use by the bus drivers > */ > diff --git a/include/linux/usb.h b/include/linux/usb.h > index d6a41841b93e..0bbb9e8b18c7 100644 > --- a/include/linux/usb.h > +++ b/include/linux/usb.h > @@ -473,12 +473,6 @@ struct usb_dev_state; > > struct usb_tt; > > -enum usb_device_removable { > - USB_DEVICE_REMOVABLE_UNKNOWN = 0, > - USB_DEVICE_REMOVABLE, > - USB_DEVICE_FIXED, > -}; > - > enum usb_port_connect_type { > USB_PORT_CONNECT_TYPE_UNKNOWN = 0, > USB_PORT_CONNECT_TYPE_HOT_PLUG, > @@ -701,7 +695,6 @@ struct usb_device { > #endif > struct wusb_dev *wusb_dev; > int slot_id; > - enum usb_device_removable removable; > struct usb2_lpm_parameters l1_params; > struct usb3_lpm_parameters u1_params; > struct usb3_lpm_parameters u2_params; > -- > 2.31.1.498.g6c1eba8ee3d-goog >
Hi Bjorn, Thanks for the review. On Tue, May 11, 2021 at 12:22 PM Bjorn Helgaas <helgaas@kernel.org> wrote: > > On Fri, Apr 23, 2021 at 07:16:30PM -0700, Rajat Jain wrote: > > Move the "removable" attribute from USB to core in order to allow > > it to be supported by other subsystem / buses. Individual buses > > that want to support this attribute can opt-in by setting the > > supports_removable flag, and then populating the removable property > > of the device while enumerating it. The ABI for the attribute remains > > unchanged. > > Thanks for confirming that the sysfs ABI is unchanged -- it wasn't > obvious to me from the doc descriptions below that the "removable" > file appears in the exact same place it did before. Yes, that is correct. > > > Wrap above to fill 75 columns. Will do. > > > > Signed-off-by: Rajat Jain <rajatja@google.com> > > Looks reasonable to me. Trivial comments below. > > Reviewed-by: Bjorn Helgaas <bhelgaas@google.com> > > > --- > > v2: Add documentation > > > > Documentation/ABI/testing/sysfs-bus-usb | 11 ------ > > .../ABI/testing/sysfs-devices-removable | 17 +++++++++ > > drivers/base/core.c | 28 +++++++++++++++ > > drivers/usb/core/hub.c | 8 ++--- > > drivers/usb/core/sysfs.c | 24 ------------- > > drivers/usb/core/usb.c | 1 + > > include/linux/device.h | 36 +++++++++++++++++++ > > include/linux/usb.h | 7 ---- > > 8 files changed, 86 insertions(+), 46 deletions(-) > > create mode 100644 Documentation/ABI/testing/sysfs-devices-removable > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb > > index bf2c1968525f..73eb23bc1f34 100644 > > --- a/Documentation/ABI/testing/sysfs-bus-usb > > +++ b/Documentation/ABI/testing/sysfs-bus-usb > > @@ -154,17 +154,6 @@ Description: > > files hold a string value (enable or disable) indicating whether > > or not USB3 hardware LPM U1 or U2 is enabled for the device. > > > > -What: /sys/bus/usb/devices/.../removable > > -Date: February 2012 > > -Contact: Matthew Garrett <mjg@redhat.com> > > -Description: > > - Some information about whether a given USB device is > > - physically fixed to the platform can be inferred from a > > - combination of hub descriptor bits and platform-specific data > > - such as ACPI. This file will read either "removable" or > > - "fixed" if the information is available, and "unknown" > > - otherwise. > > - > > What: /sys/bus/usb/devices/.../ltm_capable > > Date: July 2012 > > Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com> > > diff --git a/Documentation/ABI/testing/sysfs-devices-removable b/Documentation/ABI/testing/sysfs-devices-removable > > new file mode 100644 > > index 000000000000..e13dddd547b5 > > --- /dev/null > > +++ b/Documentation/ABI/testing/sysfs-devices-removable > > @@ -0,0 +1,17 @@ > > +What: /sys/devices/.../removable > > +Date: Apr 2021 > > +Contact: Matthew Garrett <mjg@redhat.com>, > > + Rajat Jain <rajatja@google.com> > > +Description: > > + Information about whether a given device is physically fixed to > > + the platform. This is determined by the device's subsystem in a > > + bus / platform specific way. This attribute is only present for > > s/platform specific/platform-specific/ Will do. > > > + buses that can support determining such information: > > + > > + "removable": The device is external / removable from the system. > > + "fixed": The device is internal / fixed to the system. > > + "unknown": The information is unavailable. > > + > > + Currently this is only supported by USB (which infers the > > + information from a combination of hub descriptor bits and > > + platform-specific data such as ACPI). > > diff --git a/drivers/base/core.c b/drivers/base/core.c > > index f29839382f81..b8ae4cc52805 100644 > > --- a/drivers/base/core.c > > +++ b/drivers/base/core.c > > @@ -2327,6 +2327,25 @@ static ssize_t online_store(struct device *dev, struct device_attribute *attr, > > } > > static DEVICE_ATTR_RW(online); > > > > +static ssize_t removable_show(struct device *dev, struct device_attribute *attr, > > + char *buf) > > +{ > > + const char *state; > > + > > + switch (dev->removable) { > > + case DEVICE_REMOVABLE: > > + state = "removable"; > > + break; > > + case DEVICE_FIXED: > > + state = "fixed"; > > + break; > > + default: > > + state = "unknown"; > > + } > > + return sprintf(buf, "%s\n", state); > > Maybe sysfs_emit()? > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/filesystems/sysfs.rst?id=v5.12#n246 Will do. > > Ironically, the example below the admonition to use sysfs_emit() still > uses scnprintf() :) > > > +} > > +static DEVICE_ATTR_RO(removable); > > + > > int device_add_groups(struct device *dev, const struct attribute_group **groups) > > { > > return sysfs_create_groups(&dev->kobj, groups); > > @@ -2504,8 +2523,16 @@ static int device_add_attrs(struct device *dev) > > goto err_remove_dev_online; > > } > > > > + if (type && type->supports_removable) { > > + error = device_create_file(dev, &dev_attr_removable); > > + if (error) > > + goto err_remove_dev_waiting_for_supplier; > > + } > > + > > return 0; > > > > + err_remove_dev_waiting_for_supplier: > > + device_remove_file(dev, &dev_attr_waiting_for_supplier); > > err_remove_dev_online: > > device_remove_file(dev, &dev_attr_online); > > err_remove_dev_groups: > > @@ -2525,6 +2552,7 @@ static void device_remove_attrs(struct device *dev) > > struct class *class = dev->class; > > const struct device_type *type = dev->type; > > > > + device_remove_file(dev, &dev_attr_removable); > > device_remove_file(dev, &dev_attr_waiting_for_supplier); > > device_remove_file(dev, &dev_attr_online); > > device_remove_groups(dev, dev->groups); > > diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c > > index 7f71218cc1e5..500e5648de04 100644 > > --- a/drivers/usb/core/hub.c > > +++ b/drivers/usb/core/hub.c > > @@ -2442,11 +2442,11 @@ static void set_usb_port_removable(struct usb_device *udev) > > */ > > switch (hub->ports[udev->portnum - 1]->connect_type) { > > case USB_PORT_CONNECT_TYPE_HOT_PLUG: > > - udev->removable = USB_DEVICE_REMOVABLE; > > + dev_set_removable(&udev->dev, DEVICE_REMOVABLE); > > return; > > case USB_PORT_CONNECT_TYPE_HARD_WIRED: > > case USB_PORT_NOT_USED: > > - udev->removable = USB_DEVICE_FIXED; > > + dev_set_removable(&udev->dev, DEVICE_FIXED); > > return; > > default: > > break; > > @@ -2471,9 +2471,9 @@ static void set_usb_port_removable(struct usb_device *udev) > > } > > > > if (removable) > > - udev->removable = USB_DEVICE_REMOVABLE; > > + dev_set_removable(&udev->dev, DEVICE_REMOVABLE); > > else > > - udev->removable = USB_DEVICE_FIXED; > > + dev_set_removable(&udev->dev, DEVICE_FIXED); > > > > } > > > > diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c > > index d85699bee671..e8ff3afdf7af 100644 > > --- a/drivers/usb/core/sysfs.c > > +++ b/drivers/usb/core/sysfs.c > > @@ -298,29 +298,6 @@ static ssize_t urbnum_show(struct device *dev, struct device_attribute *attr, > > } > > static DEVICE_ATTR_RO(urbnum); > > > > -static ssize_t removable_show(struct device *dev, struct device_attribute *attr, > > - char *buf) > > -{ > > - struct usb_device *udev; > > - char *state; > > - > > - udev = to_usb_device(dev); > > - > > - switch (udev->removable) { > > - case USB_DEVICE_REMOVABLE: > > - state = "removable"; > > - break; > > - case USB_DEVICE_FIXED: > > - state = "fixed"; > > - break; > > - default: > > - state = "unknown"; > > - } > > - > > - return sprintf(buf, "%s\n", state); > > -} > > -static DEVICE_ATTR_RO(removable); > > - > > static ssize_t ltm_capable_show(struct device *dev, > > struct device_attribute *attr, char *buf) > > { > > @@ -825,7 +802,6 @@ static struct attribute *dev_attrs[] = { > > &dev_attr_avoid_reset_quirk.attr, > > &dev_attr_authorized.attr, > > &dev_attr_remove.attr, > > - &dev_attr_removable.attr, > > &dev_attr_ltm_capable.attr, > > #ifdef CONFIG_OF > > &dev_attr_devspec.attr, > > diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c > > index a566bb494e24..5a0f73a28196 100644 > > --- a/drivers/usb/core/usb.c > > +++ b/drivers/usb/core/usb.c > > @@ -523,6 +523,7 @@ struct device_type usb_device_type = { > > #ifdef CONFIG_PM > > .pm = &usb_device_pm_ops, > > #endif > > + .supports_removable = true, > > }; > > > > > > diff --git a/include/linux/device.h b/include/linux/device.h > > index ba660731bd25..d6442b811607 100644 > > --- a/include/linux/device.h > > +++ b/include/linux/device.h > > @@ -93,6 +93,12 @@ struct device_type { > > void (*release)(struct device *dev); > > > > const struct dev_pm_ops *pm; > > + > > + /* > > + * Determines whether the subsystem supports classifying the devices of > > + * this type into removable vs fixed. > > + */ > > Doesn't really match comment style in rest of the file. Seems pretty > self-explanatory, maybe doesn't even need a comment, or perhaps a > short comment like this: > > bool supports_removable:1; /* subsystem supplies info */ > > > + bool supports_removable; Will do. > > Most boolean structure members in this file are bitfields, e.g., > "bool offline:1". Will do. > > > }; > > > > /* interface for exporting device attributes */ > > @@ -350,6 +356,19 @@ enum dl_dev_state { > > DL_DEV_UNBINDING, > > }; > > > > +/** > > + * enum device_removable - Whether the device is removable. The criteria for a > > + * device to be classified as removable, is determined by its subsystem or bus. > > s/removable,/removable/ Will do. > > Or maybe drop the whole "The criteria ..." sentence? Not sure it adds > much useful info. I'd prefer to keep the comment because I feel it makes it clear that different buses may employ different criteria to decide what classifies as "removable" vs "fixed". Thanks, Rajat > > > + * @DEVICE_REMOVABLE_UNKNOWN: Device location is Unknown (default). > > + * @DEVICE_REMOVABLE: Device is removable by the user. > > + * @DEVICE_FIXED: Device is not removable by the user. > > + */ > > +enum device_removable { > > + DEVICE_REMOVABLE_UNKNOWN = 0, > > + DEVICE_REMOVABLE, > > + DEVICE_FIXED, > > +}; > > + > > /** > > * struct dev_links_info - Device data related to device links. > > * @suppliers: List of links to supplier devices. > > @@ -431,6 +450,9 @@ struct dev_links_info { > > * device (i.e. the bus driver that discovered the device). > > * @iommu_group: IOMMU group the device belongs to. > > * @iommu: Per device generic IOMMU runtime data > > + * @removable: Whether the device can be removed from the system. This > > + * should be set by the subsystem / bus driver that discovered > > + * the device. > > * > > * @offline_disabled: If set, the device is permanently online. > > * @offline: Set after successful invocation of bus type's .offline(). > > @@ -541,6 +563,8 @@ struct device { > > struct iommu_group *iommu_group; > > struct dev_iommu *iommu; > > > > + enum device_removable removable; > > + > > bool offline_disabled:1; > > bool offline:1; > > bool of_node_reused:1; > > @@ -778,6 +802,18 @@ static inline bool dev_has_sync_state(struct device *dev) > > return false; > > } > > > > +static inline void dev_set_removable(struct device *dev, > > + enum device_removable removable) > > +{ > > + dev->removable = removable; > > +} > > + > > +static inline bool dev_is_removable(struct device *dev) > > +{ > > + return dev && dev->type && dev->type->supports_removable > > + && dev->removable == DEVICE_REMOVABLE; > > +} > > + > > /* > > * High level routines for use by the bus drivers > > */ > > diff --git a/include/linux/usb.h b/include/linux/usb.h > > index d6a41841b93e..0bbb9e8b18c7 100644 > > --- a/include/linux/usb.h > > +++ b/include/linux/usb.h > > @@ -473,12 +473,6 @@ struct usb_dev_state; > > > > struct usb_tt; > > > > -enum usb_device_removable { > > - USB_DEVICE_REMOVABLE_UNKNOWN = 0, > > - USB_DEVICE_REMOVABLE, > > - USB_DEVICE_FIXED, > > -}; > > - > > enum usb_port_connect_type { > > USB_PORT_CONNECT_TYPE_UNKNOWN = 0, > > USB_PORT_CONNECT_TYPE_HOT_PLUG, > > @@ -701,7 +695,6 @@ struct usb_device { > > #endif > > struct wusb_dev *wusb_dev; > > int slot_id; > > - enum usb_device_removable removable; > > struct usb2_lpm_parameters l1_params; > > struct usb3_lpm_parameters u1_params; > > struct usb3_lpm_parameters u2_params; > > -- > > 2.31.1.498.g6c1eba8ee3d-goog > >
Hi Rajat, I have few questions below, but to add in advance, I might be confusing the role that "type->supports_removable" and "dev->removable" plays here, and if so then I apologise. [...] > @@ -2504,8 +2523,16 @@ static int device_add_attrs(struct device *dev) > goto err_remove_dev_online; > } > > + if (type && type->supports_removable) { > + error = device_create_file(dev, &dev_attr_removable); > + if (error) > + goto err_remove_dev_waiting_for_supplier; > + } > + > return 0; Would a check for "dev->removable == DEVICE_REMOVABLE" here be more appropriate? Unless you wanted to add sysfs objects when the device hints that it has a notion of being removable even though it might be set to "unknown" or "fixed" (if that state is at all possible then), and in which case using the dev_is_removable() helper would also not be an option since it does a more complex check internally. Technically, you could always add this sysfs object (similarly to what USB core did) as it would then show the correct state depending on "dev->removable". Also, I suppose, it's not possible for a device to have "supports_removable" set to true, but "removable" would be different than "DEVICE_REMOVABLE", correct? [...] > +enum device_removable { > + DEVICE_REMOVABLE_UNKNOWN = 0, > + DEVICE_REMOVABLE, > + DEVICE_FIXED, > +}; I know this was moved from the USB core, but I personally find it a little bit awkward to read, would something like that be acceptable? enum device_removable { DEVICE_STATE_UNKNOWN = 0, DEVICE_STATE_REMOVABLE, DEVICE_STATE_FIXED, }; The addition of state to the name follows the removable_show() function where the local variable is called "state", and I think it makes sense to call this as such. What do you think? > +static inline bool dev_is_removable(struct device *dev) > +{ > + return dev && dev->type && dev->type->supports_removable > + && dev->removable == DEVICE_REMOVABLE; > +} Similarly to my question about - would a simple check to see if "dev->removable" is set to "DEVICE_REMOVABLE" here be enough? Krzysztof
Hi Krzysztof, Thanks a lot for your comments. Please see inline. On Tue, May 11, 2021 at 6:00 PM Krzysztof Wilczyński <kw@linux.com> wrote: > > Hi Rajat, > > I have few questions below, but to add in advance, I might be confusing > the role that "type->supports_removable" and "dev->removable" plays > here, and if so then I apologise. > > [...] > > @@ -2504,8 +2523,16 @@ static int device_add_attrs(struct device *dev) > > goto err_remove_dev_online; > > } > > > > + if (type && type->supports_removable) { > > + error = device_create_file(dev, &dev_attr_removable); > > + if (error) > > + goto err_remove_dev_waiting_for_supplier; > > + } > > + > > return 0; > > Would a check for "dev->removable == DEVICE_REMOVABLE" here be more > appropriate? > > Unless you wanted to add sysfs objects when the device hints that it has > a notion of being removable even though it might be set to "unknown" or > "fixed" (if that state is at all possible then), and in which case using > the dev_is_removable() helper would also not be an option since it does > a more complex check internally. > > Technically, you could always add this sysfs object (similarly to what > USB core did) as it would then show the correct state depending on > "dev->removable". > > Also, I suppose, it's not possible for a device to have > "supports_removable" set to true, but "removable" would be different > than "DEVICE_REMOVABLE", correct? No, that is not true. device_type->supports_removable=1 indicates that the bus / subsystem is capable of differentiating between removable and fixed devices. It's essentially describing a capability of the bus / subsystem. This flag needs to be true for a subsystem for any it's devices' dev->removable field to be considered meaningful. OTOH, the dev->removable => indicates the location of the device IF device_type->supports location is true. Yes, it can be fixed / removable / unknown (whatever the bus decides) if the device_type->supports_location is true. One of my primary considerations was also that the existing UAPI for the USB's "removable" attribute shouldn't be changed. Currently, it exists for all USB devices, so I think the current code / check is OK. > > [...] > > +enum device_removable { > > + DEVICE_REMOVABLE_UNKNOWN = 0, > > + DEVICE_REMOVABLE, > > + DEVICE_FIXED, > > +}; > > I know this was moved from the USB core, but I personally find it > a little bit awkward to read, would something like that be acceptable? > > enum device_removable { > DEVICE_STATE_UNKNOWN = 0, > DEVICE_STATE_REMOVABLE, > DEVICE_STATE_FIXED, > }; > > The addition of state to the name follows the removable_show() function > where the local variable is called "state", and I think it makes sense > to call this as such. What do you think? I think I made a mistake by using the "state" as the local variable there. I will change it to "location". I'm happy to change the enums above to DEVICE_LOCATION_REMOVABLE* etc if there is a wider consensus on this. IMHO, the current shorter one also looks OK. > > > +static inline bool dev_is_removable(struct device *dev) > > +{ > > + return dev && dev->type && dev->type->supports_removable > > + && dev->removable == DEVICE_REMOVABLE; > > +} > > Similarly to my question about - would a simple check to see if > "dev->removable" is set to "DEVICE_REMOVABLE" here be enough? No, as I mentioned above, the dev->removable field should be considered meaningful only if device_type->supports_location is true. So the check for supports_removable is needed here. Please feel free to send me more thoughts. Thanks & Best Regards, Rajat > > Krzysztof
Posted a v3 of this patch here: https://lore.kernel.org/patchwork/patch/1428133/ On Tue, May 11, 2021 at 6:21 PM Rajat Jain <rajatxjain@gmail.com> wrote: > > Hi Krzysztof, > > Thanks a lot for your comments. Please see inline. > > On Tue, May 11, 2021 at 6:00 PM Krzysztof Wilczyński <kw@linux.com> wrote: > > > > Hi Rajat, > > > > I have few questions below, but to add in advance, I might be confusing > > the role that "type->supports_removable" and "dev->removable" plays > > here, and if so then I apologise. > > > > [...] > > > @@ -2504,8 +2523,16 @@ static int device_add_attrs(struct device *dev) > > > goto err_remove_dev_online; > > > } > > > > > > + if (type && type->supports_removable) { > > > + error = device_create_file(dev, &dev_attr_removable); > > > + if (error) > > > + goto err_remove_dev_waiting_for_supplier; > > > + } > > > + > > > return 0; > > > > Would a check for "dev->removable == DEVICE_REMOVABLE" here be more > > appropriate? > > > > Unless you wanted to add sysfs objects when the device hints that it has > > a notion of being removable even though it might be set to "unknown" or > > "fixed" (if that state is at all possible then), and in which case using > > the dev_is_removable() helper would also not be an option since it does > > a more complex check internally. > > > > Technically, you could always add this sysfs object (similarly to what > > USB core did) as it would then show the correct state depending on > > "dev->removable". > > > > Also, I suppose, it's not possible for a device to have > > "supports_removable" set to true, but "removable" would be different > > than "DEVICE_REMOVABLE", correct? > > No, that is not true. > > device_type->supports_removable=1 indicates that the bus / subsystem > is capable of differentiating between removable and fixed devices. > It's essentially describing a capability of the bus / subsystem. This > flag needs to be true for a subsystem for any it's devices' > dev->removable field to be considered meaningful. > > OTOH, the dev->removable => indicates the location of the device IF > device_type->supports location is true. Yes, it can be fixed / > removable / unknown (whatever the bus decides) if the > device_type->supports_location is true. > > One of my primary considerations was also that the existing UAPI for > the USB's "removable" attribute shouldn't be changed. Currently, it > exists for all USB devices, so I think the current code / check is OK. > > > > > [...] > > > +enum device_removable { > > > + DEVICE_REMOVABLE_UNKNOWN = 0, > > > + DEVICE_REMOVABLE, > > > + DEVICE_FIXED, > > > +}; > > > > I know this was moved from the USB core, but I personally find it > > a little bit awkward to read, would something like that be acceptable? > > > > enum device_removable { > > DEVICE_STATE_UNKNOWN = 0, > > DEVICE_STATE_REMOVABLE, > > DEVICE_STATE_FIXED, > > }; > > > > The addition of state to the name follows the removable_show() function > > where the local variable is called "state", and I think it makes sense > > to call this as such. What do you think? > > I think I made a mistake by using the "state" as the local variable > there. I will change it to "location". I'm happy to change the enums > above to DEVICE_LOCATION_REMOVABLE* etc if there is a wider consensus > on this. IMHO, the current shorter one also looks OK. > > > > > > +static inline bool dev_is_removable(struct device *dev) > > > +{ > > > + return dev && dev->type && dev->type->supports_removable > > > + && dev->removable == DEVICE_REMOVABLE; > > > +} > > > > Similarly to my question about - would a simple check to see if > > "dev->removable" is set to "DEVICE_REMOVABLE" here be enough? > > No, as I mentioned above, the dev->removable field should be > considered meaningful only if device_type->supports_location is true. > So the check for supports_removable is needed here. > > Please feel free to send me more thoughts. > > Thanks & Best Regards, > > Rajat > > > > > > Krzysztof
Hi Rajat, > Posted a v3 of this patch here: > https://lore.kernel.org/patchwork/patch/1428133/ I saw! Thank you! I also found the original conversation around the main idea that's driving the work done here, as per: https://lore.kernel.org/lkml/20200601232542.GA473883@bjorn-Precision-5520/ This helped to fill-in some missing pieces, so to speak, I've bad. [...] > > > > @@ -2504,8 +2523,16 @@ static int device_add_attrs(struct device *dev) > > > > goto err_remove_dev_online; > > > > } > > > > > > > > + if (type && type->supports_removable) { > > > > + error = device_create_file(dev, &dev_attr_removable); > > > > + if (error) > > > > + goto err_remove_dev_waiting_for_supplier; > > > > + } > > > > + > > > > return 0; > > > > > One of my primary considerations was also that the existing UAPI for > > the USB's "removable" attribute shouldn't be changed. Currently, it > > exists for all USB devices, so I think the current code / check is OK. [...] We wouldn't change addition of this attribute to the USB devices - after the lift to the device core it still has to work as before, as you say. Just to clarify. What I was wondering is whether we should add this new sysfs object so that every device now would get this attribute going forward, regardless of whether it would have the "type->supports_removable" set. We would then have a lot of devices with this attribute set to "unknown", and then were the is an actual support it would then be either "fixed" or "removable". Having said that, Bjorn pointed out to me that this might be not necessarily desirable. We were also wondering if we should only set DEVICE_REMOVABLE for devices known to be behind an external-facing port, and let everything else be set to "unknown" (or whatever the default would be). Krzysztof
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index bf2c1968525f..73eb23bc1f34 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -154,17 +154,6 @@ Description: files hold a string value (enable or disable) indicating whether or not USB3 hardware LPM U1 or U2 is enabled for the device. -What: /sys/bus/usb/devices/.../removable -Date: February 2012 -Contact: Matthew Garrett <mjg@redhat.com> -Description: - Some information about whether a given USB device is - physically fixed to the platform can be inferred from a - combination of hub descriptor bits and platform-specific data - such as ACPI. This file will read either "removable" or - "fixed" if the information is available, and "unknown" - otherwise. - What: /sys/bus/usb/devices/.../ltm_capable Date: July 2012 Contact: Sarah Sharp <sarah.a.sharp@linux.intel.com> diff --git a/Documentation/ABI/testing/sysfs-devices-removable b/Documentation/ABI/testing/sysfs-devices-removable new file mode 100644 index 000000000000..e13dddd547b5 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-devices-removable @@ -0,0 +1,17 @@ +What: /sys/devices/.../removable +Date: Apr 2021 +Contact: Matthew Garrett <mjg@redhat.com>, + Rajat Jain <rajatja@google.com> +Description: + Information about whether a given device is physically fixed to + the platform. This is determined by the device's subsystem in a + bus / platform specific way. This attribute is only present for + buses that can support determining such information: + + "removable": The device is external / removable from the system. + "fixed": The device is internal / fixed to the system. + "unknown": The information is unavailable. + + Currently this is only supported by USB (which infers the + information from a combination of hub descriptor bits and + platform-specific data such as ACPI). diff --git a/drivers/base/core.c b/drivers/base/core.c index f29839382f81..b8ae4cc52805 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2327,6 +2327,25 @@ static ssize_t online_store(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RW(online); +static ssize_t removable_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + const char *state; + + switch (dev->removable) { + case DEVICE_REMOVABLE: + state = "removable"; + break; + case DEVICE_FIXED: + state = "fixed"; + break; + default: + state = "unknown"; + } + return sprintf(buf, "%s\n", state); +} +static DEVICE_ATTR_RO(removable); + int device_add_groups(struct device *dev, const struct attribute_group **groups) { return sysfs_create_groups(&dev->kobj, groups); @@ -2504,8 +2523,16 @@ static int device_add_attrs(struct device *dev) goto err_remove_dev_online; } + if (type && type->supports_removable) { + error = device_create_file(dev, &dev_attr_removable); + if (error) + goto err_remove_dev_waiting_for_supplier; + } + return 0; + err_remove_dev_waiting_for_supplier: + device_remove_file(dev, &dev_attr_waiting_for_supplier); err_remove_dev_online: device_remove_file(dev, &dev_attr_online); err_remove_dev_groups: @@ -2525,6 +2552,7 @@ static void device_remove_attrs(struct device *dev) struct class *class = dev->class; const struct device_type *type = dev->type; + device_remove_file(dev, &dev_attr_removable); device_remove_file(dev, &dev_attr_waiting_for_supplier); device_remove_file(dev, &dev_attr_online); device_remove_groups(dev, dev->groups); diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 7f71218cc1e5..500e5648de04 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2442,11 +2442,11 @@ static void set_usb_port_removable(struct usb_device *udev) */ switch (hub->ports[udev->portnum - 1]->connect_type) { case USB_PORT_CONNECT_TYPE_HOT_PLUG: - udev->removable = USB_DEVICE_REMOVABLE; + dev_set_removable(&udev->dev, DEVICE_REMOVABLE); return; case USB_PORT_CONNECT_TYPE_HARD_WIRED: case USB_PORT_NOT_USED: - udev->removable = USB_DEVICE_FIXED; + dev_set_removable(&udev->dev, DEVICE_FIXED); return; default: break; @@ -2471,9 +2471,9 @@ static void set_usb_port_removable(struct usb_device *udev) } if (removable) - udev->removable = USB_DEVICE_REMOVABLE; + dev_set_removable(&udev->dev, DEVICE_REMOVABLE); else - udev->removable = USB_DEVICE_FIXED; + dev_set_removable(&udev->dev, DEVICE_FIXED); } diff --git a/drivers/usb/core/sysfs.c b/drivers/usb/core/sysfs.c index d85699bee671..e8ff3afdf7af 100644 --- a/drivers/usb/core/sysfs.c +++ b/drivers/usb/core/sysfs.c @@ -298,29 +298,6 @@ static ssize_t urbnum_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(urbnum); -static ssize_t removable_show(struct device *dev, struct device_attribute *attr, - char *buf) -{ - struct usb_device *udev; - char *state; - - udev = to_usb_device(dev); - - switch (udev->removable) { - case USB_DEVICE_REMOVABLE: - state = "removable"; - break; - case USB_DEVICE_FIXED: - state = "fixed"; - break; - default: - state = "unknown"; - } - - return sprintf(buf, "%s\n", state); -} -static DEVICE_ATTR_RO(removable); - static ssize_t ltm_capable_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -825,7 +802,6 @@ static struct attribute *dev_attrs[] = { &dev_attr_avoid_reset_quirk.attr, &dev_attr_authorized.attr, &dev_attr_remove.attr, - &dev_attr_removable.attr, &dev_attr_ltm_capable.attr, #ifdef CONFIG_OF &dev_attr_devspec.attr, diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c index a566bb494e24..5a0f73a28196 100644 --- a/drivers/usb/core/usb.c +++ b/drivers/usb/core/usb.c @@ -523,6 +523,7 @@ struct device_type usb_device_type = { #ifdef CONFIG_PM .pm = &usb_device_pm_ops, #endif + .supports_removable = true, }; diff --git a/include/linux/device.h b/include/linux/device.h index ba660731bd25..d6442b811607 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -93,6 +93,12 @@ struct device_type { void (*release)(struct device *dev); const struct dev_pm_ops *pm; + + /* + * Determines whether the subsystem supports classifying the devices of + * this type into removable vs fixed. + */ + bool supports_removable; }; /* interface for exporting device attributes */ @@ -350,6 +356,19 @@ enum dl_dev_state { DL_DEV_UNBINDING, }; +/** + * enum device_removable - Whether the device is removable. The criteria for a + * device to be classified as removable, is determined by its subsystem or bus. + * @DEVICE_REMOVABLE_UNKNOWN: Device location is Unknown (default). + * @DEVICE_REMOVABLE: Device is removable by the user. + * @DEVICE_FIXED: Device is not removable by the user. + */ +enum device_removable { + DEVICE_REMOVABLE_UNKNOWN = 0, + DEVICE_REMOVABLE, + DEVICE_FIXED, +}; + /** * struct dev_links_info - Device data related to device links. * @suppliers: List of links to supplier devices. @@ -431,6 +450,9 @@ struct dev_links_info { * device (i.e. the bus driver that discovered the device). * @iommu_group: IOMMU group the device belongs to. * @iommu: Per device generic IOMMU runtime data + * @removable: Whether the device can be removed from the system. This + * should be set by the subsystem / bus driver that discovered + * the device. * * @offline_disabled: If set, the device is permanently online. * @offline: Set after successful invocation of bus type's .offline(). @@ -541,6 +563,8 @@ struct device { struct iommu_group *iommu_group; struct dev_iommu *iommu; + enum device_removable removable; + bool offline_disabled:1; bool offline:1; bool of_node_reused:1; @@ -778,6 +802,18 @@ static inline bool dev_has_sync_state(struct device *dev) return false; } +static inline void dev_set_removable(struct device *dev, + enum device_removable removable) +{ + dev->removable = removable; +} + +static inline bool dev_is_removable(struct device *dev) +{ + return dev && dev->type && dev->type->supports_removable + && dev->removable == DEVICE_REMOVABLE; +} + /* * High level routines for use by the bus drivers */ diff --git a/include/linux/usb.h b/include/linux/usb.h index d6a41841b93e..0bbb9e8b18c7 100644 --- a/include/linux/usb.h +++ b/include/linux/usb.h @@ -473,12 +473,6 @@ struct usb_dev_state; struct usb_tt; -enum usb_device_removable { - USB_DEVICE_REMOVABLE_UNKNOWN = 0, - USB_DEVICE_REMOVABLE, - USB_DEVICE_FIXED, -}; - enum usb_port_connect_type { USB_PORT_CONNECT_TYPE_UNKNOWN = 0, USB_PORT_CONNECT_TYPE_HOT_PLUG, @@ -701,7 +695,6 @@ struct usb_device { #endif struct wusb_dev *wusb_dev; int slot_id; - enum usb_device_removable removable; struct usb2_lpm_parameters l1_params; struct usb3_lpm_parameters u1_params; struct usb3_lpm_parameters u2_params;
Move the "removable" attribute from USB to core in order to allow it to be supported by other subsystem / buses. Individual buses that want to support this attribute can opt-in by setting the supports_removable flag, and then populating the removable property of the device while enumerating it. The ABI for the attribute remains unchanged. Signed-off-by: Rajat Jain <rajatja@google.com> --- v2: Add documentation Documentation/ABI/testing/sysfs-bus-usb | 11 ------ .../ABI/testing/sysfs-devices-removable | 17 +++++++++ drivers/base/core.c | 28 +++++++++++++++ drivers/usb/core/hub.c | 8 ++--- drivers/usb/core/sysfs.c | 24 ------------- drivers/usb/core/usb.c | 1 + include/linux/device.h | 36 +++++++++++++++++++ include/linux/usb.h | 7 ---- 8 files changed, 86 insertions(+), 46 deletions(-) create mode 100644 Documentation/ABI/testing/sysfs-devices-removable