| Message ID | 1378744434-10883-1-git-send-email-dh.herrmann@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Jiri Kosina |
| Headers | show |
On Mon, Sep 9, 2013 at 6:33 PM, David Herrmann <dh.herrmann@gmail.com> wrote: > udev has this nice feature of creating "dead" /dev/<node> device-nodes if > it finds a devnode:<node> modalias. Once the node is accessed, the kernel > automatically loads the module that provides the node. However, this > requires udev to know the major:minor code to use for the node. This > feature was introduced by: > > commit 578454ff7eab61d13a26b568f99a89a2c9edc881 > Author: Kay Sievers <kay.sievers@vrfy.org> > Date: Thu May 20 18:07:20 2010 +0200 > > driver core: add devname module aliases to allow module on-demand auto-loading > > However, uhid uses dynamic minor numbers so this doesn't actually work. We > need to load uhid to know which minor it's going to use. > > Hence, allocate a static minor (just like uinput does) and we're good > to go. > > Reported-by: Tom Gundersen <teg@jklm.no> Thanks, this works (I only tested the creation of the device node, not the actual module loading). > Signed-off-by: David Herrmann <dh.herrmann@gmail.com> > --- > drivers/hid/uhid.c | 3 ++- > include/linux/miscdevice.h | 1 + > 2 files changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c > index 5bf2fb7..93b00d7 100644 > --- a/drivers/hid/uhid.c > +++ b/drivers/hid/uhid.c > @@ -615,7 +615,7 @@ static const struct file_operations uhid_fops = { > > static struct miscdevice uhid_misc = { > .fops = &uhid_fops, > - .minor = MISC_DYNAMIC_MINOR, > + .minor = UHID_MINOR, > .name = UHID_NAME, > }; > > @@ -634,4 +634,5 @@ module_exit(uhid_exit); > MODULE_LICENSE("GPL"); > MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>"); > MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem"); > +MODULE_ALIAS_MISCDEV(UHID_MINOR); > MODULE_ALIAS("devname:" UHID_NAME); > diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h > index 09c2300..cb35835 100644 > --- a/include/linux/miscdevice.h > +++ b/include/linux/miscdevice.h > @@ -45,6 +45,7 @@ > #define MAPPER_CTRL_MINOR 236 > #define LOOP_CTRL_MINOR 237 > #define VHOST_NET_MINOR 238 > +#define UHID_MINOR 239 > #define MISC_DYNAMIC_MINOR 255 > > struct device; > -- > 1.8.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hey Jiri I forgot to put you on CC on the initial patch. Any comments on this? Cheers David On Mon, Sep 9, 2013 at 6:51 PM, Tom Gundersen <teg@jklm.no> wrote: > On Mon, Sep 9, 2013 at 6:33 PM, David Herrmann <dh.herrmann@gmail.com> wrote: >> udev has this nice feature of creating "dead" /dev/<node> device-nodes if >> it finds a devnode:<node> modalias. Once the node is accessed, the kernel >> automatically loads the module that provides the node. However, this >> requires udev to know the major:minor code to use for the node. This >> feature was introduced by: >> >> commit 578454ff7eab61d13a26b568f99a89a2c9edc881 >> Author: Kay Sievers <kay.sievers@vrfy.org> >> Date: Thu May 20 18:07:20 2010 +0200 >> >> driver core: add devname module aliases to allow module on-demand auto-loading >> >> However, uhid uses dynamic minor numbers so this doesn't actually work. We >> need to load uhid to know which minor it's going to use. >> >> Hence, allocate a static minor (just like uinput does) and we're good >> to go. >> >> Reported-by: Tom Gundersen <teg@jklm.no> > > Thanks, this works (I only tested the creation of the device node, not > the actual module loading). > >> Signed-off-by: David Herrmann <dh.herrmann@gmail.com> >> --- >> drivers/hid/uhid.c | 3 ++- >> include/linux/miscdevice.h | 1 + >> 2 files changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c >> index 5bf2fb7..93b00d7 100644 >> --- a/drivers/hid/uhid.c >> +++ b/drivers/hid/uhid.c >> @@ -615,7 +615,7 @@ static const struct file_operations uhid_fops = { >> >> static struct miscdevice uhid_misc = { >> .fops = &uhid_fops, >> - .minor = MISC_DYNAMIC_MINOR, >> + .minor = UHID_MINOR, >> .name = UHID_NAME, >> }; >> >> @@ -634,4 +634,5 @@ module_exit(uhid_exit); >> MODULE_LICENSE("GPL"); >> MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>"); >> MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem"); >> +MODULE_ALIAS_MISCDEV(UHID_MINOR); >> MODULE_ALIAS("devname:" UHID_NAME); >> diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h >> index 09c2300..cb35835 100644 >> --- a/include/linux/miscdevice.h >> +++ b/include/linux/miscdevice.h >> @@ -45,6 +45,7 @@ >> #define MAPPER_CTRL_MINOR 236 >> #define LOOP_CTRL_MINOR 237 >> #define VHOST_NET_MINOR 238 >> +#define UHID_MINOR 239 >> #define MISC_DYNAMIC_MINOR 255 >> >> struct device; >> -- >> 1.8.4 >> -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/hid/uhid.c b/drivers/hid/uhid.c index 5bf2fb7..93b00d7 100644 --- a/drivers/hid/uhid.c +++ b/drivers/hid/uhid.c @@ -615,7 +615,7 @@ static const struct file_operations uhid_fops = { static struct miscdevice uhid_misc = { .fops = &uhid_fops, - .minor = MISC_DYNAMIC_MINOR, + .minor = UHID_MINOR, .name = UHID_NAME, }; @@ -634,4 +634,5 @@ module_exit(uhid_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>"); MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem"); +MODULE_ALIAS_MISCDEV(UHID_MINOR); MODULE_ALIAS("devname:" UHID_NAME); diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h index 09c2300..cb35835 100644 --- a/include/linux/miscdevice.h +++ b/include/linux/miscdevice.h @@ -45,6 +45,7 @@ #define MAPPER_CTRL_MINOR 236 #define LOOP_CTRL_MINOR 237 #define VHOST_NET_MINOR 238 +#define UHID_MINOR 239 #define MISC_DYNAMIC_MINOR 255 struct device;
udev has this nice feature of creating "dead" /dev/<node> device-nodes if it finds a devnode:<node> modalias. Once the node is accessed, the kernel automatically loads the module that provides the node. However, this requires udev to know the major:minor code to use for the node. This feature was introduced by: commit 578454ff7eab61d13a26b568f99a89a2c9edc881 Author: Kay Sievers <kay.sievers@vrfy.org> Date: Thu May 20 18:07:20 2010 +0200 driver core: add devname module aliases to allow module on-demand auto-loading However, uhid uses dynamic minor numbers so this doesn't actually work. We need to load uhid to know which minor it's going to use. Hence, allocate a static minor (just like uinput does) and we're good to go. Reported-by: Tom Gundersen <teg@jklm.no> Signed-off-by: David Herrmann <dh.herrmann@gmail.com> --- drivers/hid/uhid.c | 3 ++- include/linux/miscdevice.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-)