* [PATCH] HID: uhid: allocate static minor
@ 2013-09-09 16:33 David Herrmann
2013-09-09 16:51 ` Tom Gundersen
0 siblings, 1 reply; 3+ messages in thread
From: David Herrmann @ 2013-09-09 16:33 UTC (permalink / raw)
To: linux-input
Cc: Tom Gundersen, Kay Sievers, Marcel Holtmann, linux-kernel,
David Herrmann
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(-)
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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] HID: uhid: allocate static minor
2013-09-09 16:33 [PATCH] HID: uhid: allocate static minor David Herrmann
@ 2013-09-09 16:51 ` Tom Gundersen
2013-09-24 16:28 ` David Herrmann
0 siblings, 1 reply; 3+ messages in thread
From: Tom Gundersen @ 2013-09-09 16:51 UTC (permalink / raw)
To: David Herrmann
Cc: linux-input@vger.kernel.org, Kay Sievers, Marcel Holtmann, LKML
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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] HID: uhid: allocate static minor
2013-09-09 16:51 ` Tom Gundersen
@ 2013-09-24 16:28 ` David Herrmann
0 siblings, 0 replies; 3+ messages in thread
From: David Herrmann @ 2013-09-24 16:28 UTC (permalink / raw)
To: Tom Gundersen
Cc: linux-input@vger.kernel.org, Kay Sievers, Marcel Holtmann, LKML,
Jiri Kosina
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
>>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-09-09 16:51 ` Tom Gundersen
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