Re: [PATCH 06/24] tools headers uapi: Sync linux/usbdevice_fs.h with the kernel sources

[Alan Stern]

On Tue, 1 Oct 2019, Arnaldo Carvalho de Melo wrote:

> From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> 
> To pick up the changes from:
> 
>   4ed3350539aa ("USB: usbfs: Add a capability flag for runtime suspend")
>   7794f486ed0b ("usbfs: Add ioctls for runtime power management")
> 
> This triggers these changes in the kernel sources, automagically
> supporting these new ioctls in the 'perf trace' beautifiers.
> 
> Soon this will be used in things like filter expressions for tracepoints
> in 'perf record', 'perf trace', 'perf top', i.e. filter expressions will
> do a lookup to turn things like USBDEVFS_WAIT_FOR_RESUME into _IO('U',
> 35) before associating the tracepoint expression to tracepoint perf
> event.
> 
>   $ tools/perf/trace/beauty/usbdevfs_ioctl.sh  > before
>   $ cp include/uapi/linux/usbdevice_fs.h tools/include/uapi/linux/usbdevice_fs.h
>   $ git diff
>   diff --git a/tools/include/uapi/linux/usbdevice_fs.h b/tools/include/uapi/linux/usbdevice_fs.h
>   index 78efe870c2b7..cf525cddeb94 100644
>   --- a/tools/include/uapi/linux/usbdevice_fs.h
>   +++ b/tools/include/uapi/linux/usbdevice_fs.h
>   @@ -158,6 +158,7 @@ struct usbdevfs_hub_portinfo {
>    #define USBDEVFS_CAP_MMAP                      0x20
>    #define USBDEVFS_CAP_DROP_PRIVILEGES           0x40
>    #define USBDEVFS_CAP_CONNINFO_EX               0x80
>   +#define USBDEVFS_CAP_SUSPEND                   0x100
> 
>    /* USBDEVFS_DISCONNECT_CLAIM flags & struct */
> 
>   @@ -223,5 +224,8 @@ struct usbdevfs_streams {
>     * extending size of the data returned.
>     */
>    #define USBDEVFS_CONNINFO_EX(len)  _IOC(_IOC_READ, 'U', 32, len)
>   +#define USBDEVFS_FORBID_SUSPEND    _IO('U', 33)
>   +#define USBDEVFS_ALLOW_SUSPEND     _IO('U', 34)
>   +#define USBDEVFS_WAIT_FOR_RESUME   _IO('U', 35)
> 
>    #endif /* _UAPI_LINUX_USBDEVICE_FS_H */
>   $ tools/perf/trace/beauty/usbdevfs_ioctl.sh  > after
>   $ diff -u before after
>   --- before	2019-09-27 11:41:50.634867620 -0300
>   +++ after	2019-09-27 11:42:07.453102978 -0300
>   @@ -24,6 +24,9 @@
>    	[30] = "DROP_PRIVILEGES",
>    	[31] = "GET_SPEED",
>    	[32] = "CONNINFO_EX",
>   +	[33] = "FORBID_SUSPEND",
>   +	[34] = "ALLOW_SUSPEND",
>   +	[35] = "WAIT_FOR_RESUME",
>    	[3] = "RESETEP",
>    	[4] = "SETINTERFACE",
>    	[5] = "SETCONFIGURATION",
>   $
> 
> This addresses the following perf build warning:
> 
>   Warning: Kernel ABI header at 'tools/include/uapi/linux/usbdevice_fs.h' differs from latest version at 'include/uapi/linux/usbdevice_fs.h'
>   diff -u tools/include/uapi/linux/usbdevice_fs.h include/uapi/linux/usbdevice_fs.h

This may sound silly, and undoubtedly the question has been asked 
before.  Nevertheless...

Why go to the time and trouble to detect differences between 
tools/include/uapi/linux/usbdevice_fs.h and 
include/uapi/linux/usbdevice_fs.h?  Why not just make the first a 
symbolic link to the second?  Or get rid of the first entirely, and 
change the source code so that it #include's the second?

Alan Stern