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| author | Dan Williams <dan.j.williams@intel.com> | 2008-04-21 10:51:07 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2008-07-21 21:54:40 -0700 |
| commit | e105b8bfc769b0545b6f0f395179d1e43cbee822 (patch) | |
| tree | 23a1f0839547829c4ca6e89cd40adf285eb9feb6 /drivers/usb/core | |
| parent | 93ded9b8fd42abe2c3607097963d8de6ad9117eb (diff) | |
| download | op-kernel-dev-e105b8bfc769b0545b6f0f395179d1e43cbee822.zip op-kernel-dev-e105b8bfc769b0545b6f0f395179d1e43cbee822.tar.gz | |
sysfs: add /sys/dev/{char,block} to lookup sysfs path by major:minor
Why?:
There are occasions where userspace would like to access sysfs
attributes for a device but it may not know how sysfs has named the
device or the path. For example what is the sysfs path for
/dev/disk/by-id/ata-ST3160827AS_5MT004CK? With this change a call to
stat(2) returns the major:minor then userspace can see that
/sys/dev/block/8:32 links to /sys/block/sdc.
What are the alternatives?:
1/ Add an ioctl to return the path: Doable, but sysfs is meant to reduce
the need to proliferate ioctl interfaces into the kernel, so this
seems counter productive.
2/ Use udev to create these symlinks: Also doable, but it adds a
udev dependency to utilities that might be running in a limited
environment like an initramfs.
3/ Do a full-tree search of sysfs.
[kay.sievers@vrfy.org: fix duplicate registrations]
[kay.sievers@vrfy.org: cleanup suggestions]
Cc: Neil Brown <neilb@suse.de>
Cc: Tejun Heo <htejun@gmail.com>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Reviewed-by: SL Baur <steve@xemacs.org>
Acked-by: Kay Sievers <kay.sievers@vrfy.org>
Acked-by: Mark Lord <lkml@rtr.ca>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/core')
| -rw-r--r-- | drivers/usb/core/devio.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 54a350c..6fbc8f5 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -1792,6 +1792,11 @@ int __init usb_devio_init(void) usb_classdev_class = NULL; goto out; } + /* devices of this class shadow the major:minor of their parent + * device, so clear ->dev_kobj to prevent adding duplicate entries + * to /sys/dev + */ + usb_classdev_class->dev_kobj = NULL; usb_register_notify(&usbdev_nb); #endif |
