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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/base/class.c | |
| parent | Merge git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb-2.6 (diff) | |
| download | linux-dev-e105b8bfc769b0545b6f0f395179d1e43cbee822.tar.xz linux-dev-e105b8bfc769b0545b6f0f395179d1e43cbee822.zip | |
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/base/class.c')
| -rw-r--r-- | drivers/base/class.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/drivers/base/class.c b/drivers/base/class.c index e085af0ff94f..71ce3ff6bdf5 100644 --- a/drivers/base/class.c +++ b/drivers/base/class.c @@ -148,6 +148,10 @@ int class_register(struct class *cls) if (error) return error; + /* set the default /sys/dev directory for devices of this class */ + if (!cls->dev_kobj) + cls->dev_kobj = sysfs_dev_char_kobj; + #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK) /* let the block class directory show up in the root of sysfs */ if (cls != &block_class) |