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authorDan Williams <dan.j.williams@intel.com>2008-04-21 21:51:07 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2008-07-22 08:54:40 +0400
commite105b8bfc769b0545b6f0f395179d1e43cbee822 (patch)
tree23a1f0839547829c4ca6e89cd40adf285eb9feb6 /drivers/base/class.c
parent93ded9b8fd42abe2c3607097963d8de6ad9117eb (diff)
downloadlinux-e105b8bfc769b0545b6f0f395179d1e43cbee822.tar.xz
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.c4
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)