From e105b8bfc769b0545b6f0f395179d1e43cbee822 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 21 Apr 2008 10:51:07 -0700 Subject: 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 Cc: Tejun Heo Acked-by: Kay Sievers Reviewed-by: SL Baur Acked-by: Kay Sievers Acked-by: Mark Lord Acked-by: H. Peter Anvin Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- drivers/base/class.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'drivers/base/class.c') 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) -- cgit v1.2.3