From e52eec13cd6b7f30ab19081b387813e03e592ae5 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 8 Sep 2010 16:54:17 +0200 Subject: SYSFS: Allow boot time switching between deprecated and modern sysfs layout I have some systems which need legacy sysfs due to old tools that are making assumptions that a directory can never be a symlink to another directory, and it's a big hazzle to compile separate kernels for them. This patch turns CONFIG_SYSFS_DEPRECATED into a run time option that can be switched on/off the kernel command line. This way the same binary can be used in both cases with just a option on the command line. The old CONFIG_SYSFS_DEPRECATED_V2 option is still there to set the default. I kept the weird name to not break existing config files. Also the compat code can be still completely disabled by undefining CONFIG_SYSFS_DEPRECATED_SWITCH -- just the optimizer takes care of this now instead of lots of ifdefs. This makes the code look nicer. v2: This is an updated version on top of Kay's patch to only handle the block devices. I tested it on my old systems and that seems to work. Cc: axboe@kernel.dk Signed-off-by: Andi Kleen Cc: Kay Sievers Signed-off-by: Greg Kroah-Hartman --- drivers/base/class.c | 4 ++-- drivers/base/core.c | 26 +++++++++++++++++--------- 2 files changed, 19 insertions(+), 11 deletions(-) (limited to 'drivers') diff --git a/drivers/base/class.c b/drivers/base/class.c index 1078969889f..9c63a5687d6 100644 --- a/drivers/base/class.c +++ b/drivers/base/class.c @@ -184,9 +184,9 @@ int __class_register(struct class *cls, struct lock_class_key *key) if (!cls->dev_kobj) cls->dev_kobj = sysfs_dev_char_kobj; -#if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK) +#if defined(CONFIG_BLOCK) /* let the block class directory show up in the root of sysfs */ - if (cls != &block_class) + if (!sysfs_deprecated || cls != &block_class) cp->class_subsys.kobj.kset = class_kset; #else cp->class_subsys.kobj.kset = class_kset; diff --git a/drivers/base/core.c b/drivers/base/core.c index 6cf9069f315..f7f906f0a2f 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -26,6 +26,19 @@ #include "base.h" #include "power/power.h" +#ifdef CONFIG_SYSFS_DEPRECATED +#ifdef CONFIG_SYSFS_DEPRECATED_V2 +long sysfs_deprecated = 1; +#else +long sysfs_deprecated = 0; +#endif +static __init int sysfs_deprecated_setup(char *arg) +{ + return strict_strtol(arg, 10, &sysfs_deprecated); +} +early_param("sysfs.deprecated", sysfs_deprecated_setup); +#endif + int (*platform_notify)(struct device *dev) = NULL; int (*platform_notify_remove)(struct device *dev) = NULL; static struct kobject *dev_kobj; @@ -617,14 +630,13 @@ static struct kobject *get_device_parent(struct device *dev, struct kobject *parent_kobj; struct kobject *k; -#ifdef CONFIG_SYSFS_DEPRECATED /* block disks show up in /sys/block */ - if (dev->class == &block_class) { + if (sysfs_deprecated && dev->class == &block_class) { if (parent && parent->class == &block_class) return &parent->kobj; return &block_class.p->class_subsys.kobj; } -#endif + /* * If we have no parent, we live in "virtual". * Class-devices with a non class-device as parent, live @@ -707,11 +719,9 @@ static int device_add_class_symlinks(struct device *dev) goto out_subsys; } -#ifdef CONFIG_SYSFS_DEPRECATED /* /sys/block has directories and does not need symlinks */ - if (dev->class == &block_class) + if (sysfs_deprecated && dev->class == &block_class) return 0; -#endif /* link in the class directory pointing to the device */ error = sysfs_create_link(&dev->class->p->class_subsys.kobj, @@ -738,10 +748,8 @@ static void device_remove_class_symlinks(struct device *dev) if (dev->parent && device_is_not_partition(dev)) sysfs_remove_link(&dev->kobj, "device"); sysfs_remove_link(&dev->kobj, "subsystem"); -#ifdef CONFIG_SYSFS_DEPRECATED - if (dev->class == &block_class) + if (sysfs_deprecated && dev->class == &block_class) return; -#endif sysfs_delete_link(&dev->class->p->class_subsys.kobj, &dev->kobj, dev_name(dev)); } -- cgit v1.2.3-70-g09d2