diff options
Diffstat (limited to 'Documentation/filesystems/sysfs.txt')
-rw-r--r-- | Documentation/filesystems/sysfs.txt | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt index a1426cabcef1..5b5311f9358d 100644 --- a/Documentation/filesystems/sysfs.txt +++ b/Documentation/filesystems/sysfs.txt @@ -116,6 +116,27 @@ static struct device_attribute dev_attr_foo = { .store = store_foo, }; +Note as stated in include/linux/kernel.h "OTHER_WRITABLE? Generally +considered a bad idea." so trying to set a sysfs file writable for +everyone will fail reverting to RO mode for "Others". + +For the common cases sysfs.h provides convenience macros to make +defining attributes easier as well as making code more concise and +readable. The above case could be shortened to: + +static struct device_attribute dev_attr_foo = __ATTR_RW(foo); + +the list of helpers available to define your wrapper function is: +__ATTR_RO(name): assumes default name_show and mode 0444 +__ATTR_WO(name): assumes a name_store only and is restricted to mode + 0200 that is root write access only. +__ATTR_RO_MODE(name, mode): fore more restrictive RO access currently + only use case is the EFI System Resource Table + (see drivers/firmware/efi/esrt.c) +__ATTR_RW(name): assumes default name_show, name_store and setting + mode to 0644. +__ATTR_NULL: which sets the name to NULL and is used as end of list + indicator (see: kernel/workqueue.c) Subsystem-Specific Callbacks ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -344,7 +365,9 @@ struct bus_attribute { Declaring: -BUS_ATTR(_name, _mode, _show, _store) +static BUS_ATTR_RW(name); +static BUS_ATTR_RO(name); +static BUS_ATTR_WO(name); Creation/Removal: |