4508a7a734
It works like this:
Open the file
Read all the contents.
Call poll requesting POLLERR or POLLPRI (so select/exceptfds works)
When poll returns,
close the file and go to top of loop.
or lseek to start of file and go back to the 'read'.
Events are signaled by an object manager calling
sysfs_notify(kobj, dir, attr);
If the dir is non-NULL, it is used to find a subdirectory which
contains the attribute (presumably created by sysfs_create_group).
This has a cost of one int per attribute, one wait_queuehead per kobject,
one int per open file.
The name "sysfs_notify" may be confused with the inotify
functionality. Maybe it would be nice to support inotify for sysfs
attributes as well?
This patch also uses sysfs_notify to allow /sys/block/md*/md/sync_action
to be pollable
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
196 lines
4.3 KiB
C
196 lines
4.3 KiB
C
/*
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* sysfs.h - definitions for the device driver filesystem
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*
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* Copyright (c) 2001,2002 Patrick Mochel
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* Copyright (c) 2004 Silicon Graphics, Inc.
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#ifndef _SYSFS_H_
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#define _SYSFS_H_
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#include <asm/atomic.h>
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struct kobject;
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struct module;
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struct attribute {
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const char * name;
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struct module * owner;
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mode_t mode;
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};
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struct attribute_group {
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const char * name;
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struct attribute ** attrs;
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};
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/**
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* Use these macros to make defining attributes easier. See include/linux/device.h
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* for examples..
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*/
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#define __ATTR(_name,_mode,_show,_store) { \
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.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE }, \
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.show = _show, \
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.store = _store, \
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}
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#define __ATTR_RO(_name) { \
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.attr = { .name = __stringify(_name), .mode = 0444, .owner = THIS_MODULE }, \
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.show = _name##_show, \
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}
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#define __ATTR_NULL { .attr = { .name = NULL } }
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#define attr_name(_attr) (_attr).attr.name
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struct vm_area_struct;
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struct bin_attribute {
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struct attribute attr;
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size_t size;
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void *private;
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ssize_t (*read)(struct kobject *, char *, loff_t, size_t);
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ssize_t (*write)(struct kobject *, char *, loff_t, size_t);
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int (*mmap)(struct kobject *, struct bin_attribute *attr,
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struct vm_area_struct *vma);
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};
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struct sysfs_ops {
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ssize_t (*show)(struct kobject *, struct attribute *,char *);
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ssize_t (*store)(struct kobject *,struct attribute *,const char *, size_t);
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};
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struct sysfs_dirent {
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atomic_t s_count;
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struct list_head s_sibling;
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struct list_head s_children;
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void * s_element;
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int s_type;
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umode_t s_mode;
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struct dentry * s_dentry;
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struct iattr * s_iattr;
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atomic_t s_event;
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};
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#define SYSFS_ROOT 0x0001
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#define SYSFS_DIR 0x0002
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#define SYSFS_KOBJ_ATTR 0x0004
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#define SYSFS_KOBJ_BIN_ATTR 0x0008
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#define SYSFS_KOBJ_LINK 0x0020
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#define SYSFS_NOT_PINNED (SYSFS_KOBJ_ATTR | SYSFS_KOBJ_BIN_ATTR | SYSFS_KOBJ_LINK)
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#ifdef CONFIG_SYSFS
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extern int
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sysfs_create_dir(struct kobject *);
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extern void
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sysfs_remove_dir(struct kobject *);
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extern int
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sysfs_rename_dir(struct kobject *, const char *new_name);
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extern int
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sysfs_create_file(struct kobject *, const struct attribute *);
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extern int
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sysfs_update_file(struct kobject *, const struct attribute *);
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extern int
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sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode);
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extern void
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sysfs_remove_file(struct kobject *, const struct attribute *);
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extern int
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sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name);
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extern void
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sysfs_remove_link(struct kobject *, const char * name);
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int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr);
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int sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr);
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int sysfs_create_group(struct kobject *, const struct attribute_group *);
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void sysfs_remove_group(struct kobject *, const struct attribute_group *);
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void sysfs_notify(struct kobject * k, char *dir, char *attr);
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#else /* CONFIG_SYSFS */
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static inline int sysfs_create_dir(struct kobject * k)
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{
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return 0;
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}
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static inline void sysfs_remove_dir(struct kobject * k)
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{
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;
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}
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static inline int sysfs_rename_dir(struct kobject * k, const char *new_name)
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{
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return 0;
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}
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static inline int sysfs_create_file(struct kobject * k, const struct attribute * a)
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{
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return 0;
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}
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static inline int sysfs_update_file(struct kobject * k, const struct attribute * a)
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{
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return 0;
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}
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static inline int sysfs_chmod_file(struct kobject *kobj, struct attribute *attr, mode_t mode)
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{
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return 0;
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}
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static inline void sysfs_remove_file(struct kobject * k, const struct attribute * a)
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{
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;
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}
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static inline int sysfs_create_link(struct kobject * k, struct kobject * t, const char * n)
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{
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return 0;
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}
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static inline void sysfs_remove_link(struct kobject * k, const char * name)
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{
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;
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}
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static inline int sysfs_create_bin_file(struct kobject * k, struct bin_attribute * a)
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{
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return 0;
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}
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static inline int sysfs_remove_bin_file(struct kobject * k, struct bin_attribute * a)
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{
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return 0;
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}
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static inline int sysfs_create_group(struct kobject * k, const struct attribute_group *g)
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{
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return 0;
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}
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static inline void sysfs_remove_group(struct kobject * k, const struct attribute_group * g)
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{
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;
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}
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static inline void sysfs_notify(struct kobject * k, char *dir, char *attr)
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{
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}
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#endif /* CONFIG_SYSFS */
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#endif /* _SYSFS_H_ */
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