a4e8b91254
Sysfs file poll implementation is scattered over sysfs and kobject. Event numbering is done in sysfs_dirent but wait itself is done on kobject. This not only unecessarily bloats both kobject and sysfs_dirent but is also buggy - if a sysfs_dirent is removed while there still are pollers, the associaton betwen the kobject and sysfs_dirent breaks and kobject may be freed with the pollers still sleeping on it. This patch moves whole poll implementation into sysfs_open_dirent. Each time a sysfs_open_dirent is created, event number restarts from 1 and pollers sleep on sysfs_open_dirent. As event sequence number is meaningless without any open file and pollers should have open file and thus sysfs_open_dirent, this ephemeral event counting works and is a saner implementation. This patch fixes the dnagling sleepers bug and reduces the sizes of kobject and sysfs_dirent by one pointer. Signed-off-by: Tejun Heo <htejun@gmail.com> Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
156 lines
4 KiB
C
156 lines
4 KiB
C
struct sysfs_open_dirent;
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/* type-specific structures for sysfs_dirent->s_* union members */
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struct sysfs_elem_dir {
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struct kobject *kobj;
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/* children list starts here and goes through sd->s_sibling */
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struct sysfs_dirent *children;
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};
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struct sysfs_elem_symlink {
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struct sysfs_dirent *target_sd;
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};
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struct sysfs_elem_attr {
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struct attribute *attr;
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struct sysfs_open_dirent *open;
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};
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struct sysfs_elem_bin_attr {
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struct bin_attribute *bin_attr;
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};
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/*
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* sysfs_dirent - the building block of sysfs hierarchy. Each and
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* every sysfs node is represented by single sysfs_dirent.
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*
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* As long as s_count reference is held, the sysfs_dirent itself is
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* accessible. Dereferencing s_elem or any other outer entity
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* requires s_active reference.
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*/
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struct sysfs_dirent {
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atomic_t s_count;
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atomic_t s_active;
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struct sysfs_dirent *s_parent;
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struct sysfs_dirent *s_sibling;
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const char *s_name;
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union {
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struct sysfs_elem_dir s_dir;
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struct sysfs_elem_symlink s_symlink;
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struct sysfs_elem_attr s_attr;
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struct sysfs_elem_bin_attr s_bin_attr;
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};
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unsigned int s_flags;
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ino_t s_ino;
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umode_t s_mode;
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struct iattr *s_iattr;
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};
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#define SD_DEACTIVATED_BIAS INT_MIN
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#define SYSFS_TYPE_MASK 0x00ff
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#define SYSFS_DIR 0x0001
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#define SYSFS_KOBJ_ATTR 0x0002
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#define SYSFS_KOBJ_BIN_ATTR 0x0004
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#define SYSFS_KOBJ_LINK 0x0008
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#define SYSFS_COPY_NAME (SYSFS_DIR | SYSFS_KOBJ_LINK)
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#define SYSFS_FLAG_MASK ~SYSFS_TYPE_MASK
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#define SYSFS_FLAG_REMOVED 0x0200
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static inline unsigned int sysfs_type(struct sysfs_dirent *sd)
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{
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return sd->s_flags & SYSFS_TYPE_MASK;
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}
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/*
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* Context structure to be used while adding/removing nodes.
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*/
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struct sysfs_addrm_cxt {
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struct sysfs_dirent *parent_sd;
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struct inode *parent_inode;
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struct sysfs_dirent *removed;
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int cnt;
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};
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/*
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* mount.c
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*/
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extern struct sysfs_dirent sysfs_root;
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extern struct super_block *sysfs_sb;
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extern struct kmem_cache *sysfs_dir_cachep;
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/*
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* dir.c
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*/
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extern struct mutex sysfs_mutex;
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extern struct mutex sysfs_rename_mutex;
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extern spinlock_t sysfs_assoc_lock;
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extern const struct file_operations sysfs_dir_operations;
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extern const struct inode_operations sysfs_dir_inode_operations;
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struct dentry *sysfs_get_dentry(struct sysfs_dirent *sd);
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struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent *sd);
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void sysfs_put_active(struct sysfs_dirent *sd);
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struct sysfs_dirent *sysfs_get_active_two(struct sysfs_dirent *sd);
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void sysfs_put_active_two(struct sysfs_dirent *sd);
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void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
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struct sysfs_dirent *parent_sd);
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int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
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void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
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void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
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struct sysfs_dirent *sysfs_find_dirent(struct sysfs_dirent *parent_sd,
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const unsigned char *name);
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struct sysfs_dirent *sysfs_get_dirent(struct sysfs_dirent *parent_sd,
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const unsigned char *name);
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struct sysfs_dirent *sysfs_new_dirent(const char *name, umode_t mode, int type);
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void release_sysfs_dirent(struct sysfs_dirent *sd);
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int sysfs_create_subdir(struct kobject *kobj, const char *name,
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struct sysfs_dirent **p_sd);
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void sysfs_remove_subdir(struct sysfs_dirent *sd);
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static inline struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
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{
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if (sd) {
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WARN_ON(!atomic_read(&sd->s_count));
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atomic_inc(&sd->s_count);
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}
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return sd;
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}
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static inline void sysfs_put(struct sysfs_dirent *sd)
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{
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if (sd && atomic_dec_and_test(&sd->s_count))
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release_sysfs_dirent(sd);
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}
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/*
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* inode.c
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*/
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struct inode *sysfs_get_inode(struct sysfs_dirent *sd);
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int sysfs_setattr(struct dentry *dentry, struct iattr *iattr);
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int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const char *name);
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/*
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* file.c
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*/
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extern const struct file_operations sysfs_file_operations;
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int sysfs_add_file(struct sysfs_dirent *dir_sd,
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const struct attribute *attr, int type);
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/*
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* bin.c
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*/
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extern const struct file_operations bin_fops;
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/*
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* symlink.c
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*/
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extern const struct inode_operations sysfs_symlink_inode_operations;
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