diff options
| -rw-r--r-- | fs/debugfs/file.c | 48 | ||||
| -rw-r--r-- | fs/debugfs/inode.c | 29 | ||||
| -rw-r--r-- | fs/debugfs/internal.h | 2 | ||||
| -rw-r--r-- | include/linux/debugfs.h | 11 |
4 files changed, 84 insertions, 6 deletions
diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index b6f5ddab66bf..6644bfdea2f8 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -109,6 +109,54 @@ const struct file_operations *debugfs_real_fops(const struct file *filp) } EXPORT_SYMBOL_GPL(debugfs_real_fops); +/** + * debugfs_file_get - mark the beginning of file data access + * @dentry: the dentry object whose data is being accessed. + * + * Up to a matching call to debugfs_file_put(), any successive call + * into the file removing functions debugfs_remove() and + * debugfs_remove_recursive() will block. Since associated private + * file data may only get freed after a successful return of any of + * the removal functions, you may safely access it after a successful + * call to debugfs_file_get() without worrying about lifetime issues. + * + * If -%EIO is returned, the file has already been removed and thus, + * it is not safe to access any of its data. If, on the other hand, + * it is allowed to access the file data, zero is returned. + */ +int debugfs_file_get(struct dentry *dentry) +{ + struct debugfs_fsdata *fsd = dentry->d_fsdata; + + /* Avoid starvation of removers. */ + if (d_unlinked(dentry)) + return -EIO; + + if (!refcount_inc_not_zero(&fsd->active_users)) + return -EIO; + + return 0; +} +EXPORT_SYMBOL_GPL(debugfs_file_get); + +/** + * debugfs_file_put - mark the end of file data access + * @dentry: the dentry object formerly passed to + * debugfs_file_get(). + * + * Allow any ongoing concurrent call into debugfs_remove() or + * debugfs_remove_recursive() blocked by a former call to + * debugfs_file_get() to proceed and return to its caller. + */ +void debugfs_file_put(struct dentry *dentry) +{ + struct debugfs_fsdata *fsd = dentry->d_fsdata; + + if (refcount_dec_and_test(&fsd->active_users)) + complete(&fsd->active_users_drained); +} +EXPORT_SYMBOL_GPL(debugfs_file_put); + static int open_proxy_open(struct inode *inode, struct file *filp) { const struct dentry *dentry = F_DENTRY(filp); diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index a9c3d3e9af39..6449eb935540 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -374,6 +374,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, inode->i_fop = proxy_fops; fsd->real_fops = real_fops; + refcount_set(&fsd->active_users, 1); dentry->d_fsdata = fsd; d_instantiate(dentry, inode); @@ -631,18 +632,34 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, } EXPORT_SYMBOL_GPL(debugfs_create_symlink); +static void __debugfs_remove_file(struct dentry *dentry, struct dentry *parent) +{ + struct debugfs_fsdata *fsd; + + simple_unlink(d_inode(parent), dentry); + d_delete(dentry); + fsd = dentry->d_fsdata; + init_completion(&fsd->active_users_drained); + if (!refcount_dec_and_test(&fsd->active_users)) + wait_for_completion(&fsd->active_users_drained); +} + static int __debugfs_remove(struct dentry *dentry, struct dentry *parent) { int ret = 0; if (simple_positive(dentry)) { dget(dentry); - if (d_is_dir(dentry)) - ret = simple_rmdir(d_inode(parent), dentry); - else - simple_unlink(d_inode(parent), dentry); - if (!ret) - d_delete(dentry); + if (!d_is_reg(dentry)) { + if (d_is_dir(dentry)) + ret = simple_rmdir(d_inode(parent), dentry); + else + simple_unlink(d_inode(parent), dentry); + if (!ret) + d_delete(dentry); + } else { + __debugfs_remove_file(dentry, parent); + } dput(dentry); } return ret; diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h index 512601eed3ce..0eea99432840 100644 --- a/fs/debugfs/internal.h +++ b/fs/debugfs/internal.h @@ -21,6 +21,8 @@ extern const struct file_operations debugfs_full_proxy_file_operations; struct debugfs_fsdata { const struct file_operations *real_fops; + refcount_t active_users; + struct completion active_users_drained; }; #endif /* _DEBUGFS_INTERNAL_H_ */ diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h index cbee5f4a02a3..3b914d588148 100644 --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -98,6 +98,9 @@ void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu); const struct file_operations *debugfs_real_fops(const struct file *filp) __must_hold(&debugfs_srcu); +int debugfs_file_get(struct dentry *dentry); +void debugfs_file_put(struct dentry *dentry); + ssize_t debugfs_attr_read(struct file *file, char __user *buf, size_t len, loff_t *ppos); ssize_t debugfs_attr_write(struct file *file, const char __user *buf, @@ -236,6 +239,14 @@ static inline void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu) { } +static inline int debugfs_file_get(struct dentry *dentry) +{ + return 0; +} + +static inline void debugfs_file_put(struct dentry *dentry) +{ } + static inline ssize_t debugfs_attr_read(struct file *file, char __user *buf, size_t len, loff_t *ppos) { |