diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 67299e8b734e..47dc96dfe386 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -100,8 +100,16 @@ int debugfs_file_get(struct dentry *dentry) if (!fsd) return -ENOMEM; - fsd->real_fops = (void *)((unsigned long)d_fsd & - ~DEBUGFS_FSDATA_IS_REAL_FOPS_BIT); + if ((unsigned long)d_fsd & DEBUGFS_FSDATA_IS_SHORT_FOPS_BIT) { + fsd->real_fops = NULL; + fsd->short_fops = (void *)((unsigned long)d_fsd & + ~(DEBUGFS_FSDATA_IS_REAL_FOPS_BIT | + DEBUGFS_FSDATA_IS_SHORT_FOPS_BIT)); + } else { + fsd->real_fops = (void *)((unsigned long)d_fsd & + ~DEBUGFS_FSDATA_IS_REAL_FOPS_BIT); + fsd->short_fops = NULL; + } refcount_set(&fsd->active_users, 1); init_completion(&fsd->active_users_drained); INIT_LIST_HEAD(&fsd->cancellations); @@ -241,9 +249,10 @@ static int debugfs_locked_down(struct inode *inode, { if ((inode->i_mode & 07777 & ~0444) == 0 && !(filp->f_mode & FMODE_WRITE) && - !real_fops->unlocked_ioctl && - !real_fops->compat_ioctl && - !real_fops->mmap) + (!real_fops || + (!real_fops->unlocked_ioctl && + !real_fops->compat_ioctl && + !real_fops->mmap))) return 0; if (security_locked_down(LOCKDOWN_DEBUGFS)) @@ -316,19 +325,38 @@ static ret_type full_proxy_ ## name(proto) \ return r; \ } -FULL_PROXY_FUNC(llseek, loff_t, filp, - PROTO(struct file *filp, loff_t offset, int whence), - ARGS(filp, offset, whence)); +#define FULL_PROXY_FUNC_BOTH(name, ret_type, filp, proto, args) \ +static ret_type full_proxy_ ## name(proto) \ +{ \ + struct dentry *dentry = F_DENTRY(filp); \ + struct debugfs_fsdata *fsd; \ + ret_type r; \ + \ + r = debugfs_file_get(dentry); \ + if (unlikely(r)) \ + return r; \ + fsd = dentry->d_fsdata; \ + if (fsd->real_fops) \ + r = fsd->real_fops->name(args); \ + else \ + r = fsd->short_fops->name(args); \ + debugfs_file_put(dentry); \ + return r; \ +} -FULL_PROXY_FUNC(read, ssize_t, filp, - PROTO(struct file *filp, char __user *buf, size_t size, - loff_t *ppos), - ARGS(filp, buf, size, ppos)); +FULL_PROXY_FUNC_BOTH(llseek, loff_t, filp, + PROTO(struct file *filp, loff_t offset, int whence), + ARGS(filp, offset, whence)); -FULL_PROXY_FUNC(write, ssize_t, filp, - PROTO(struct file *filp, const char __user *buf, size_t size, - loff_t *ppos), - ARGS(filp, buf, size, ppos)); +FULL_PROXY_FUNC_BOTH(read, ssize_t, filp, + PROTO(struct file *filp, char __user *buf, size_t size, + loff_t *ppos), + ARGS(filp, buf, size, ppos)); + +FULL_PROXY_FUNC_BOTH(write, ssize_t, filp, + PROTO(struct file *filp, const char __user *buf, + size_t size, loff_t *ppos), + ARGS(filp, buf, size, ppos)); FULL_PROXY_FUNC(unlocked_ioctl, long, filp, PROTO(struct file *filp, unsigned int cmd, unsigned long arg), @@ -363,7 +391,7 @@ static int full_proxy_release(struct inode *inode, struct file *filp) * not to leak any resources. Releasers must not assume that * ->i_private is still being meaningful here. */ - if (real_fops->release) + if (real_fops && real_fops->release) r = real_fops->release(inode, filp); replace_fops(filp, d_inode(dentry)->i_fop); @@ -373,39 +401,48 @@ static int full_proxy_release(struct inode *inode, struct file *filp) } static void __full_proxy_fops_init(struct file_operations *proxy_fops, - const struct file_operations *real_fops) + struct debugfs_fsdata *fsd) { proxy_fops->release = full_proxy_release; - if (real_fops->llseek) + + if ((fsd->real_fops && fsd->real_fops->llseek) || + (fsd->short_fops && fsd->short_fops->llseek)) proxy_fops->llseek = full_proxy_llseek; - if (real_fops->read) + + if ((fsd->real_fops && fsd->real_fops->read) || + (fsd->short_fops && fsd->short_fops->read)) proxy_fops->read = full_proxy_read; - if (real_fops->write) + + if ((fsd->real_fops && fsd->real_fops->write) || + (fsd->short_fops && fsd->short_fops->write)) proxy_fops->write = full_proxy_write; - if (real_fops->poll) + + if (fsd->real_fops && fsd->real_fops->poll) proxy_fops->poll = full_proxy_poll; - if (real_fops->unlocked_ioctl) + + if (fsd->real_fops && fsd->real_fops->unlocked_ioctl) proxy_fops->unlocked_ioctl = full_proxy_unlocked_ioctl; } static int full_proxy_open(struct inode *inode, struct file *filp) { struct dentry *dentry = F_DENTRY(filp); - const struct file_operations *real_fops = NULL; + const struct file_operations *real_fops; struct file_operations *proxy_fops = NULL; + struct debugfs_fsdata *fsd; int r; r = debugfs_file_get(dentry); if (r) return r == -EIO ? -ENOENT : r; - real_fops = debugfs_real_fops(filp); - + fsd = dentry->d_fsdata; + real_fops = fsd->real_fops; r = debugfs_locked_down(inode, filp, real_fops); if (r) goto out; - if (!fops_get(real_fops)) { + if (real_fops && !fops_get(real_fops)) { #ifdef CONFIG_MODULES if (real_fops->owner && real_fops->owner->state == MODULE_STATE_GOING) { @@ -426,11 +463,14 @@ static int full_proxy_open(struct inode *inode, struct file *filp) r = -ENOMEM; goto free_proxy; } - __full_proxy_fops_init(proxy_fops, real_fops); + __full_proxy_fops_init(proxy_fops, fsd); replace_fops(filp, proxy_fops); - if (real_fops->open) { - r = real_fops->open(inode, filp); + if (!real_fops || real_fops->open) { + if (real_fops) + r = real_fops->open(inode, filp); + else + r = simple_open(inode, filp); if (r) { replace_fops(filp, d_inode(dentry)->i_fop); goto free_proxy; diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 66d9b3b4c588..38a9c7eb97e6 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -412,7 +412,7 @@ static struct dentry *end_creating(struct dentry *dentry) static struct dentry *__debugfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *proxy_fops, - const struct file_operations *real_fops) + const void *real_fops) { struct dentry *dentry; struct inode *inode; @@ -450,49 +450,38 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, return end_creating(dentry); } -/** - * debugfs_create_file - create a file in the debugfs filesystem - * @name: a pointer to a string containing the name of the file to create. - * @mode: the permission that the file should have. - * @parent: a pointer to the parent dentry for this file. This should be a - * directory dentry if set. If this parameter is NULL, then the - * file will be created in the root of the debugfs filesystem. - * @data: a pointer to something that the caller will want to get to later - * on. The inode.i_private pointer will point to this value on - * the open() call. - * @fops: a pointer to a struct file_operations that should be used for - * this file. - * - * This is the basic "create a file" function for debugfs. It allows for a - * wide range of flexibility in creating a file, or a directory (if you want - * to create a directory, the debugfs_create_dir() function is - * recommended to be used instead.) - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the debugfs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be - * returned. - * - * If debugfs is not enabled in the kernel, the value -%ENODEV will be - * returned. - * - * NOTE: it's expected that most callers should _ignore_ the errors returned - * by this function. Other debugfs functions handle the fact that the "dentry" - * passed to them could be an error and they don't crash in that case. - * Drivers should generally work fine even if debugfs fails to init anyway. - */ -struct dentry *debugfs_create_file(const char *name, umode_t mode, - struct dentry *parent, void *data, - const struct file_operations *fops) +struct dentry *debugfs_create_file_full(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops) { + if (WARN_ON((unsigned long)fops & + (DEBUGFS_FSDATA_IS_SHORT_FOPS_BIT | + DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))) + return ERR_PTR(-EINVAL); return __debugfs_create_file(name, mode, parent, data, fops ? &debugfs_full_proxy_file_operations : &debugfs_noop_file_operations, fops); } -EXPORT_SYMBOL_GPL(debugfs_create_file); +EXPORT_SYMBOL_GPL(debugfs_create_file_full); + +struct dentry *debugfs_create_file_short(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct debugfs_short_fops *fops) +{ + if (WARN_ON((unsigned long)fops & + (DEBUGFS_FSDATA_IS_SHORT_FOPS_BIT | + DEBUGFS_FSDATA_IS_REAL_FOPS_BIT))) + return ERR_PTR(-EINVAL); + + return __debugfs_create_file(name, mode, parent, data, + fops ? &debugfs_full_proxy_file_operations : + &debugfs_noop_file_operations, + (const void *)((unsigned long)fops | + DEBUGFS_FSDATA_IS_SHORT_FOPS_BIT)); +} +EXPORT_SYMBOL_GPL(debugfs_create_file_short); /** * debugfs_create_file_unsafe - create a file in the debugfs filesystem diff --git a/fs/debugfs/internal.h b/fs/debugfs/internal.h index dae80c2a469e..a3edfa4f0d8e 100644 --- a/fs/debugfs/internal.h +++ b/fs/debugfs/internal.h @@ -18,6 +18,7 @@ extern const struct file_operations debugfs_full_proxy_file_operations; struct debugfs_fsdata { const struct file_operations *real_fops; + const struct debugfs_short_fops *short_fops; union { /* automount_fn is used when real_fops is NULL */ debugfs_automount_t automount; @@ -39,6 +40,11 @@ struct debugfs_fsdata { * pointer gets its lowest bit set. */ #define DEBUGFS_FSDATA_IS_REAL_FOPS_BIT BIT(0) +/* + * A dentry's ->d_fsdata, when pointing to real fops, is with + * short fops instead of full fops. + */ +#define DEBUGFS_FSDATA_IS_SHORT_FOPS_BIT BIT(1) /* Access BITS */ #define DEBUGFS_ALLOW_API BIT(0) diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h index 0928a6c8ae1e..59444b495d49 100644 --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -71,9 +71,63 @@ typedef struct vfsmount *(*debugfs_automount_t)(struct dentry *, void *); struct dentry *debugfs_lookup(const char *name, struct dentry *parent); -struct dentry *debugfs_create_file(const char *name, umode_t mode, - struct dentry *parent, void *data, - const struct file_operations *fops); +struct debugfs_short_fops { + ssize_t (*read)(struct file *, char __user *, size_t, loff_t *); + ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *); + loff_t (*llseek) (struct file *, loff_t, int); +}; + +struct dentry *debugfs_create_file_full(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops); +struct dentry *debugfs_create_file_short(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct debugfs_short_fops *fops); + +/** + * debugfs_create_file - create a file in the debugfs filesystem + * @name: a pointer to a string containing the name of the file to create. + * @mode: the permission that the file should have. + * @parent: a pointer to the parent dentry for this file. This should be a + * directory dentry if set. If this parameter is NULL, then the + * file will be created in the root of the debugfs filesystem. + * @data: a pointer to something that the caller will want to get to later + * on. The inode.i_private pointer will point to this value on + * the open() call. + * @fops: a pointer to a struct file_operations or struct debugfs_short_fops that + * should be used for this file. + * + * This is the basic "create a file" function for debugfs. It allows for a + * wide range of flexibility in creating a file, or a directory (if you want + * to create a directory, the debugfs_create_dir() function is + * recommended to be used instead.) + * + * This function will return a pointer to a dentry if it succeeds. This + * pointer must be passed to the debugfs_remove() function when the file is + * to be removed (no automatic cleanup happens if your module is unloaded, + * you are responsible here.) If an error occurs, ERR_PTR(-ERROR) will be + * returned. + * + * If debugfs is not enabled in the kernel, the value -%ENODEV will be + * returned. + * + * If fops points to a struct debugfs_short_fops, then simple_open() will be + * used for the open, and only read/write/llseek are supported and are proxied, + * so no module reference or release are needed. + * + * NOTE: it's expected that most callers should _ignore_ the errors returned + * by this function. Other debugfs functions handle the fact that the "dentry" + * passed to them could be an error and they don't crash in that case. + * Drivers should generally work fine even if debugfs fails to init anyway. + */ +#define debugfs_create_file(name, mode, parent, data, fops) \ + _Generic(fops, \ + const struct file_operations *: debugfs_create_file_full, \ + const struct debugfs_short_fops *: debugfs_create_file_short, \ + struct file_operations *: debugfs_create_file_full, \ + struct debugfs_short_fops *: debugfs_create_file_short) \ + (name, mode, parent, data, fops) + struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops); @@ -207,7 +261,7 @@ static inline struct dentry *debugfs_lookup(const char *name, static inline struct dentry *debugfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, - const struct file_operations *fops) + const void *fops) { return ERR_PTR(-ENODEV); }