From c9afbec27089cd6b4e621b639f41c7fc726c3bf1 Mon Sep 17 00:00:00 2001 From: Nicolai Stange Date: Tue, 31 Oct 2017 00:15:52 +0100 Subject: [PATCH] debugfs: purge obsolete SRCU based removal protection Purge the SRCU based file removal race protection in favour of the new, refcount based debugfs_file_get()/debugfs_file_put() API. Fixes: 49d200deaa68 ("debugfs: prevent access to removed files' private data") Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/file.c | 48 ----------------------------------------- fs/debugfs/inode.c | 7 ------ include/linux/debugfs.h | 19 ---------------- lib/Kconfig.debug | 1 - 4 files changed, 75 deletions(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index d3a972b45ff0..53f5c9a2af88 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -22,7 +22,6 @@ #include #include #include -#include #include #include "internal.h" @@ -48,53 +47,6 @@ const struct file_operations debugfs_noop_file_operations = { .llseek = noop_llseek, }; -/** - * debugfs_use_file_start - mark the beginning of file data access - * @dentry: the dentry object whose data is being accessed. - * @srcu_idx: a pointer to some memory to store a SRCU index in. - * - * Up to a matching call to debugfs_use_file_finish(), 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_use_file_start() 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. - * - * Regardless of the return code, any call to - * debugfs_use_file_start() must be followed by a matching call - * to debugfs_use_file_finish(). - */ -int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx) - __acquires(&debugfs_srcu) -{ - *srcu_idx = srcu_read_lock(&debugfs_srcu); - barrier(); - if (d_unlinked(dentry)) - return -EIO; - return 0; -} -EXPORT_SYMBOL_GPL(debugfs_use_file_start); - -/** - * debugfs_use_file_finish - mark the end of file data access - * @srcu_idx: the SRCU index "created" by a former call to - * debugfs_use_file_start(). - * - * Allow any ongoing concurrent call into debugfs_remove() or - * debugfs_remove_recursive() blocked by a former call to - * debugfs_use_file_start() to proceed and return to its caller. - */ -void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu) -{ - srcu_read_unlock(&debugfs_srcu, srcu_idx); -} -EXPORT_SYMBOL_GPL(debugfs_use_file_finish); - #define F_DENTRY(filp) ((filp)->f_path.dentry) const struct file_operations *debugfs_real_fops(const struct file *filp) diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 6449eb935540..f587aded46b5 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -27,14 +27,11 @@ #include #include #include -#include #include "internal.h" #define DEBUGFS_DEFAULT_MODE 0700 -DEFINE_SRCU(debugfs_srcu); - static struct vfsmount *debugfs_mount; static int debugfs_mount_count; static bool debugfs_registered; @@ -693,8 +690,6 @@ void debugfs_remove(struct dentry *dentry) inode_unlock(d_inode(parent)); if (!ret) simple_release_fs(&debugfs_mount, &debugfs_mount_count); - - synchronize_srcu(&debugfs_srcu); } EXPORT_SYMBOL_GPL(debugfs_remove); @@ -768,8 +763,6 @@ void debugfs_remove_recursive(struct dentry *dentry) if (!__debugfs_remove(child, parent)) simple_release_fs(&debugfs_mount, &debugfs_mount_count); inode_unlock(d_inode(parent)); - - synchronize_srcu(&debugfs_srcu); } EXPORT_SYMBOL_GPL(debugfs_remove_recursive); diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h index c5eda259b9d6..9f821a43bb0d 100644 --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -23,7 +23,6 @@ struct device; struct file_operations; -struct srcu_struct; struct debugfs_blob_wrapper { void *data; @@ -43,8 +42,6 @@ struct debugfs_regset32 { extern struct dentry *arch_debugfs_dir; -extern struct srcu_struct debugfs_srcu; - #define DEFINE_DEBUGFS_ATTRIBUTE(__fops, __get, __set, __fmt) \ static int __fops ## _open(struct inode *inode, struct file *file) \ { \ @@ -90,11 +87,6 @@ struct dentry *debugfs_create_automount(const char *name, void debugfs_remove(struct dentry *dentry); void debugfs_remove_recursive(struct dentry *dentry); -int debugfs_use_file_start(const struct dentry *dentry, int *srcu_idx) - __acquires(&debugfs_srcu); - -void debugfs_use_file_finish(int srcu_idx) __releases(&debugfs_srcu); - const struct file_operations *debugfs_real_fops(const struct file *filp); int debugfs_file_get(struct dentry *dentry); @@ -227,17 +219,6 @@ static inline void debugfs_remove(struct dentry *dentry) static inline void debugfs_remove_recursive(struct dentry *dentry) { } -static inline int debugfs_use_file_start(const struct dentry *dentry, - int *srcu_idx) - __acquires(&debugfs_srcu) -{ - return 0; -} - -static inline void debugfs_use_file_finish(int srcu_idx) - __releases(&debugfs_srcu) -{ } - static inline int debugfs_file_get(struct dentry *dentry) { return 0; diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index dfdad67d8f6c..57fb43f521c3 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -280,7 +280,6 @@ config PAGE_OWNER config DEBUG_FS bool "Debug Filesystem" - select SRCU help debugfs is a virtual file system that kernel developers use to put debugging files into. Enable this option to be able to read and