From 4d45f7974ccf0aa783034fef2661573b3a28609e Mon Sep 17 00:00:00 2001 From: Nicolai Stange Date: Tue, 22 Mar 2016 14:11:18 +0100 Subject: [PATCH] debugfs: unproxify files created through debugfs_create_bool() Currently, the struct file_operations fops_bool associated with files created through the debugfs_create_bool() helpers are not file lifetime aware. Thus, a lifetime managing proxy is created around fops_bool each time such a file is opened which is an unnecessary waste of resources. Implement file lifetime management for the fops_bool file_operations. Namely, make debugfs_read_file_bool() and debugfs_write_file_bool() safe against file removals by means of debugfs_use_file_start() and debugfs_use_file_finish(). Make debugfs_create_bool() create its files in non-proxying operation mode through debugfs_create_mode_unsafe(). Finally, purge debugfs_create_mode() as debugfs_create_bool() had been its last user. Signed-off-by: Nicolai Stange Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/file.c | 41 ++++++++++++++++++++--------------------- 1 file changed, 20 insertions(+), 21 deletions(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index 4b3967e86e97..8a548bee1b3d 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -312,22 +312,6 @@ ssize_t debugfs_attr_write(struct file *file, const char __user *buf, } EXPORT_SYMBOL_GPL(debugfs_attr_write); -static struct dentry *debugfs_create_mode(const char *name, umode_t mode, - struct dentry *parent, void *value, - const struct file_operations *fops, - const struct file_operations *fops_ro, - const struct file_operations *fops_wo) -{ - /* if there are no write bits set, make read only */ - if (!(mode & S_IWUGO)) - return debugfs_create_file(name, mode, parent, value, fops_ro); - /* if there are no read bits set, make write only */ - if (!(mode & S_IRUGO)) - return debugfs_create_file(name, mode, parent, value, fops_wo); - - return debugfs_create_file(name, mode, parent, value, fops); -} - static struct dentry *debugfs_create_mode_unsafe(const char *name, umode_t mode, struct dentry *parent, void *value, const struct file_operations *fops, @@ -756,9 +740,17 @@ ssize_t debugfs_read_file_bool(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { char buf[3]; - bool *val = file->private_data; + bool val; + int r, srcu_idx; - if (*val) + r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx); + if (likely(!r)) + val = *(bool *)file->private_data; + debugfs_use_file_finish(srcu_idx); + if (r) + return r; + + if (val) buf[0] = 'Y'; else buf[0] = 'N'; @@ -774,6 +766,7 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf, char buf[32]; size_t buf_size; bool bv; + int r, srcu_idx; bool *val = file->private_data; buf_size = min(count, (sizeof(buf)-1)); @@ -781,8 +774,14 @@ ssize_t debugfs_write_file_bool(struct file *file, const char __user *user_buf, return -EFAULT; buf[buf_size] = '\0'; - if (strtobool(buf, &bv) == 0) - *val = bv; + if (strtobool(buf, &bv) == 0) { + r = debugfs_use_file_start(F_DENTRY(file), &srcu_idx); + if (likely(!r)) + *val = bv; + debugfs_use_file_finish(srcu_idx); + if (r) + return r; + } return count; } @@ -834,7 +833,7 @@ static const struct file_operations fops_bool_wo = { struct dentry *debugfs_create_bool(const char *name, umode_t mode, struct dentry *parent, bool *value) { - return debugfs_create_mode(name, mode, parent, value, &fops_bool, + return debugfs_create_mode_unsafe(name, mode, parent, value, &fops_bool, &fops_bool_ro, &fops_bool_wo); } EXPORT_SYMBOL_GPL(debugfs_create_bool);