When creating a config_group (resp. registering a subsystem) with nested default groups, lockdep raises a warning since it sees a lock recursion of class I_MUTEX_CHILD in populate_groups(). This patch makes such default groups creations lockdep-friendly by increasing the i_mutex sub-class from I_MUTEX_CHILD onwards when descending the default groups tree. With this patch the depth of default group trees is limited to MAX_LOCKDEP_SUBCLASSES - I_MUTEX_CHILD - 1 == 3. This limit is removed when not compiling lockdep. Signed-off-by: Louis Rilling --- fs/configfs/configfs_internal.h | 3 + fs/configfs/dir.c | 61 ++++++++++++++++++++++++++++++++++------ fs/configfs/mount.c | 3 + 3 files changed, 59 insertions(+), 8 deletions(-) Index: b/fs/configfs/configfs_internal.h =================================================================== --- a/fs/configfs/configfs_internal.h 2008-05-21 09:40:25.000000000 +0200 +++ b/fs/configfs/configfs_internal.h 2008-05-22 12:38:02.000000000 +0200 @@ -38,6 +38,9 @@ struct configfs_dirent { umode_t s_mode; struct dentry * s_dentry; struct iattr * s_iattr; +#ifdef CONFIG_LOCKDEP + int s_lock_level; +#endif }; #define CONFIGFS_ROOT 0x0001 Index: b/fs/configfs/dir.c =================================================================== --- a/fs/configfs/dir.c 2008-05-21 09:40:25.000000000 +0200 +++ b/fs/configfs/dir.c 2008-05-22 12:59:23.000000000 +0200 @@ -36,6 +36,37 @@ DECLARE_RWSEM(configfs_rename_sem); +#ifdef CONFIG_LOCKDEP +static inline int set_dirent_lock_level(struct configfs_dirent *prev_sd, + struct configfs_dirent *sd) +{ + int lock_level = prev_sd->s_lock_level + 1; + if (lock_level + I_MUTEX_CHILD < MAX_LOCKDEP_SUBCLASSES) { + sd->s_lock_level = lock_level; + return lock_level; + } + sd->s_lock_level = -1; + return -ELOOP; +} + +static inline void reset_dirent_lock_level(struct configfs_dirent *sd) +{ + sd->s_lock_level = -1; +} + +#else /* CONFIG_LOCKDEP */ + +static inline int set_dirent_lock_level(struct configfs_dirent *prev_sd, + struct configfs_dirent *sd) +{ + return 0; +} + +static inline void reset_dirent_lock_level(struct configfs_dirent *sd) +{ +} +#endif /* CONFIG_LOCKDEP */ + static void configfs_d_iput(struct dentry * dentry, struct inode * inode) { @@ -533,6 +564,10 @@ static int populate_groups(struct config { struct config_group *new_group; struct dentry *dentry = group->cg_item.ci_dentry; + struct configfs_dirent *sd = dentry->d_fsdata; + struct configfs_dirent *parent_sd = + group->cg_item.ci_parent->ci_dentry->d_fsdata; + int lock_level; int ret = 0; int i; @@ -546,17 +581,27 @@ static int populate_groups(struct config * That said, taking our i_mutex is closer to mkdir * emulation, and shouldn't hurt. */ - mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD); + /* lock_level starts at zero for the non default group */ + lock_level = set_dirent_lock_level(parent_sd, sd); + if (lock_level < 0) { + /* Too deeply nested default groups */ + ret = lock_level; + } else { + mutex_lock_nested(&dentry->d_inode->i_mutex, + I_MUTEX_CHILD + lock_level); - for (i = 0; group->default_groups[i]; i++) { - new_group = group->default_groups[i]; + for (i = 0; group->default_groups[i]; i++) { + new_group = group->default_groups[i]; - ret = create_default_group(group, new_group); - if (ret) - break; - } + ret = create_default_group(group, new_group); + if (ret) + break; + } - mutex_unlock(&dentry->d_inode->i_mutex); + mutex_unlock(&dentry->d_inode->i_mutex); + /* Reset for future sub-group creations */ + reset_dirent_lock_level(sd); + } } if (ret) Index: b/fs/configfs/mount.c =================================================================== --- a/fs/configfs/mount.c 2008-05-21 09:40:25.000000000 +0200 +++ b/fs/configfs/mount.c 2008-05-22 12:38:02.000000000 +0200 @@ -64,6 +64,9 @@ static struct configfs_dirent configfs_r .s_element = &configfs_root_group.cg_item, .s_type = CONFIGFS_ROOT, .s_iattr = NULL, +#ifdef CONFIG_LOCKDEP + .s_lock_level = -1, +#endif }; static int configfs_fill_super(struct super_block *sb, void *data, int silent) -- Dr Louis Rilling Kerlabs Skype: louis.rilling Batiment Germanium Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes http://www.kerlabs.com/ 35700 Rennes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/