Messages in this thread Patch in this message | | | Date | Thu, 12 Jun 2008 17:26:48 +0200 | From | Louis Rilling <> | Subject | [RFC][PATCH 3/3] configfs: Protect configfs_dirent s_links list mutations |
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Symlinks to a config_item are listed under its configfs_dirent s_links, but the list mutations are not protected by any common lock.
This patch uses the configfs_dirent_lock spinlock to add the necessary protection.
Note: we should also protect the list_empty() test in configfs_detach_prep() but 1/ the lock should not be released immediately because nothing would prevent the list from being filled after a successful list_empty() test, making the problem tricky, 2/ this will be solved by the rmdir() vs rename() deadlock bugfix.
Signed-off-by: Louis Rilling <Louis.Rilling@kerlabs.com> --- fs/configfs/symlink.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
Index: b/fs/configfs/symlink.c =================================================================== --- a/fs/configfs/symlink.c 2008-06-12 16:50:40.000000000 +0200 +++ b/fs/configfs/symlink.c 2008-06-12 16:52:43.000000000 +0200 @@ -77,12 +77,15 @@ static int create_link(struct config_ite sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL); if (sl) { sl->sl_target = config_item_get(item); - /* FIXME: needs a lock, I'd bet */ + spin_lock(&configfs_dirent_lock); list_add(&sl->sl_list, &target_sd->s_links); + spin_unlock(&configfs_dirent_lock); ret = configfs_create_link(sl, parent_item->ci_dentry, dentry); if (ret) { + spin_lock(&configfs_dirent_lock); list_del_init(&sl->sl_list); + spin_unlock(&configfs_dirent_lock); config_item_put(item); kfree(sl); } @@ -190,8 +193,9 @@ int configfs_unlink(struct inode *dir, s type->ct_item_ops->drop_link(parent_item, sl->sl_target); - /* FIXME: Needs lock */ + spin_lock(&configfs_dirent_lock); list_del_init(&sl->sl_list); + spin_unlock(&configfs_dirent_lock); /* Put reference from create_link() */ config_item_put(sl->sl_target); -- 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
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