On Sun, Aug 07, 2011 at 11:22:51AM -0500, Steve French wrote: > I noticed a series of sparse warnings (on all calls to cifs's GetXid > after building on a newly install fc15 system (yum installed a sparse > binary dated June 23). > > fs/cifs/cifsfs.c:168:15: warning: dereference of noderef expression > fs/cifs/cifsfs.c:542:15: warning: dereference of noderef expression > > Has sparse changed to add a new warning - I see (from quick search) > others getting this on other modules years ago, but I didn't see > anything obvious wrong with the definition of the function, and I > hadn't noticed sparse complaining about it before, and would like to > remove the 50+ new messages as they clutter the build output.
It's not sparse change - the whinge comes from current_fsuid(), i.e. direct read of current->cred, even though it's declared with __rcu. The thing is, current->cred does *not* need rcu_dereference() - only the task itself can change it. Easily fixed... Signed-off-by: Al Viro <[email protected]> --- diff --git a/include/linux/cred.h b/include/linux/cred.h index 48e82af..98f46ef 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -265,10 +265,11 @@ static inline void put_cred(const struct cred *_cred) /** * current_cred - Access the current task's subjective credentials * - * Access the subjective credentials of the current task. + * Access the subjective credentials of the current task. RCU-safe, + * since nobody else can modify it. */ #define current_cred() \ - (current->cred) + (*(__force struct cred **)¤t->cred) /** * __task_cred - Access a task's objective credentials @@ -307,7 +308,7 @@ static inline void put_cred(const struct cred *_cred) ({ \ struct user_struct *__u; \ struct cred *__cred; \ - __cred = (struct cred *) current_cred(); \ + __cred = current_cred(); \ __u = get_uid(__cred->user); \ __u; \ }) @@ -322,7 +323,7 @@ static inline void put_cred(const struct cred *_cred) ({ \ struct group_info *__groups; \ struct cred *__cred; \ - __cred = (struct cred *) current_cred(); \ + __cred = current_cred(); \ __groups = get_group_info(__cred->group_info); \ __groups; \ }) @@ -341,7 +342,7 @@ static inline void put_cred(const struct cred *_cred) #define current_cred_xxx(xxx) \ ({ \ - current->cred->xxx; \ + current_cred()->xxx; \ }) #define current_uid() (current_cred_xxx(uid)) -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
