Re: fix rcu annotations noise in cred.h
From: Paul E. McKenney
Date: Mon Aug 08 2011 - 10:35:30 EST
On Mon, Aug 08, 2011 at 01:54:08PM +0100, David Howells wrote:
> Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> > This is indeed what rcu_dereference_protected() is intended for.
> How about the attached patch?
> From: David Howells <dhowells@xxxxxxxxxx>
> Subject: [PATCH] CRED: Restore const to current_cred()
> Commit 3295514841c2112d94451ba5deaf54f5afb78ea9 accidentally dropped the const
> of current->cred inside current_cred() by the insertion of a cast to deal with
> an RCU annotation loss warning from sparce.
> Use an appropriate RCU wrapper instead so as not to lose the const.
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> include/linux/cred.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
> diff --git a/include/linux/cred.h b/include/linux/cred.h
> index 98f46ef..8e2fd44 100644
> --- a/include/linux/cred.h
> +++ b/include/linux/cred.h
> @@ -269,7 +269,7 @@ static inline void put_cred(const struct cred *_cred)
> * since nobody else can modify it.
> #define current_cred() \
> - (*(__force struct cred **)¤t->cred)
> + rcu_dereference_protected(current->cred, 1)
> * __task_cred - Access a task's objective credentials
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