Messages in this thread | | | Date | Mon, 24 Mar 2014 07:11:44 -0400 | From | Neil Horman <> | Subject | Re: [PATCH] net/core: Use RCU_INIT_POINTER(x, NULL) in netpoll.c |
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On Mon, Mar 24, 2014 at 12:42:46AM +0530, Monam Agarwal wrote: > This patch replaces rcu_assign_pointer(x, NULL) with RCU_INIT_POINTER(x, NULL) > > The rcu_assign_pointer() ensures that the initialization of a structure > is carried out before storing a pointer to that structure. > And in the case of the NULL pointer, there is no structure to initialize. > So, rcu_assign_pointer(p, NULL) can be safely converted to RCU_INIT_POINTER(p, NULL) > > Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com> No, I don't think this is right. __netpoll_cleanup can be called in parallel with bottom half access to dev->npinfo. rcu_assign pointer is safe against those accesses, but RCU_INIT_POINTER is not.
Neil
> --- > net/core/netpoll.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/core/netpoll.c b/net/core/netpoll.c > index 7291dde..41c4e9c 100644 > --- a/net/core/netpoll.c > +++ b/net/core/netpoll.c > @@ -809,7 +809,7 @@ void __netpoll_cleanup(struct netpoll *np) > if (ops->ndo_netpoll_cleanup) > ops->ndo_netpoll_cleanup(np->dev); > > - rcu_assign_pointer(np->dev->npinfo, NULL); > + RCU_INIT_POINTER(np->dev->npinfo, NULL); > call_rcu_bh(&npinfo->rcu, rcu_cleanup_netpoll_info); > } > } > -- > 1.7.9.5 > >
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