On Thu, Apr 18, 2013 at 06:04:43PM -0400, Bob Copeland wrote:
> The RCU docs used to state that rcu_barrier() included a wait
> for an RCU grace period; however the comments for rcu_barrier()
> as of commit f0a0e6f... "rcu: Clarify memory-ordering properties
> of grace-period primitives" contradict this.
>
> So add back synchronize_{rcu,net}() to where they once were,
> but keep the rcu_barrier()s for the call_rcu() callbacks.
>
> Cc: stable <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Bob Copeland <bob@xxxxxxxxxxx>
Reviewed-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> ---
> net/mac80211/iface.c | 5 +++--
> net/mac80211/pm.c | 1 +
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
> index b6abaaa..c634aff 100644
> --- a/net/mac80211/iface.c
> +++ b/net/mac80211/iface.c
> @@ -836,11 +836,12 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
> *
> * sta_info_flush_cleanup() requires rcu_barrier()
> * first to wait for the station call_rcu() calls
> - * to complete, here we need at least sychronize_rcu()
> - * it to wait for the RX path in case it is using the
> + * to complete, and we also need synchronize_rcu()
> + * to wait for the RX path in case it is using the
> * interface and enqueuing frames at this very time on
> * another CPU.
> */
> + synchronize_rcu();
> rcu_barrier();
> sta_info_flush_cleanup(sdata);
>
> diff --git a/net/mac80211/pm.c b/net/mac80211/pm.c
> index 4431f0f..7fc5d0d 100644
> --- a/net/mac80211/pm.c
> +++ b/net/mac80211/pm.c
> @@ -38,6 +38,7 @@ int __ieee80211_suspend(struct ieee80211_hw *hw, struct cfg80211_wowlan *wowlan)
> IEEE80211_QUEUE_STOP_REASON_SUSPEND);
>
> /* flush out all packets and station cleanup call_rcu()s */
> + synchronize_net();
> rcu_barrier();
>
> ieee80211_flush_queues(local, NULL);
> --
> 1.7.10.4
>
> --
> Bob Copeland %% www.bobcopeland.com
>
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