On Tue, Oct 23, 2012 at 11:55 AM, Thomas Pedersen <thomas@xxxxxxxxxxx> wrote:
> mesh_plink_alloc() was being called with the RCU read lock held, which
> triggered warnings because various things inside this function must
> sleep. It doesn't make much sense to hold an RCU lock on a pointer we
> don't yet have anyway, so do rcu_read_unlock() if allocating and relock
> on insertion. This also means there is no need for
> cfg80211_notify_new_peer_candidate() to be atomic.
>
> Also balance the RCU lock if we are returning early.
>
> This warning was only visible with CONFIG_DEBUG_ATOMIC_SLEEP enabled.
>
> Reported-by: Bob Copeland <me@xxxxxxxxxxxxxxx>
> Signed-off-by: Thomas Pedersen <thomas@xxxxxxxxxxx>
Reviewed-by: Javier Cardona <javier@xxxxxxxxxxx>
Javier
> ---
> net/mac80211/mesh_plink.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/net/mac80211/mesh_plink.c b/net/mac80211/mesh_plink.c
> index 234fe75..427c87d 100644
> --- a/net/mac80211/mesh_plink.c
> +++ b/net/mac80211/mesh_plink.c
> @@ -346,7 +346,7 @@ static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,
> enum ieee80211_band band = ieee80211_get_sdata_band(sdata);
> struct ieee80211_supported_band *sband;
> u32 rates, basic_rates = 0;
> - struct sta_info *sta;
> + struct sta_info *sta = NULL;
> bool insert = false;
>
> sband = local->hw.wiphy->bands[band];
> @@ -354,18 +354,19 @@ static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,
>
> sta = sta_info_get(sdata, addr);
> if (!sta) {
> + rcu_read_unlock();
> /* Userspace handles peer allocation when security is enabled */
> if (sdata->u.mesh.security & IEEE80211_MESH_SEC_AUTHED) {
> cfg80211_notify_new_peer_candidate(sdata->dev, addr,
> elems->ie_start,
> elems->total_len,
> - GFP_ATOMIC);
> - return NULL;
> + GFP_KERNEL);
> + goto lock_out;
> }
>
> sta = mesh_plink_alloc(sdata, addr);
> if (!sta)
> - return NULL;
> + goto lock_out;
> insert = true;
> }
>
> @@ -397,10 +398,13 @@ static struct sta_info *mesh_peer_init(struct ieee80211_sub_if_data *sdata,
> rate_control_rate_init(sta);
> spin_unlock_bh(&sta->lock);
>
> - if (insert && sta_info_insert(sta))
> + if (insert && sta_info_insert_rcu(sta))
> return NULL;
>
> return sta;
> +lock_out:
> + rcu_read_lock();
> + return sta;
> }
>
> void mesh_neighbour_update(struct ieee80211_sub_if_data *sdata,
> --
> 1.7.9.5
>
> _______________________________________________
> Devel mailing list
> Devel@xxxxxxxxxxxxxxxxxxxx
> http://lists.open80211s.org/cgi-bin/mailman/listinfo/devel
--
Javier Cardona
cozybit Inc.
http://www.cozybit.com
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