Message ID | 1363381993-31496-2-git-send-email-greearb@candelatech.com (mailing list archive) |
---|---|
State | Not Applicable, archived |
Headers | show |
On Fri, 2013-03-15 at 14:13 -0700, greearb@candelatech.com wrote: > --- a/net/mac80211/ieee80211_i.h > +++ b/net/mac80211/ieee80211_i.h > @@ -669,6 +669,12 @@ struct ieee80211_sub_if_data { > /* count for keys needing tailroom space allocation */ > int crypto_tx_tailroom_needed_cnt; > > + /* A pointer to some station associated with this interface, or > + * NULL. This aids oportunistic lookup for sta_info objects when typo: opportunistic. Also it should probably say "allows opportunistic lookup" :-) > + /* Shortcut for finding station entries when sdata is a station */ > + some_sta = rcu_dereference(sdata->some_sta); > + if (some_sta) { > + if (WARN_ON(some_sta->sdata != sdata)) > + rcu_assign_pointer(sdata->some_sta, NULL); > + else > + if (ether_addr_equal(some_sta->sta.addr, addr)) > + return some_sta; I worry a little bit about the overhead in the "always cache miss" case. Is this really helpful for AP interfaces? Maybe it should be limited to managed virtual interfaces. > > sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)], > lockdep_is_held(&local->sta_mtx)); > @@ -263,10 +273,14 @@ struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata, > */ > void sta_info_free(struct ieee80211_local *local, struct sta_info *sta) > { > + struct sta_info* some_sta; > if (sta->rate_ctrl) missing blank line > rate_control_free_sta(sta); > > sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr); > + some_sta = rcu_dereference(sta->sdata->some_sta); > + if (some_sta == sta) > + rcu_assign_pointer(sta->sdata->some_sta, NULL); This clearing is WAY too late. You can look up the station way after you must be allowed to, this will invariably crash eventually. It absolutely must be when the station is unhashed, not when it's freed. > @@ -373,6 +387,8 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata, > for (i = 0; i < NUM_RX_DATA_QUEUES; i++) > sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX); > > + rcu_assign_pointer(sta->sdata->some_sta, sta); This is too early, the station might not even be used, this must only be done when the station is hashed. johannes -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 03/19/2013 01:12 PM, Johannes Berg wrote: > On Fri, 2013-03-15 at 14:13 -0700, greearb@candelatech.com wrote: > >> --- a/net/mac80211/ieee80211_i.h >> +++ b/net/mac80211/ieee80211_i.h >> @@ -669,6 +669,12 @@ struct ieee80211_sub_if_data { >> /* count for keys needing tailroom space allocation */ >> int crypto_tx_tailroom_needed_cnt; >> >> + /* A pointer to some station associated with this interface, or >> + * NULL. This aids oportunistic lookup for sta_info objects when > > typo: opportunistic. Also it should probably say "allows opportunistic > lookup" :-) > >> + /* Shortcut for finding station entries when sdata is a station */ >> + some_sta = rcu_dereference(sdata->some_sta); >> + if (some_sta) { >> + if (WARN_ON(some_sta->sdata != sdata)) >> + rcu_assign_pointer(sdata->some_sta, NULL); >> + else >> + if (ether_addr_equal(some_sta->sta.addr, addr)) >> + return some_sta; > > I worry a little bit about the overhead in the "always cache miss" case. > Is this really helpful for AP interfaces? Maybe it should be limited to > managed virtual interfaces. This was a quick fix that resolved the issue I was seeing, but I am now thinking that maybe a full hash based on local MAC instead of remote MAC should be added. In some code (station TX) we can use that hash, and we could also use it on RX when trying to find the sdata that a non-multicast packet is destined for. For other uses, the existing hash on the remote MAC address would remain the preferred lookup. The RX logic might still be tricky...not sure if we really need to pass all packets to PROMISC interfaces, nor sure when we could safely not fan-out non-data packets. >> sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr); >> + some_sta = rcu_dereference(sta->sdata->some_sta); >> + if (some_sta == sta) >> + rcu_assign_pointer(sta->sdata->some_sta, NULL); > > This clearing is WAY too late. You can look up the station way after you > must be allowed to, this will invariably crash eventually. It absolutely > must be when the station is unhashed, not when it's freed. > >> @@ -373,6 +387,8 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata, >> for (i = 0; i < NUM_RX_DATA_QUEUES; i++) >> sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX); >> >> + rcu_assign_pointer(sta->sdata->some_sta, sta); > > This is too early, the station might not even be used, this must only be > done when the station is hashed. Ok, I'll work on that. Thanks, Ben > > johannes >
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c index a618bda..5288a4f 100644 --- a/net/mac80211/cfg.c +++ b/net/mac80211/cfg.c @@ -1287,6 +1287,7 @@ static int ieee80211_change_station(struct wiphy *wiphy, if (params->vlan && params->vlan != sta->sdata->dev) { bool prev_4addr = false; bool new_4addr = false; + struct sta_info *some_sta; vlansdata = IEEE80211_DEV_TO_SUB_IF(params->vlan); @@ -1312,7 +1313,11 @@ static int ieee80211_change_station(struct wiphy *wiphy, prev_4addr = true; } + some_sta = rcu_dereference(sta->sdata->some_sta); + if (some_sta == sta) + rcu_assign_pointer(sta->sdata->some_sta, NULL); sta->sdata = vlansdata; + rcu_assign_pointer(sta->sdata->some_sta, sta); if (sta->sta_state == IEEE80211_STA_AUTHORIZED && prev_4addr != new_4addr) { diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index 493e2e8..fe5d35b 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -669,6 +669,12 @@ struct ieee80211_sub_if_data { /* count for keys needing tailroom space allocation */ int crypto_tx_tailroom_needed_cnt; + /* A pointer to some station associated with this interface, or + * NULL. This aids oportunistic lookup for sta_info objects when + * sdata is a station with a single sta_info. + */ + struct sta_info __rcu *some_sta; + struct net_device *dev; struct ieee80211_local *local; diff --git a/net/mac80211/sta_info.c b/net/mac80211/sta_info.c index 415f9c6..74d58f4 100644 --- a/net/mac80211/sta_info.c +++ b/net/mac80211/sta_info.c @@ -193,7 +193,17 @@ struct sta_info *sta_info_get(struct ieee80211_sub_if_data *sdata, const u8 *addr) { struct ieee80211_local *local = sdata->local; - struct sta_info *sta; + struct sta_info *sta, *some_sta; + + /* Shortcut for finding station entries when sdata is a station */ + some_sta = rcu_dereference(sdata->some_sta); + if (some_sta) { + if (WARN_ON(some_sta->sdata != sdata)) + rcu_assign_pointer(sdata->some_sta, NULL); + else + if (ether_addr_equal(some_sta->sta.addr, addr)) + return some_sta; + } sta = rcu_dereference_check(local->sta_hash[STA_HASH(addr)], lockdep_is_held(&local->sta_mtx)); @@ -263,10 +273,14 @@ struct sta_info *sta_info_get_by_idx(struct ieee80211_sub_if_data *sdata, */ void sta_info_free(struct ieee80211_local *local, struct sta_info *sta) { + struct sta_info* some_sta; if (sta->rate_ctrl) rate_control_free_sta(sta); sta_dbg(sta->sdata, "Destroyed STA %pM\n", sta->sta.addr); + some_sta = rcu_dereference(sta->sdata->some_sta); + if (some_sta == sta) + rcu_assign_pointer(sta->sdata->some_sta, NULL); kfree(sta); } @@ -373,6 +387,8 @@ struct sta_info *sta_info_alloc(struct ieee80211_sub_if_data *sdata, for (i = 0; i < NUM_RX_DATA_QUEUES; i++) sta->last_seq_ctrl[i] = cpu_to_le16(USHRT_MAX); + rcu_assign_pointer(sta->sdata->some_sta, sta); + sta_dbg(sdata, "Allocated STA %pM\n", sta->sta.addr); #ifdef CONFIG_MAC80211_MESH