mac80211: add channel context iterator

Drivers may need to iterate the active channel
contexts, export an iterator function to allow
that. To make it possible, use RCU-safe list
functions.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 3560881d17eef8f2bd9da464aef1eda3751e5b04..f12df5bb529facf7daaca869c692283df735cd71 100644 (file)
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -3596,6 +3596,27 @@ void ieee80211_iter_keys(struct ieee80211_hw *hw,
                                      void *data),
                         void *iter_data);
 
+/**
+ * ieee80211_iter_chan_contexts_atomic - iterate channel contexts
+ * @hw: pointre obtained from ieee80211_alloc_hw().
+ * @iter: iterator function
+ * @iter_data: data passed to iterator function
+ *
+ * Iterate all active channel contexts. This function is atomic and
+ * doesn't acquire any locks internally that might be held in other
+ * places while calling into the driver.
+ *
+ * The iterator will not find a context that's being added (during
+ * the driver callback to add it) but will find it while it's being
+ * removed.
+ */
+void ieee80211_iter_chan_contexts_atomic(
+       struct ieee80211_hw *hw,
+       void (*iter)(struct ieee80211_hw *hw,
+                    struct ieee80211_chanctx_conf *chanctx_conf,
+                    void *data),
+       void *iter_data);
+
 /**
  * ieee80211_ap_probereq_get - retrieve a Probe Request template
  * @hw: pointer obtained from ieee80211_alloc_hw().

diff --git a/net/mac80211/chan.c b/net/mac80211/chan.c
index bfaa486d928ca9bed29854ac00963a7cd37c8779..f84b86028a9cd50bc95c10ec3410c4250c190eb1 100644 (file)
--- a/net/mac80211/chan.c
+++ b/net/mac80211/chan.c
@@ -3,6 +3,7 @@
  */
 
 #include <linux/nl80211.h>
+#include <linux/export.h>
 #include <net/cfg80211.h>
 #include "ieee80211_i.h"
 #include "driver-ops.h"
@@ -134,7 +135,7 @@ ieee80211_new_chanctx(struct ieee80211_local *local,
                }
        }
 
-       list_add(&ctx->list, &local->chanctx_list);
+       list_add_rcu(&ctx->list, &local->chanctx_list);
 
        return ctx;
 }
@@ -153,7 +154,7 @@ static void ieee80211_free_chanctx(struct ieee80211_local *local,
                drv_remove_chanctx(local, ctx);
        }
 
-       list_del(&ctx->list);
+       list_del_rcu(&ctx->list);
        kfree_rcu(ctx, rcu_head);
 }
 
@@ -379,3 +380,20 @@ void ieee80211_vif_release_channel(struct ieee80211_sub_if_data *sdata)
        __ieee80211_vif_release_channel(sdata);
        mutex_unlock(&sdata->local->chanctx_mtx);
 }
+
+void ieee80211_iter_chan_contexts_atomic(
+       struct ieee80211_hw *hw,
+       void (*iter)(struct ieee80211_hw *hw,
+                    struct ieee80211_chanctx_conf *chanctx_conf,
+                    void *data),
+       void *iter_data)
+{
+       struct ieee80211_local *local = hw_to_local(hw);
+       struct ieee80211_chanctx *ctx;
+
+       rcu_read_lock();
+       list_for_each_entry_rcu(ctx, &local->chanctx_list, list)
+               iter(hw, &ctx->conf, iter_data);
+       rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(ieee80211_iter_chan_contexts_atomic);