mac80211: add a single-transaction driver op to switch contexts

In some cases, when the driver is already using all the channel
contexts it can handle at once, we have to do an in-place switch
(ie. we cannot afford using an extra context temporarily for the
transaction).  But some drivers may not support switching the channel
context assigned to a vif on the fly (ie. without unassigning and
assigning it) while others may only work if the context is changed on
the fly, without unassigning it first.

To allow these different scenarios, add a new driver operation that
let's the driver decide how to handle an in-place switch.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 138 insertions, 0 deletions

diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index 696ef78b1fb7..bd782dcffcc7 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -1048,6 +1048,59 @@ static inline void drv_unassign_vif_chanctx(struct ieee80211_local *local,
         trace_drv_return_void(local);
 }
 
+static inline int
+drv_switch_vif_chanctx(struct ieee80211_local *local,
+                       struct ieee80211_vif_chanctx_switch *vifs,
+                       int n_vifs,
+                       enum ieee80211_chanctx_switch_mode mode)
+{
+        int ret = 0;
+        int i;
+
+        if (!local->ops->switch_vif_chanctx)
+                return -EOPNOTSUPP;
+
+        for (i = 0; i < n_vifs; i++) {
+                struct ieee80211_chanctx *new_ctx =
+                        container_of(vifs[i].new_ctx,
+                                     struct ieee80211_chanctx,
+                                     conf);
+                struct ieee80211_chanctx *old_ctx =
+                        container_of(vifs[i].old_ctx,
+                                     struct ieee80211_chanctx,
+                                     conf);
+
+                WARN_ON_ONCE(!old_ctx->driver_present);
+                WARN_ON_ONCE((mode == CHANCTX_SWMODE_SWAP_CONTEXTS &&
+                              new_ctx->driver_present) ||
+                             (mode == CHANCTX_SWMODE_REASSIGN_VIF &&
+                              !new_ctx->driver_present));
+        }
+
+        trace_drv_switch_vif_chanctx(local, vifs, n_vifs, mode);
+        ret = local->ops->switch_vif_chanctx(&local->hw,
+                                             vifs, n_vifs, mode);
+        trace_drv_return_int(local, ret);
+
+        if (!ret && mode == CHANCTX_SWMODE_SWAP_CONTEXTS) {
+                for (i = 0; i < n_vifs; i++) {
+                        struct ieee80211_chanctx *new_ctx =
+                                container_of(vifs[i].new_ctx,
+                                             struct ieee80211_chanctx,
+                                             conf);
+                        struct ieee80211_chanctx *old_ctx =
+                                container_of(vifs[i].old_ctx,
+                                             struct ieee80211_chanctx,
+                                             conf);
+
+                        new_ctx->driver_present = true;
+                        old_ctx->driver_present = false;
+                }
+        }
+
+        return ret;
+}
+
 static inline int drv_start_ap(struct ieee80211_local *local,
                                struct ieee80211_sub_if_data *sdata)
 {
diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
index 942f64b8ce0e..b22d6969cde9 100644
--- a/net/mac80211/trace.h
+++ b/net/mac80211/trace.h
@@ -1389,6 +1389,91 @@ TRACE_EVENT(drv_change_chanctx,
         )
 );
 
+#if !defined(__TRACE_VIF_ENTRY)
+#define __TRACE_VIF_ENTRY
+struct trace_vif_entry {
+        enum nl80211_iftype vif_type;
+        bool p2p;
+        char vif_name[IFNAMSIZ];
+} __packed;
+
+struct trace_chandef_entry {
+        u32 control_freq;
+        u32 chan_width;
+        u32 center_freq1;
+        u32 center_freq2;
+} __packed;
+
+struct trace_switch_entry {
+        struct trace_vif_entry vif;
+        struct trace_chandef_entry old_chandef;
+        struct trace_chandef_entry new_chandef;
+} __packed;
+
+#define SWITCH_ENTRY_ASSIGN(to, from) local_vifs[i].to = vifs[i].from
+#endif
+
+TRACE_EVENT(drv_switch_vif_chanctx,
+        TP_PROTO(struct ieee80211_local *local,
+                 struct ieee80211_vif_chanctx_switch *vifs,
+                 int n_vifs, enum ieee80211_chanctx_switch_mode mode),
+            TP_ARGS(local, vifs, n_vifs, mode),
+
+        TP_STRUCT__entry(
+                LOCAL_ENTRY
+                __field(int, n_vifs)
+                __field(u32, mode)
+                __dynamic_array(u8, vifs,
+                                sizeof(struct trace_switch_entry) * n_vifs)
+        ),
+
+        TP_fast_assign(
+                LOCAL_ASSIGN;
+                __entry->n_vifs = n_vifs;
+                __entry->mode = mode;
+                {
+                        struct trace_switch_entry *local_vifs =
+                                __get_dynamic_array(vifs);
+                        int i;
+
+                        for (i = 0; i < n_vifs; i++) {
+                                struct ieee80211_sub_if_data *sdata;
+
+                                sdata = container_of(vifs[i].vif,
+                                                struct ieee80211_sub_if_data,
+                                                vif);
+
+                                SWITCH_ENTRY_ASSIGN(vif.vif_type, vif->type);
+                                SWITCH_ENTRY_ASSIGN(vif.p2p, vif->p2p);
+                                strncpy(local_vifs[i].vif.vif_name,
+                                        sdata->name,
+                                        sizeof(local_vifs[i].vif.vif_name));
+                                SWITCH_ENTRY_ASSIGN(old_chandef.control_freq,
+                                                old_ctx->def.chan->center_freq);
+                                SWITCH_ENTRY_ASSIGN(old_chandef.chan_width,
+                                                    old_ctx->def.width);
+                                SWITCH_ENTRY_ASSIGN(old_chandef.center_freq1,
+                                                    old_ctx->def.center_freq1);
+                                SWITCH_ENTRY_ASSIGN(old_chandef.center_freq2,
+                                                    old_ctx->def.center_freq2);
+                                SWITCH_ENTRY_ASSIGN(new_chandef.control_freq,
+                                                new_ctx->def.chan->center_freq);
+                                SWITCH_ENTRY_ASSIGN(new_chandef.chan_width,
+                                                    new_ctx->def.width);
+                                SWITCH_ENTRY_ASSIGN(new_chandef.center_freq1,
+                                                    new_ctx->def.center_freq1);
+                                SWITCH_ENTRY_ASSIGN(new_chandef.center_freq2,
+                                                    new_ctx->def.center_freq2);
+                        }
+                }
+        ),
+
+        TP_printk(
+                LOCAL_PR_FMT " n_vifs:%d mode:%d",
+                LOCAL_PR_ARG, __entry->n_vifs, __entry->mode
+        )
+);
+
 DECLARE_EVENT_CLASS(local_sdata_chanctx,
         TP_PROTO(struct ieee80211_local *local,
                  struct ieee80211_sub_if_data *sdata,