mac80211: document sleep requirements for channel context ops

Channel context driver operations can sleep, so add might_sleep()
and document this.

Signed-off-by: Chaitanya T K <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

include/net/mac80211.h

···
  *	The callback is optional and can sleep.
  *
  * @add_chanctx: Notifies device driver about new channel context creation.
+ *	This callback may sleep.
  * @remove_chanctx: Notifies device driver about channel context destruction.
+ *	This callback may sleep.
  * @change_chanctx: Notifies device driver about channel context changes that
  *	may happen when combining different virtual interfaces on the same
  *	channel context with different settings
+ *	This callback may sleep.
  * @assign_vif_chanctx: Notifies device driver about channel context being bound
  *	to vif. Possible use is for hw queue remapping.
+ *	This callback may sleep.
  * @unassign_vif_chanctx: Notifies device driver about channel context being
  *	unbound from vif.
+ *	This callback may sleep.
  * @switch_vif_chanctx: switch a number of vifs from one chanctx to
  *	another, as specified in the list of
  *	@ieee80211_vif_chanctx_switch passed to the driver, according
  *	to the mode defined in &ieee80211_chanctx_switch_mode.
+ *	This callback may sleep.
  *
  * @start_ap: Start operation on the AP interface, this is called after all the
  *	information in bss_conf is set and beacon can be retrieved. A channel

net/mac80211/driver-ops.c

···
 	int ret = 0;
 	int i;
 
+	might_sleep();
+
 	if (!local->ops->switch_vif_chanctx)
 		return -EOPNOTSUPP;
 

net/mac80211/driver-ops.h

···
 {
 	int ret = -EOPNOTSUPP;
 
+	might_sleep();
+
 	trace_drv_add_chanctx(local, ctx);
 	if (local->ops->add_chanctx)
 		ret = local->ops->add_chanctx(&local->hw, &ctx->conf);
···
 static inline void drv_remove_chanctx(struct ieee80211_local *local,
 				      struct ieee80211_chanctx *ctx)
 {
+	might_sleep();
+
 	if (WARN_ON(!ctx->driver_present))
 		return;
 
···
 				      struct ieee80211_chanctx *ctx,
 				      u32 changed)
 {
+	might_sleep();
+
 	trace_drv_change_chanctx(local, ctx, changed);
 	if (local->ops->change_chanctx) {
 		WARN_ON_ONCE(!ctx->driver_present);
···
 					    struct ieee80211_sub_if_data *sdata,
 					    struct ieee80211_chanctx *ctx)
 {
+	might_sleep();
+
 	if (!check_sdata_in_driver(sdata))
 		return;
 
···
 			       struct ieee80211_sub_if_data *sdata)
 {
 	int ret = 0;
+
+	might_sleep();
 
 	if (!check_sdata_in_driver(sdata))
 		return -EIO;