// SPDX-License-Identifier: GPL-2.0-only
/*
 * MLO link handling
 *
 * Copyright (C) 2022 Intel Corporation
 */
#include <linux/slab.h>
#include <linux/kernel.h>
#include <net/mac80211.h>
#include "ieee80211_i.h"
#include "driver-ops.h"

void ieee80211_link_setup(struct ieee80211_link_data *link)
{
	if (link->sdata->vif.type == NL80211_IFTYPE_STATION)
		ieee80211_mgd_setup_link(link);
}

void ieee80211_link_init(struct ieee80211_sub_if_data *sdata,
			 int link_id,
			 struct ieee80211_link_data *link,
			 struct ieee80211_bss_conf *link_conf)
{
	bool deflink = link_id < 0;

	if (link_id < 0)
		link_id = 0;

	rcu_assign_pointer(sdata->vif.link_conf[link_id], link_conf);
	rcu_assign_pointer(sdata->link[link_id], link);

	link->sdata = sdata;
	link->link_id = link_id;
	link->conf = link_conf;
	link_conf->link_id = link_id;

	INIT_WORK(&link->csa_finalize_work,
		  ieee80211_csa_finalize_work);
	INIT_WORK(&link->color_change_finalize_work,
		  ieee80211_color_change_finalize_work);
	INIT_LIST_HEAD(&link->assigned_chanctx_list);
	INIT_LIST_HEAD(&link->reserved_chanctx_list);
	INIT_DELAYED_WORK(&link->dfs_cac_timer_work,
			  ieee80211_dfs_cac_timer_work);

	if (!deflink) {
		switch (sdata->vif.type) {
		case NL80211_IFTYPE_AP:
			ether_addr_copy(link_conf->addr,
					sdata->wdev.links[link_id].addr);
			link_conf->bssid = link_conf->addr;
			WARN_ON(!(sdata->wdev.valid_links & BIT(link_id)));
			break;
		case NL80211_IFTYPE_STATION:
			/* station sets the bssid in ieee80211_mgd_setup_link */
			break;
		default:
			WARN_ON(1);
		}
	}
}

void ieee80211_link_stop(struct ieee80211_link_data *link)
{
	if (link->sdata->vif.type == NL80211_IFTYPE_STATION)
		ieee80211_mgd_stop_link(link);

	ieee80211_link_release_channel(link);
}

struct link_container {
	struct ieee80211_link_data data;
	struct ieee80211_bss_conf conf;
};

static void ieee80211_free_links(struct ieee80211_sub_if_data *sdata,
				 struct link_container **links)
{
	LIST_HEAD(keys);
	unsigned int link_id;

	for (link_id = 0; link_id < IEEE80211_MLD_MAX_NUM_LINKS; link_id++) {
		if (!links[link_id])
			continue;
		ieee80211_remove_link_keys(&links[link_id]->data, &keys);
	}

	synchronize_rcu();

	ieee80211_free_key_list(sdata->local, &keys);

	for (link_id = 0; link_id < IEEE80211_MLD_MAX_NUM_LINKS; link_id++) {
		if (!links[link_id])
			continue;
		ieee80211_link_stop(&links[link_id]->data);
		kfree(links[link_id]);
	}
}

static int ieee80211_check_dup_link_addrs(struct ieee80211_sub_if_data *sdata)
{
	unsigned int i, j;

	for (i = 0; i < IEEE80211_MLD_MAX_NUM_LINKS; i++) {
		struct ieee80211_link_data *link1;

		link1 = sdata_dereference(sdata->link[i], sdata);
		if (!link1)
			continue;
		for (j = i + 1; j < IEEE80211_MLD_MAX_NUM_LINKS; j++) {
			struct ieee80211_link_data *link2;

			link2 = sdata_dereference(sdata->link[j], sdata);
			if (!link2)
				continue;

			if (ether_addr_equal(link1->conf->addr,
					     link2->conf->addr))
				return -EALREADY;
		}
	}

	return 0;
}

static int ieee80211_vif_update_links(struct ieee80211_sub_if_data *sdata,
				      struct link_container **to_free,
				      u16 new_links)
{
	u16 old_links = sdata->vif.valid_links;
	unsigned long add = new_links & ~old_links;
	unsigned long rem = old_links & ~new_links;
	unsigned int link_id;
	int ret;
	struct link_container *links[IEEE80211_MLD_MAX_NUM_LINKS] = {}, *link;
	struct ieee80211_bss_conf *old[IEEE80211_MLD_MAX_NUM_LINKS];
	struct ieee80211_link_data *old_data[IEEE80211_MLD_MAX_NUM_LINKS];
	bool use_deflink = old_links == 0; /* set for error case */

	sdata_assert_lock(sdata);

	memset(to_free, 0, sizeof(links));

	if (old_links == new_links)
		return 0;

	/* if there were no old links, need to clear the pointers to deflink */
	if (!old_links)
		rem |= BIT(0);

	/* allocate new link structures first */
	for_each_set_bit(link_id, &add, IEEE80211_MLD_MAX_NUM_LINKS) {
		link = kzalloc(sizeof(*link), GFP_KERNEL);
		if (!link) {
			ret = -ENOMEM;
			goto free;
		}
		links[link_id] = link;
	}

	/* keep track of the old pointers for the driver */
	BUILD_BUG_ON(sizeof(old) != sizeof(sdata->vif.link_conf));
	memcpy(old, sdata->vif.link_conf, sizeof(old));
	/* and for us in error cases */
	BUILD_BUG_ON(sizeof(old_data) != sizeof(sdata->link));
	memcpy(old_data, sdata->link, sizeof(old_data));

	/* grab old links to free later */
	for_each_set_bit(link_id, &rem, IEEE80211_MLD_MAX_NUM_LINKS) {
		if (rcu_access_pointer(sdata->link[link_id]) != &sdata->deflink) {
			/*
			 * we must have allocated the data through this path so
			 * we know we can free both at the same time
			 */
			to_free[link_id] = container_of(rcu_access_pointer(sdata->link[link_id]),
							typeof(*links[link_id]),
							data);
		}

		RCU_INIT_POINTER(sdata->link[link_id], NULL);
		RCU_INIT_POINTER(sdata->vif.link_conf[link_id], NULL);
	}

	/* link them into data structures */
	for_each_set_bit(link_id, &add, IEEE80211_MLD_MAX_NUM_LINKS) {
		WARN_ON(!use_deflink &&
			rcu_access_pointer(sdata->link[link_id]) == &sdata->deflink);

		link = links[link_id];
		ieee80211_link_init(sdata, link_id, &link->data, &link->conf);
		ieee80211_link_setup(&link->data);
	}

	if (new_links == 0)
		ieee80211_link_init(sdata, -1, &sdata->deflink,
				    &sdata->vif.bss_conf);

	sdata->vif.valid_links = new_links;

	ret = ieee80211_check_dup_link_addrs(sdata);
	if (!ret) {
		/* tell the driver */
		ret = drv_change_vif_links(sdata->local, sdata,
					   old_links, new_links,
					   old);
	}

	if (ret) {
		/* restore config */
		memcpy(sdata->link, old_data, sizeof(old_data));
		memcpy(sdata->vif.link_conf, old, sizeof(old));
		sdata->vif.valid_links = old_links;
		/* and free (only) the newly allocated links */
		memset(to_free, 0, sizeof(links));
		goto free;
	}

	/* use deflink/bss_conf again if and only if there are no more links */
	use_deflink = new_links == 0;

	goto deinit;
free:
	/* if we failed during allocation, only free all */
	for (link_id = 0; link_id < IEEE80211_MLD_MAX_NUM_LINKS; link_id++) {
		kfree(links[link_id]);
		links[link_id] = NULL;
	}
deinit:
	if (use_deflink)
		ieee80211_link_init(sdata, -1, &sdata->deflink,
				    &sdata->vif.bss_conf);
	return ret;
}

int ieee80211_vif_set_links(struct ieee80211_sub_if_data *sdata,
			    u16 new_links)
{
	struct link_container *links[IEEE80211_MLD_MAX_NUM_LINKS];
	int ret;

	ret = ieee80211_vif_update_links(sdata, links, new_links);
	ieee80211_free_links(sdata, links);

	return ret;
}

void ieee80211_vif_clear_links(struct ieee80211_sub_if_data *sdata)
{
	struct link_container *links[IEEE80211_MLD_MAX_NUM_LINKS];

	/*
	 * The locking here is different because when we free links
	 * in the station case we need to be able to cancel_work_sync()
	 * something that also takes the lock.
	 */

	sdata_lock(sdata);
	ieee80211_vif_update_links(sdata, links, 0);
	sdata_unlock(sdata);

	ieee80211_free_links(sdata, links);
}