Commit 624ff4b2 authored by Lior Cohen's avatar Lior Cohen Committed by Johannes Berg
Browse files

mac80211: clear crypto tx tailroom counter upon keys enable 



In case we got a fw restart while roaming from encrypted AP to
non-encrypted one, we might end up with hitting a warning on the pending
counter crypto_tx_tailroom_pending_dec having a non-zero value.

The following comment taken from net/mac80211/key.c explains the rational
for the delayed tailroom needed:

	/*
	* The reason for the delayed tailroom needed decrementing is to
	* make roaming faster: during roaming, all keys are first deleted
	* and then new keys are installed. The first new key causes the
	* crypto_tx_tailroom_needed_cnt to go from 0 to 1, which invokes
	* the cost of synchronize_net() (which can be slow). Avoid this
	* by deferring the crypto_tx_tailroom_needed_cnt decrementing on
	* key removal for a while, so if we roam the value is larger than
	* zero and no 0->1 transition happens.
	*
	* The cost is that if the AP switching was from an AP with keys
	* to one without, we still allocate tailroom while it would no
	* longer be needed. However, in the typical (fast) roaming case
	* within an ESS this usually won't happen.
	*/

The next flow lead to the warning eventually reported as a bug:
1. Disconnect from encrypted AP
2. Set crypto_tx_tailroom_pending_dec = 1 for the key
3. Schedule work
4. Reconnect to non-encrypted AP
5. Add a new key, setting the tailroom counter = 1
6. Got FW restart while pending counter is set ---> hit the warning

While on it, the ieee80211_reset_crypto_tx_tailroom() func was merged into
its single caller ieee80211_reenable_keys (previously called
ieee80211_enable_keys). Also, we reset the crypto_tx_tailroom_pending_dec
and remove the counters warning as we just reset both.

Signed-off-by: default avatarLior Cohen <lior2.cohen@intel.com>
Signed-off-by: default avatarLuca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/20190830112451.21655-7-luca@coelho.fi


Signed-off-by: default avatarJohannes Berg <johannes.berg@intel.com>
parent 1c955973

net/mac80211/key.c

+12 −28
Original line number Diff line number Diff line
@@ -843,46 +843,30 @@ void ieee80211_key_free(struct ieee80211_key *key, bool delay_tailroom) 
	ieee80211_key_destroy(key, delay_tailroom);

}



void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata)

void ieee80211_reenable_keys(struct ieee80211_sub_if_data *sdata)

{

	struct ieee80211_key *key;

	struct ieee80211_sub_if_data *vlan;



	ASSERT_RTNL();



	if (WARN_ON(!ieee80211_sdata_running(sdata)))

		return;



	mutex_lock(&sdata->local->key_mtx);



	WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt ||

		     sdata->crypto_tx_tailroom_pending_dec);

	sdata->crypto_tx_tailroom_needed_cnt = 0;

	sdata->crypto_tx_tailroom_pending_dec = 0;



	if (sdata->vif.type == NL80211_IFTYPE_AP) {

		list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)

			WARN_ON_ONCE(vlan->crypto_tx_tailroom_needed_cnt ||

				     vlan->crypto_tx_tailroom_pending_dec);

		list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list) {

			vlan->crypto_tx_tailroom_needed_cnt = 0;

			vlan->crypto_tx_tailroom_pending_dec = 0;

		}

	}



	if (ieee80211_sdata_running(sdata)) {

		list_for_each_entry(key, &sdata->key_list, list) {

			increment_tailroom_need_count(sdata);

			ieee80211_key_enable_hw_accel(key);

		}



	mutex_unlock(&sdata->local->key_mtx);

}



void ieee80211_reset_crypto_tx_tailroom(struct ieee80211_sub_if_data *sdata)

{

	struct ieee80211_sub_if_data *vlan;



	mutex_lock(&sdata->local->key_mtx);



	sdata->crypto_tx_tailroom_needed_cnt = 0;



	if (sdata->vif.type == NL80211_IFTYPE_AP) {

		list_for_each_entry(vlan, &sdata->u.ap.vlans, u.vlan.list)

			vlan->crypto_tx_tailroom_needed_cnt = 0;

	}



	mutex_unlock(&sdata->local->key_mtx);

net/mac80211/key.h

+2 −2
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
/*

 * Copyright 2002-2004, Instant802 Networks, Inc.

 * Copyright 2005, Devicescape Software, Inc.

 * Copyright (C) 2019 Intel Corporation

 */



#ifndef IEEE80211_KEY_H
@@ -156,8 +157,7 @@ void ieee80211_free_keys(struct ieee80211_sub_if_data *sdata, 
			 bool force_synchronize);

void ieee80211_free_sta_keys(struct ieee80211_local *local,

			     struct sta_info *sta);

void ieee80211_enable_keys(struct ieee80211_sub_if_data *sdata);

void ieee80211_reset_crypto_tx_tailroom(struct ieee80211_sub_if_data *sdata);

void ieee80211_reenable_keys(struct ieee80211_sub_if_data *sdata);



#define key_mtx_dereference(local, ref) \

	rcu_dereference_protected(ref, lockdep_is_held(&((local)->key_mtx)))

net/mac80211/util.c

+1 −5
Original line number Diff line number Diff line
@@ -2420,11 +2420,7 @@ int ieee80211_reconfig(struct ieee80211_local *local) 


	/* add back keys */

	list_for_each_entry(sdata, &local->interfaces, list)

		ieee80211_reset_crypto_tx_tailroom(sdata);



	list_for_each_entry(sdata, &local->interfaces, list)

		if (ieee80211_sdata_running(sdata))

			ieee80211_enable_keys(sdata);

		ieee80211_reenable_keys(sdata);



	/* Reconfigure sched scan if it was interrupted by FW restart */

	mutex_lock(&local->mtx);

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