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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: Lior Cohen <lior2.cohen@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/20190830112451.21655-7-luca@coelho.fi
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Lior Cohen 2019-08-30 14:24:49 +03:00 committed by Johannes Berg
parent 1c9559734e
commit 624ff4b210
3 changed files with 15 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
net/mac80211/key.c
View File

@ -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);
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(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;
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)
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);

4
net/mac80211/key.h
View File

@ -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)))

6
net/mac80211/util.c
View File

@ -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);