From: Johannes Berg <johannes.berg@xxxxxxxxx>
Making the scan_sdata pointer usable with RCU makes
it possible to dereference it in the RX path to see
if a received frame actually matches the interface
that is scanning. This is just preparations, making
the pointer __rcu.
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
net/mac80211/ieee80211_i.h | 2 +-
net/mac80211/iface.c | 9 +++++----
net/mac80211/scan.c | 33 ++++++++++++++++++++++++---------
3 files changed, 30 insertions(+), 14 deletions(-)
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index b0830ae..da66a73 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -974,7 +974,7 @@ struct ieee80211_local {
unsigned long leave_oper_channel_time;
enum mac80211_scan_state next_scan_state;
struct delayed_work scan_work;
- struct ieee80211_sub_if_data *scan_sdata;
+ struct ieee80211_sub_if_data __rcu *scan_sdata;
enum nl80211_channel_type _oper_channel_type;
struct ieee80211_channel *oper_channel, *csa_channel;
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index c4c20cf7..43e1052 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -112,10 +112,11 @@ static u32 __ieee80211_recalc_idle(struct ieee80211_local *local)
}
}
- if (local->scan_sdata &&
- !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) {
+ sdata = rcu_dereference_protected(local->scan_sdata,
+ lockdep_is_held(&local->mtx));
+ if (sdata && !(local->hw.flags & IEEE80211_HW_SCAN_WHILE_IDLE)) {
scanning = true;
- local->scan_sdata->vif.bss_conf.idle = false;
+ sdata->vif.bss_conf.idle = false;
}
list_for_each_entry(sdata, &local->interfaces, list) {
@@ -636,7 +637,7 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
clear_bit(SDATA_STATE_RUNNING, &sdata->state);
- if (local->scan_sdata == sdata)
+ if (rcu_access_pointer(local->scan_sdata) == sdata)
ieee80211_scan_cancel(local);
/*
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index d1b4b9d..48d3219 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -294,7 +294,13 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
return;
if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
- int rc = drv_hw_scan(local, local->scan_sdata, local->hw_scan_req);
+ int rc;
+
+ rc = drv_hw_scan(local,
+ rcu_dereference_protected(local->scan_sdata,
+ lockdep_is_held(&local->mtx)),
+ local->hw_scan_req);
+
if (rc == 0)
return;
}
@@ -395,7 +401,10 @@ void ieee80211_run_deferred_scan(struct ieee80211_local *local)
if (!local->scan_req || local->scanning)
return;
- if (!ieee80211_can_scan(local, local->scan_sdata))
+ if (!ieee80211_can_scan(local,
+ rcu_dereference_protected(
+ local->scan_sdata,
+ lockdep_is_held(&local->mtx))))
return;
ieee80211_queue_delayed_work(&local->hw, &local->scan_work,
@@ -406,9 +415,12 @@ static void ieee80211_scan_state_send_probe(struct ieee80211_local *local,
unsigned long *next_delay)
{
int i;
- struct ieee80211_sub_if_data *sdata = local->scan_sdata;
+ struct ieee80211_sub_if_data *sdata;
enum ieee80211_band band = local->hw.conf.channel->band;
+ sdata = rcu_dereference_protected(local->scan_sdata,
+ lockdep_is_held(&local->mtx));;
+
for (i = 0; i < local->scan_req->n_ssids; i++)
ieee80211_send_probe_req(
sdata, NULL,
@@ -440,7 +452,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
if (!ieee80211_can_scan(local, sdata)) {
/* wait for the work to finish/time out */
local->scan_req = req;
- local->scan_sdata = sdata;
+ rcu_assign_pointer(local->scan_sdata, sdata);
return 0;
}
@@ -474,7 +486,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
}
local->scan_req = req;
- local->scan_sdata = sdata;
+ rcu_assign_pointer(local->scan_sdata, sdata);
if (local->ops->hw_scan) {
__set_bit(SCAN_HW_SCANNING, &local->scanning);
@@ -534,7 +546,7 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
ieee80211_recalc_idle(local);
local->scan_req = NULL;
- local->scan_sdata = NULL;
+ rcu_assign_pointer(local->scan_sdata, NULL);
}
return rc;
@@ -721,7 +733,8 @@ void ieee80211_scan_work(struct work_struct *work)
mutex_lock(&local->mtx);
- sdata = local->scan_sdata;
+ sdata = rcu_dereference_protected(local->scan_sdata,
+ lockdep_is_held(&local->mtx));
/* When scanning on-channel, the first-callback means completed. */
if (test_bit(SCAN_ONCHANNEL_SCANNING, &local->scanning)) {
@@ -742,7 +755,7 @@ void ieee80211_scan_work(struct work_struct *work)
int rc;
local->scan_req = NULL;
- local->scan_sdata = NULL;
+ rcu_assign_pointer(local->scan_sdata, NULL);
rc = __ieee80211_start_scan(sdata, req);
if (rc) {
@@ -894,7 +907,9 @@ void ieee80211_scan_cancel(struct ieee80211_local *local)
if (test_bit(SCAN_HW_SCANNING, &local->scanning)) {
if (local->ops->cancel_hw_scan)
- drv_cancel_hw_scan(local, local->scan_sdata);
+ drv_cancel_hw_scan(local,
+ rcu_dereference_protected(local->scan_sdata,
+ lockdep_is_held(&local->mtx)));
goto out;
}
--
1.7.10.4
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