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mac80211: make scan_sdata pointer usable with RCU
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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@intel.com>
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@jmberg-intel
jmberg-intel committed Jul 12, 2012
1 parent d811b3d commit e2fd5db
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Showing 3 changed files with 30 additions and 14 deletions.
2 changes: 1 addition & 1 deletion net/mac80211/ieee80211_i.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -972,7 +972,7 @@ 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;

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9 changes: 5 additions & 4 deletions net/mac80211/iface.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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) {
Expand Down Expand Up @@ -628,7 +629,7 @@ 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);

/*
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33 changes: 24 additions & 9 deletions net/mac80211/scan.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -293,7 +293,13 @@ 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;
}
Expand Down Expand Up @@ -394,7 +400,10 @@ 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,
Expand All @@ -405,9 +414,12 @@ 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,
Expand Down Expand Up @@ -439,7 +451,7 @@ 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;
}

Expand Down Expand Up @@ -473,7 +485,7 @@ 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);
Expand Down Expand Up @@ -533,7 +545,7 @@ 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;
Expand Down Expand Up @@ -720,7 +732,8 @@ 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)) {
Expand All @@ -741,7 +754,7 @@ 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) {
Expand Down Expand Up @@ -893,7 +906,9 @@ 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;
}

Expand Down

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