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mac80211: keep lock when calling __ieee80211_scan_completed() 

We are taking local->mtx inside __ieee80211_scan_completed(), but just
before call to that function we drop the lock. Dropping/taking lock is not
good, because can lead to hard to understand race conditions.

Patch split scan_completed() code into two functions, first must be called
with local->mtx taken and second without it.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Stanislaw Gruszka 2010-10-06 11:22:09 +02:00 committed by John W. Linville
parent 259b62e35b
commit e229f844d7
1 changed files with 39 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

75
net/mac80211/scan.c
View File

@ -249,12 +249,12 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
return true;
}
static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
static bool __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted,
bool was_hw_scan)
{
struct ieee80211_local *local = hw_to_local(hw);
bool was_hw_scan;
mutex_lock(&local->mtx);
lockdep_assert_held(&local->mtx);
/*
* It's ok to abort a not-yet-running scan (that
@ -265,17 +265,13 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
if (WARN_ON(!local->scanning && !aborted))
aborted = true;
if (WARN_ON(!local->scan_req)) {
mutex_unlock(&local->mtx);
return;
}
if (WARN_ON(!local->scan_req))
return false;
was_hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
if (was_hw_scan && !aborted && ieee80211_prep_hw_scan(local)) {
ieee80211_queue_delayed_work(&local->hw,
&local->scan_work, 0);
mutex_unlock(&local->mtx);
return;
return false;
}
kfree(local->hw_scan_req);
@ -289,23 +285,25 @@ static void __ieee80211_scan_completed(struct ieee80211_hw *hw, bool aborted)
local->scanning = 0;
local->scan_channel = NULL;
/* we only have to protect scan_req and hw/sw scan */
mutex_unlock(&local->mtx);
return true;
}
static void __ieee80211_scan_completed_finish(struct ieee80211_hw *hw,
bool was_hw_scan)
{
struct ieee80211_local *local = hw_to_local(hw);
ieee80211_hw_config(local, IEEE80211_CONF_CHANGE_CHANNEL);
if (was_hw_scan)
goto done;
if (!was_hw_scan) {
ieee80211_configure_filter(local);
drv_sw_scan_complete(local);
ieee80211_offchannel_return(local, true);
}
ieee80211_configure_filter(local);
drv_sw_scan_complete(local);
ieee80211_offchannel_return(local, true);
done:
mutex_lock(&local->mtx);
ieee80211_recalc_idle(local);
mutex_unlock(&local->mtx);
ieee80211_mlme_notify_scan_completed(local);
ieee80211_ibss_notify_scan_completed(local);
ieee80211_mesh_notify_scan_completed(local);
@ -366,6 +364,8 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
struct ieee80211_local *local = sdata->local;
int rc;
lockdep_assert_held(&local->mtx);
if (local->scan_req)
return -EBUSY;
@ -447,8 +447,8 @@ ieee80211_scan_get_channel_time(struct ieee80211_channel *chan)
return IEEE80211_PROBE_DELAY + IEEE80211_CHANNEL_TIME;
}
static int ieee80211_scan_state_decision(struct ieee80211_local *local,
unsigned long *next_delay)
static void ieee80211_scan_state_decision(struct ieee80211_local *local,
unsigned long *next_delay)
{
bool associated = false;
bool tx_empty = true;
@ -458,12 +458,6 @@ static int ieee80211_scan_state_decision(struct ieee80211_local *local,
struct ieee80211_sub_if_data *sdata;
struct ieee80211_channel *next_chan;
/* if no more bands/channels left, complete scan and advance to the idle state */
if (local->scan_channel_idx >= local->scan_req->n_channels) {
__ieee80211_scan_completed(&local->hw, false);
return 1;
}
/*
* check if at least one STA interface is associated,
* check if at least one STA interface has pending tx frames
@ -535,7 +529,6 @@ static int ieee80211_scan_state_decision(struct ieee80211_local *local,
}
*next_delay = 0;
return 0;
}
static void ieee80211_scan_state_leave_oper_channel(struct ieee80211_local *local,
@ -651,7 +644,7 @@ void ieee80211_scan_work(struct work_struct *work)
container_of(work, struct ieee80211_local, scan_work.work);
struct ieee80211_sub_if_data *sdata = local->scan_sdata;
unsigned long next_delay = 0;
bool aborted;
bool aborted, hw_scan, finish;
mutex_lock(&local->mtx);
@ -704,8 +697,12 @@ void ieee80211_scan_work(struct work_struct *work)
do {
switch (local->next_scan_state) {
case SCAN_DECISION:
if (ieee80211_scan_state_decision(local, &next_delay))
return;
/* if no more bands/channels left, complete scan */
if (local->scan_channel_idx >= local->scan_req->n_channels) {
aborted = false;
goto out_complete;
}
ieee80211_scan_state_decision(local, &next_delay);
break;
case SCAN_SET_CHANNEL:
ieee80211_scan_state_set_channel(local, &next_delay);
@ -726,8 +723,11 @@ void ieee80211_scan_work(struct work_struct *work)
return;
out_complete:
hw_scan = test_bit(SCAN_HW_SCANNING, &local->scanning);
finish = __ieee80211_scan_completed(&local->hw, aborted, hw_scan);
mutex_unlock(&local->mtx);
__ieee80211_scan_completed(&local->hw, aborted);
if (finish)
__ieee80211_scan_completed_finish(&local->hw, hw_scan);
return;
out:
@ -796,6 +796,7 @@ int ieee80211_request_internal_scan(struct ieee80211_sub_if_data *sdata,
void ieee80211_scan_cancel(struct ieee80211_local *local)
{
bool abortscan;
bool finish = false;
cancel_delayed_work_sync(&local->scan_work);
@ -806,8 +807,10 @@ void ieee80211_scan_cancel(struct ieee80211_local *local)
mutex_lock(&local->mtx);
abortscan = test_bit(SCAN_SW_SCANNING, &local->scanning) ||
(!local->scanning && local->scan_req);
if (abortscan)
finish = __ieee80211_scan_completed(&local->hw, true, false);
mutex_unlock(&local->mtx);
if (abortscan)
__ieee80211_scan_completed(&local->hw, true);
if (finish)
__ieee80211_scan_completed_finish(&local->hw, false);
}