scan_work is never stopped if the device was unplugged during
s/w scan.
Signed-off-by: Rajkumar Manoharan <[email protected]>
---
net/mac80211/main.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 30e6a68..d2aa0be 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -964,6 +964,8 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
unregister_inetaddr_notifier(&local->ifa_notifier);
#endif
+ cancel_delayed_work_sync(&local->scan_work);
+
rtnl_lock();
/*
--
1.7.5.1
On Fri, 2011-05-13 at 11:05 +0530, Rajkumar Manoharan wrote:
> > How did you come to that conclusion? ieee80211_do_stop() does stop the
> > scan.
> >
> True. But Sometimes ieee80211_scan_cancel is waiting for mutex where
> the lock was already aquired by scan work and scan_work never releases
> the lock till scan completion whenever next_delay == 0.
But that shouldn't take a long time. And if it's "stuck" there, then
cancel_delayed_work_sync() will also wait for it.
> This scenario was observed while unplug the card during scan.
If this happens then mac80211 will still make calls to the driver, I
don't think we can avoid this and drivers will need to handle it. Maybe
the driver is repeatedly timing out somewhere?
johannes
On Thu, 2011-05-12 at 22:39 +0530, Rajkumar Manoharan wrote:
> scan_work is never stopped if the device was unplugged during
> s/w scan.
How did you come to that conclusion? ieee80211_do_stop() does stop the
scan.
johannes
On Thu, May 12, 2011 at 10:55:21PM +0530, Johannes Berg wrote:
> On Thu, 2011-05-12 at 22:39 +0530, Rajkumar Manoharan wrote:
> > scan_work is never stopped if the device was unplugged during
> > s/w scan.
>
> How did you come to that conclusion? ieee80211_do_stop() does stop the
> scan.
>
True. But Sometimes ieee80211_scan_cancel is waiting for mutex where
the lock was already aquired by scan work and scan_work never releases
the lock till scan completion whenever next_delay == 0.
This scenario was observed while unplug the card during scan.
--
Rajkumar
On Fri, May 13, 2011 at 09:13:36PM +0530, Johannes Berg wrote:
> On Fri, 2011-05-13 at 11:05 +0530, Rajkumar Manoharan wrote:
>
> > > How did you come to that conclusion? ieee80211_do_stop() does stop the
> > > scan.
> > >
> > True. But Sometimes ieee80211_scan_cancel is waiting for mutex where
> > the lock was already aquired by scan work and scan_work never releases
> > the lock till scan completion whenever next_delay == 0.
>
> But that shouldn't take a long time. And if it's "stuck" there, then
> cancel_delayed_work_sync() will also wait for it.
>
Agree. cancel_delayed_work_sync does not help to abort scan when
scan_work is in next_scan_state loop.
> > This scenario was observed while unplug the card during scan.
>
> If this happens then mac80211 will still make calls to the driver, I
> don't think we can avoid this and drivers will need to handle it. Maybe
> the driver is repeatedly timing out somewhere?
>
These unneccesary driver calls has to be avoided. How about the following
change to abort scan during scan loop.
diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index 4054399..9d18c43 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -384,11 +384,11 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
int i;
enum nl80211_channel_type orig_ct;
+ clear_bit(SDATA_STATE_RUNNING, &sdata->state);
+
if (local->scan_sdata == sdata)
ieee80211_scan_cancel(local);
- clear_bit(SDATA_STATE_RUNNING, &sdata->state);
-
/*
* Stop TX on this interface first.
*/
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index ea44a8e..6353f93 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -719,6 +719,11 @@ void ieee80211_scan_work(struct work_struct *work)
* without scheduling a new work
*/
do {
+ if (!test_bit(SDATA_STATE_RUNNING, &sdata->state)) {
+ aborted = true;
+ goto out_complete;
+ }
+
switch (local->next_scan_state) {
case SCAN_DECISION:
/* if no more bands/channels left, complete scan */
--
Rajkumar
On Fri, May 13, 2011 at 11:05:34AM +0530, Rajkumar Manoharan wrote:
> On Thu, May 12, 2011 at 10:55:21PM +0530, Johannes Berg wrote:
> > On Thu, 2011-05-12 at 22:39 +0530, Rajkumar Manoharan wrote:
> > > scan_work is never stopped if the device was unplugged during
> > > s/w scan.
> >
> > How did you come to that conclusion? ieee80211_do_stop() does stop the
> > scan.
> >
> True. But Sometimes ieee80211_scan_cancel is waiting for mutex where
> the lock was already aquired by scan work and scan_work never releases
> the lock till scan completion whenever next_delay == 0.
> This scenario was observed while unplug the card during scan.
So that looks like a bug somwhere in ieee80211_scan_state_* functions,
which should be fixed there, no?
Stanislaw
On Fri, 2011-05-13 at 22:48 +0530, Rajkumar Manoharan wrote:
> These unneccesary driver calls has to be avoided. How about the following
> change to abort scan during scan loop.
>
> diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
> index 4054399..9d18c43 100644
> --- a/net/mac80211/iface.c
> +++ b/net/mac80211/iface.c
> @@ -384,11 +384,11 @@ static void ieee80211_do_stop(struct ieee80211_sub_if_data *sdata,
> int i;
> enum nl80211_channel_type orig_ct;
>
> + clear_bit(SDATA_STATE_RUNNING, &sdata->state);
> +
> if (local->scan_sdata == sdata)
> ieee80211_scan_cancel(local);
>
> - clear_bit(SDATA_STATE_RUNNING, &sdata->state);
> -
> /*
> * Stop TX on this interface first.
> */
> diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
> index ea44a8e..6353f93 100644
> --- a/net/mac80211/scan.c
> +++ b/net/mac80211/scan.c
> @@ -719,6 +719,11 @@ void ieee80211_scan_work(struct work_struct *work)
> * without scheduling a new work
> */
> do {
> + if (!test_bit(SDATA_STATE_RUNNING, &sdata->state)) {
> + aborted = true;
> + goto out_complete;
> + }
> +
Seems reasonable, but you should use ieee80211_sdata_running().
johannes