Commit 3827e33d authored by Jérôme Pouiller's avatar Jérôme Pouiller Committed by Greg Kroah-Hartman
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staging: wfx: workaround bug with "iw scan" 



mac80211 specification does not forbid hw_scan() to call
ieee80211_scan_completed(). However, from userspace point of view, not
all applications support this behavior. In particular, the code of iw
contains a big fat warning:

   /*
    * This code has a bug, which requires creating a separate
    * nl80211 socket to fix:
    * It is possible for a NL80211_CMD_NEW_SCAN_RESULTS or
    * NL80211_CMD_SCAN_ABORTED message to be sent by the kernel
    * before (!) we listen to it, because we only start listening
    * after we send our scan request.
    [...]
    * Alas, the kernel doesn't do that (yet).
    */

So, we have to avoid to call ieee80211_scan_completed() from hw_scan()
(it's a kind of unwritten rule).

This patch relocates the hw_scan() process to a work_struct to fix the
problem.

Signed-off-by: default avatarJérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20191217161318.31402-52-Jerome.Pouiller@silabs.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d1c015b4

drivers/staging/wfx/scan.c

+30 −17
Original line number Diff line number Diff line
@@ -71,23 +71,19 @@ static int send_scan_req(struct wfx_vif *wvif, 
	return i - start_idx;

}



int wfx_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,

		struct ieee80211_scan_request *hw_req)

/*

 * It is not really necessary to run scan request asynchronously. However,

 * there is a bug in "iw scan" when ieee80211_scan_completed() is called before

 * wfx_hw_scan() return

 */

void wfx_hw_scan_work(struct work_struct *work)

{

	struct wfx_dev *wdev = hw->priv;

	struct wfx_vif *wvif = (struct wfx_vif *) vif->drv_priv;

	struct wfx_vif *wvif = container_of(work, struct wfx_vif, scan_work);

	struct ieee80211_scan_request *hw_req = wvif->scan_req;

	int chan_cur, ret;



	WARN_ON(hw_req->req.n_channels > HIF_API_MAX_NB_CHANNELS);



	if (vif->type == NL80211_IFTYPE_AP)

		return -EOPNOTSUPP;



	if (wvif->state == WFX_STATE_PRE_STA)

		return -EBUSY;



	mutex_lock(&wvif->scan_lock);

	mutex_lock(&wdev->conf_mutex);

	mutex_lock(&wvif->wdev->conf_mutex);

	update_probe_tmpl(wvif, &hw_req->req);

	wfx_fwd_probe_req(wvif, true);

	chan_cur = 0;
@@ -96,18 +92,35 @@ int wfx_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif, 
		if (ret > 0)

			chan_cur += ret;

	} while (ret > 0 && chan_cur < hw_req->req.n_channels);

	__ieee80211_scan_completed_compat(hw, ret < 0);

	mutex_unlock(&wdev->conf_mutex);

	mutex_unlock(&wvif->wdev->conf_mutex);

	mutex_unlock(&wvif->scan_lock);

	__ieee80211_scan_completed_compat(wvif->wdev->hw, ret < 0);

	if (wvif->delayed_unjoin) {

		wvif->delayed_unjoin = false;

		wfx_tx_lock(wdev);

		wfx_tx_lock(wvif->wdev);

		if (!schedule_work(&wvif->unjoin_work))

			wfx_tx_unlock(wdev);

			wfx_tx_unlock(wvif->wdev);

	} else if (wvif->delayed_link_loss) {

		wvif->delayed_link_loss = false;

		wfx_cqm_bssloss_sm(wvif, 1, 0, 0);

	}

}



int wfx_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,

		struct ieee80211_scan_request *hw_req)

{

	struct wfx_vif *wvif = (struct wfx_vif *)vif->drv_priv;



	WARN_ON(hw_req->req.n_channels > HIF_API_MAX_NB_CHANNELS);



	if (vif->type == NL80211_IFTYPE_AP)

		return -EOPNOTSUPP;



	if (wvif->state == WFX_STATE_PRE_STA)

		return -EBUSY;



	wvif->scan_req = hw_req;

	schedule_work(&wvif->scan_work);

	return 0;

}

drivers/staging/wfx/scan.h

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
struct wfx_dev;

struct wfx_vif;



void wfx_hw_scan_work(struct work_struct *work);

int wfx_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,

		struct ieee80211_scan_request *req);

void wfx_scan_complete(struct wfx_vif *wvif,

drivers/staging/wfx/sta.c

+1 −0
Original line number Diff line number Diff line
@@ -1427,6 +1427,7 @@ int wfx_add_interface(struct ieee80211_hw *hw, struct ieee80211_vif *vif) 


	mutex_init(&wvif->scan_lock);

	init_completion(&wvif->scan_complete);

	INIT_WORK(&wvif->scan_work, wfx_hw_scan_work);



	mutex_unlock(&wdev->conf_mutex);

drivers/staging/wfx/wfx.h

+2 −0
Original line number Diff line number Diff line
@@ -127,7 +127,9 @@ struct wfx_vif { 


	/* avoid some operations in parallel with scan */

	struct mutex		scan_lock;

	struct work_struct	scan_work;

	struct completion	scan_complete;

	struct ieee80211_scan_request *scan_req;



	struct completion	set_pm_mode_complete;

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