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staging: wfx: workaround bug with "iw scan"

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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: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20191217161318.31402-52-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jérôme Pouiller 2019-12-17 16:15:37 +00:00 committed by Greg Kroah-Hartman
parent d1c015b4ef
commit 3827e33d37
4 changed files with 42 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
drivers/staging/wfx/scan.c
View File

@ -71,12 +71,45 @@ static int send_scan_req(struct wfx_vif *wvif,
return i - start_idx;
}
/*
* 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_vif *wvif = container_of(work, struct wfx_vif, scan_work);
struct ieee80211_scan_request *hw_req = wvif->scan_req;
int chan_cur, ret;
mutex_lock(&wvif->scan_lock);
mutex_lock(&wvif->wdev->conf_mutex);
update_probe_tmpl(wvif, &hw_req->req);
wfx_fwd_probe_req(wvif, true);
chan_cur = 0;
do {
ret = send_scan_req(wvif, &hw_req->req, chan_cur);
if (ret > 0)
chan_cur += ret;
} while (ret > 0 && chan_cur < hw_req->req.n_channels);
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(wvif->wdev);
if (!schedule_work(&wvif->unjoin_work))
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_dev *wdev = hw->priv;
struct wfx_vif *wvif = (struct wfx_vif *) vif->drv_priv;
int chan_cur, ret;
struct wfx_vif *wvif = (struct wfx_vif *)vif->drv_priv;
WARN_ON(hw_req->req.n_channels > HIF_API_MAX_NB_CHANNELS);
@ -86,28 +119,8 @@ int wfx_hw_scan(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
if (wvif->state == WFX_STATE_PRE_STA)
return -EBUSY;
mutex_lock(&wvif->scan_lock);
mutex_lock(&wdev->conf_mutex);
update_probe_tmpl(wvif, &hw_req->req);
wfx_fwd_probe_req(wvif, true);
chan_cur = 0;
do {
ret = send_scan_req(wvif, &hw_req->req, chan_cur);
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->scan_lock);
if (wvif->delayed_unjoin) {
wvif->delayed_unjoin = false;
wfx_tx_lock(wdev);
if (!schedule_work(&wvif->unjoin_work))
wfx_tx_unlock(wdev);
} else if (wvif->delayed_link_loss) {
wvif->delayed_link_loss = false;
wfx_cqm_bssloss_sm(wvif, 1, 0, 0);
}
wvif->scan_req = hw_req;
schedule_work(&wvif->scan_work);
return 0;
}

1
drivers/staging/wfx/scan.h
View File

@ -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,

1
drivers/staging/wfx/sta.c
View File

@ -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);

2
drivers/staging/wfx/wfx.h
View File

@ -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;