From: Duoming Zhou duoming@zju.edu.cn
[ Upstream commit cc7ad0d77b51c872d629bcd98aea463a3c4109e7 ]
There is a deadlock in rtw_surveydone_event_callback(), which is shown below:
(Thread 1) | (Thread 2) | _set_timer() rtw_surveydone_event_callback()| mod_timer() spin_lock_bh() //(1) | (wait a time) ... | rtw_scan_timeout_handler() del_timer_sync() | spin_lock_bh() //(2) (wait timer to stop) | ...
We hold pmlmepriv->lock in position (1) of thread 1 and use del_timer_sync() to wait timer to stop, but timer handler also need pmlmepriv->lock in position (2) of thread 2. As a result, rtw_surveydone_event_callback() will block forever.
This patch extracts del_timer_sync() from the protection of spin_lock_bh(), which could let timer handler to obtain the needed lock. What`s more, we change spin_lock_bh() in rtw_scan_timeout_handler() to spin_lock_irq(). Otherwise, spin_lock_bh() will also cause deadlock() in timer handler.
Signed-off-by: Duoming Zhou duoming@zju.edu.cn Link: https://lore.kernel.org/r/20220409061836.60529-1-duoming@zju.edu.cn Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/staging/rtl8723bs/core/rtw_mlme.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c index cf79bec916c5..2c20bf26b10e 100644 --- a/drivers/staging/rtl8723bs/core/rtw_mlme.c +++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c @@ -749,7 +749,9 @@ void rtw_surveydone_event_callback(struct adapter *adapter, u8 *pbuf) }
if (check_fwstate(pmlmepriv, _FW_UNDER_SURVEY)) { + spin_unlock_bh(&pmlmepriv->lock); del_timer_sync(&pmlmepriv->scan_to_timer); + spin_lock_bh(&pmlmepriv->lock); _clr_fwstate_(pmlmepriv, _FW_UNDER_SURVEY); }
@@ -1584,11 +1586,11 @@ void rtw_scan_timeout_handler(struct timer_list *t) mlmepriv.scan_to_timer); struct mlme_priv *pmlmepriv = &adapter->mlmepriv;
- spin_lock_bh(&pmlmepriv->lock); + spin_lock_irq(&pmlmepriv->lock);
_clr_fwstate_(pmlmepriv, _FW_UNDER_SURVEY);
- spin_unlock_bh(&pmlmepriv->lock); + spin_unlock_irq(&pmlmepriv->lock);
rtw_indicate_scan_done(adapter, true); }