| Message ID | YBfy+zc3XkiyIe6t@mwanda (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | ath11k: fix a locking bug in ath11k_mac_op_start() | expand |
On 2/1/21 4:24 AM, Dan Carpenter wrote: > This error path leads to a Smatch warning: > > drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start() > error: double unlocked '&ar->conf_mutex' (orig line 4251) > > We're not holding the lock when we do the "goto err;" so it leads to a > double unlock. We should hold the lock because the error path sets > "ar->state" so the right fix is to take the lock before doing the goto. > > Fixes: c83c500b55b6 ("ath11k: enable idle power save mode") > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> > --- > drivers/net/wireless/ath/ath11k/mac.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c > index c1608f64ea95..12e981e9e3d7 100644 > --- a/drivers/net/wireless/ath/ath11k/mac.c > +++ b/drivers/net/wireless/ath/ath11k/mac.c > @@ -4259,6 +4259,7 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw) > 1, pdev->pdev_id); > if (ret) { > ath11k_err(ab, "failed to enable idle ps: %d\n", ret); > + mutex_lock(&ar->conf_mutex); > goto err; > } > } It seems moving idle_ps condition in between ath11k_wmi_pdev_lro_cfg() and mutex_unlock() is a better way in this case. Thanks, Peter
Peter Oh <peter.oh@eero.com> writes: > On 2/1/21 4:24 AM, Dan Carpenter wrote: >> This error path leads to a Smatch warning: >> >> drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start() >> error: double unlocked '&ar->conf_mutex' (orig line 4251) >> >> We're not holding the lock when we do the "goto err;" so it leads to a >> double unlock. We should hold the lock because the error path sets >> "ar->state" so the right fix is to take the lock before doing the goto. >> >> Fixes: c83c500b55b6 ("ath11k: enable idle power save mode") >> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> >> --- >> drivers/net/wireless/ath/ath11k/mac.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c >> index c1608f64ea95..12e981e9e3d7 100644 >> --- a/drivers/net/wireless/ath/ath11k/mac.c >> +++ b/drivers/net/wireless/ath/ath11k/mac.c >> @@ -4259,6 +4259,7 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw) >> 1, pdev->pdev_id); >> if (ret) { >> ath11k_err(ab, "failed to enable idle ps: %d\n", ret); >> + mutex_lock(&ar->conf_mutex); >> goto err; >> } >> } > > It seems moving idle_ps condition in between ath11k_wmi_pdev_lro_cfg() > and mutex_unlock() > is a better way in this case. I agree. In Dan's approach I'm worried about the race when we unlock and lock again, the state can change in that case.
diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c index c1608f64ea95..12e981e9e3d7 100644 --- a/drivers/net/wireless/ath/ath11k/mac.c +++ b/drivers/net/wireless/ath/ath11k/mac.c @@ -4259,6 +4259,7 @@ static int ath11k_mac_op_start(struct ieee80211_hw *hw) 1, pdev->pdev_id); if (ret) { ath11k_err(ab, "failed to enable idle ps: %d\n", ret); + mutex_lock(&ar->conf_mutex); goto err; } }
This error path leads to a Smatch warning: drivers/net/wireless/ath/ath11k/mac.c:4269 ath11k_mac_op_start() error: double unlocked '&ar->conf_mutex' (orig line 4251) We're not holding the lock when we do the "goto err;" so it leads to a double unlock. We should hold the lock because the error path sets "ar->state" so the right fix is to take the lock before doing the goto. Fixes: c83c500b55b6 ("ath11k: enable idle power save mode") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> --- drivers/net/wireless/ath/ath11k/mac.c | 1 + 1 file changed, 1 insertion(+)