wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE for il_sta in il3945_rs_get_rate()

[PATCH v3] wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE for il_sta in il3945_rs_get_rate()

Posted by Tuo Li 4 weeks, 1 day ago

In this function, il_sta is not expected to be NULL. Add a defensive
WARN_ON_ONCE() to catch this unexpected condition and aid debugging.

Signed-off-by: Tuo Li <islituo@gmail.com>
---
v3:
* Replace plain NULL check with WARN_ON_ONCE() and update subject to better
  reflect defensive nature of the check.
  Thanks to Johannes Berg and Stanislaw Gruszka for helpful advice.
v2:
* Return early for uninitialized STA il data and align D_RATE messages with
  il3945_rs_tx_status(). Add a wifi: prefix to the patch title.
  Thanks to Stanislaw Gruszka for the helpful advice.
---
 drivers/net/wireless/intel/iwlegacy/3945-rs.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/wireless/intel/iwlegacy/3945-rs.c b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
index 1826c37c090c..463565ce14af 100644
--- a/drivers/net/wireless/intel/iwlegacy/3945-rs.c
+++ b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
@@ -626,6 +626,9 @@ il3945_rs_get_rate(void *il_r, struct ieee80211_sta *sta, void *il_sta,
 
 	D_RATE("enter\n");
 
+	if (WARN_ON_ONCE(!il_sta))
+		return;
+
 	/* Treat uninitialized rate scaling data same as non-existing. */
 	if (rs_sta && !rs_sta->il) {
 		D_RATE("Rate scaling information not initialized yet.\n");
-- 
2.43.0

Re: [PATCH v3] wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE for il_sta in il3945_rs_get_rate()

Posted by Stanislaw Gruszka 4 weeks, 1 day ago

Hi Tuo,

On Fri, Jan 09, 2026 at 11:40:14AM +0800, Tuo Li wrote:
> In this function, il_sta is not expected to be NULL. Add a defensive
> WARN_ON_ONCE() to catch this unexpected condition and aid debugging.
> 
> Signed-off-by: Tuo Li <islituo@gmail.com>
> ---
> v3:
> * Replace plain NULL check with WARN_ON_ONCE() and update subject to better
>   reflect defensive nature of the check.
>   Thanks to Johannes Berg and Stanislaw Gruszka for helpful advice.
> v2:
> * Return early for uninitialized STA il data and align D_RATE messages with
>   il3945_rs_tx_status(). Add a wifi: prefix to the patch title.
>   Thanks to Stanislaw Gruszka for the helpful advice.
> ---
>  drivers/net/wireless/intel/iwlegacy/3945-rs.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/wireless/intel/iwlegacy/3945-rs.c b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> index 1826c37c090c..463565ce14af 100644
> --- a/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> +++ b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> @@ -626,6 +626,9 @@ il3945_rs_get_rate(void *il_r, struct ieee80211_sta *sta, void *il_sta,
>  
>  	D_RATE("enter\n");
>  
> +	if (WARN_ON_ONCE(!il_sta))
> +		return;
> +

Sorry for giving you wrong advice before, but after examining related code
I agree with Johannes the il_sta can not be NULL.
Now, I think we should just remove il_sta/rs_sta pointer check.

Regards
Stanislaw

Re: [PATCH v3] wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE for il_sta in il3945_rs_get_rate()

Posted by Tuo Li 4 weeks, 1 day ago

Hi Stanislaw,

On Fri, Jan 9, 2026 at 5:02 PM Stanislaw Gruszka <stf_xl@wp.pl> wrote:
>
> Hi Tuo,
>
> On Fri, Jan 09, 2026 at 11:40:14AM +0800, Tuo Li wrote:
> > In this function, il_sta is not expected to be NULL. Add a defensive
> > WARN_ON_ONCE() to catch this unexpected condition and aid debugging.
> >
> > Signed-off-by: Tuo Li <islituo@gmail.com>
> > ---
> > v3:
> > * Replace plain NULL check with WARN_ON_ONCE() and update subject to better
> >   reflect defensive nature of the check.
> >   Thanks to Johannes Berg and Stanislaw Gruszka for helpful advice.
> > v2:
> > * Return early for uninitialized STA il data and align D_RATE messages with
> >   il3945_rs_tx_status(). Add a wifi: prefix to the patch title.
> >   Thanks to Stanislaw Gruszka for the helpful advice.
> > ---
> >  drivers/net/wireless/intel/iwlegacy/3945-rs.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/net/wireless/intel/iwlegacy/3945-rs.c b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> > index 1826c37c090c..463565ce14af 100644
> > --- a/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> > +++ b/drivers/net/wireless/intel/iwlegacy/3945-rs.c
> > @@ -626,6 +626,9 @@ il3945_rs_get_rate(void *il_r, struct ieee80211_sta *sta, void *il_sta,
> >
> >       D_RATE("enter\n");
> >
> > +     if (WARN_ON_ONCE(!il_sta))
> > +             return;
> > +
>
> Sorry for giving you wrong advice before, but after examining related code
> I agree with Johannes the il_sta can not be NULL.
> Now, I think we should just remove il_sta/rs_sta pointer check.
>
> Regards
> Stanislaw

Thanks for the follow-up and your patience. I appreciate you taking
another look at the code.

Just to confirm, would you like me to submit a v4 patch that removes the
unnecessary il_sta / rs_sta checks, e.g.:

in il3945_rs_get_rate():

- if (rs_sta && !rs_sta->il) {
+ if (!rs_sta->il) {

and in il3945_rs_tx_status():

- if (!il_sta) {
-     D_RATE("leave: No STA il data to update!\n");
-     return;
- }

If a v4 is not needed, I'm also fine with dropping this patch series.

Best regards,
Tuo

Re: [PATCH v3] wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE for il_sta in il3945_rs_get_rate()

Posted by Stanislaw Gruszka 4 weeks ago

Hi

On Fri, Jan 09, 2026 at 11:12:55PM +0800, Tuo Li wrote:
> > Sorry for giving you wrong advice before, but after examining related code
> > I agree with Johannes the il_sta can not be NULL.
> > Now, I think we should just remove il_sta/rs_sta pointer check.
> >
> > Regards
> > Stanislaw
> 
> Thanks for the follow-up and your patience. I appreciate you taking
> another look at the code.
> 
> Just to confirm, would you like me to submit a v4 patch that removes the
> unnecessary il_sta / rs_sta checks, e.g.:
> 
> in il3945_rs_get_rate():
> 
> - if (rs_sta && !rs_sta->il) {
> + if (!rs_sta->il) {
> 
> and in il3945_rs_tx_status():
> 
> - if (!il_sta) {
> -     D_RATE("leave: No STA il data to update!\n");
> -     return;
> - }

Yes, please post those changes as v4.

Thanks
Stanislaw

Re: [PATCH v3] wifi: iwlegacy: 3945-rs: add a defensive WARN_ON_ONCE for il_sta in il3945_rs_get_rate()

Posted by Tuo Li 4 weeks ago

Hi Stanislaw,

On Sat, Jan 10, 2026 at 4:42 AM Stanislaw Gruszka <stf_xl@wp.pl> wrote:
>
> Hi
>
> On Fri, Jan 09, 2026 at 11:12:55PM +0800, Tuo Li wrote:
> > > Sorry for giving you wrong advice before, but after examining related code
> > > I agree with Johannes the il_sta can not be NULL.
> > > Now, I think we should just remove il_sta/rs_sta pointer check.
> > >
> > > Regards
> > > Stanislaw
> >
> > Thanks for the follow-up and your patience. I appreciate you taking
> > another look at the code.
> >
> > Just to confirm, would you like me to submit a v4 patch that removes the
> > unnecessary il_sta / rs_sta checks, e.g.:
> >
> > in il3945_rs_get_rate():
> >
> > - if (rs_sta && !rs_sta->il) {
> > + if (!rs_sta->il) {
> >
> > and in il3945_rs_tx_status():
> >
> > - if (!il_sta) {
> > -     D_RATE("leave: No STA il data to update!\n");
> > -     return;
> > - }
>
> Yes, please post those changes as v4.
>
> Thanks
> Stanislaw

Thanks for your reply.

I will post these changes and submit a v4 patch shortly.

Best regards,
Tuo