RE: [PATCH v7 4/6] wifi: rtw88: sdio: track free TX pages and OQT credits for RTL8723BS

Luka Gejak <[email protected]> wrote:
> On August 25, 2026 9:25:13 AM GMT+02:00, Ping-Ke Shih <[email protected]> wrote:
> >Luka Gejak <[email protected]> wrote:
> >> Hi Ping-Ke,
> >>
> >> On August 25, 2026 8:12:58 AM GMT+02:00, Ping-Ke Shih <[email protected]> wrote:
> >> > guard(mutex)(&rtwsdio->tx_credit_lock);
> >>
> >> The lock is only taken for this chip, and guard() is unconditional, so I
> >> split the locked region into its own function instead of branching around
> >> the lock:
> >>
> >>         if (!rtw_is_8723bs(rtwdev)) {
> >>                 txsize = sdio_align_size(rtwsdio->sdio_func, skb->len);
> >>
> >>                 ret = rtw_sdio_check_free_txpg(rtwdev, queue, txsize);
> >>                 if (ret)
> >>                         return ret;
> >>
> >>                 return rtw_sdio_write_to_port(rtwdev, skb, queue, txaddr,
> >>                                               txsize);
> >>         }
> >>         ...
> >>         guard(mutex)(&rtwsdio->tx_credit_lock);
> >>
> >>         return rtw_sdio_8723bs_write_port(rtwdev, skb, queue, txaddr, txsize,
> >>                                           write_size);
> >
> >I meant
> >
> >    if (rtw_is_8723bs(rtwdev))
> >        guard(mutex)(&rtwsdio->tx_credit_lock);
> >
> >Doesn't it work?
> >
> >
> 
> I tried it, and no. guard() expands to a declaration, and a declaration
> cannot be the body of an if, so it does not build:
> 
>   sdio.c: In function 'rtw_sdio_write_port':
>   include/linux/cleanup.h:302:9: error: expected expression before
>   'class_mutex_t'
>     302 |         class_##_name##_t var __cleanup(...) =
> 
> Adding braces builds cleanly, which is the more dangerous version, because
> the cleanup then runs at the closing brace and the mutex is released again
> before any of the code it is meant to protect runs.
> 
> That is why I moved the locked part into its own function: the guard needs
> a scope that is exactly the critical section, and an if body is either too
> small or not allowed.

Okay. Got it.