From mboxrd@z Thu Jan  1 00:00:00 1970
From: martin.brugnara@gmail.com (Martin Brugnara)
Date: Mon, 23 Dec 2013 11:23:07 +0100
Subject: Linux-wireless: why use macro to call functions
Message-ID: <52b80f05.c7b60e0a.2515.5c5e@mx.google.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

Hi,

Why here is used a macro instead of an inline func.

Thanks,
Martin

-----Original Message-----
From: "Daniel Baluta" <daniel.baluta@gmail.com>
Sent: ?23/?12/?2013 08.27
To: "Fred Chou" <fred.chou.nd@gmail.com>
Cc: "kernelnewbies" <kernelnewbies@kernelnewbies.org>
Subject: Re: Linux-wireless: why use macro to call functions

On Mon, Dec 23, 2013 at 8:05 AM, Fred Chou <fred.chou.nd@gmail.com> wrote:
> Hi,
>
> I was studying the Linux wireless subsystem code and noticed this code (in
> ieee80211_rx_handlers):
>
> It first defines the macro:
>
> #define CALL_RXH(rxh) \
>  do {                            \
>              res = rxh(rx);          \
>              if (res != RX_CONTINUE) \
>                      goto rxh_next;  \
>      } while (0);
>
> Then the macro is used to call a series of functions:
>
> CALL_RXH(ieee80211_rx_h_check_more_data)
> CALL_RXH(ieee80211_rx_h_uapsd_and_pspoll)
> CALL_RXH(ieee80211_rx_h_sta_process)
> CALL_RXH(ieee80211_rx_h_decrypt)
> CALL_RXH(ieee80211_rx_h_defragment)
> CALL_RXH(ieee80211_rx_h_michael_mic_verify)
>
>
> My question is, why not just call the functions directly like:
>
> ieee80211_rx_h_check_more_data(rx);
> ieee80211_rx_h_uapsd_and_pspoll(rx);
>
> ...
>
> Is it just for the sake of outlining the code for easy reading? Appreciate
> if anyone can explain. Thanks!

Hi,

As you can see above the macro does also error checking.I don't necessarily
think that the code is easier to read, but it can save you some typing.

thanks,
Daniel.

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