Re: [PATCH] staging: rtl8723au: Remove dead code

[Supriya Karanth <iskaranth@gmail.com>]

On Thu, Mar 12, 2015 at 11:53:08AM -0500, Larry Finger wrote:
> On 03/12/2015 06:10 AM, Supriya Karanth wrote:
> >This dead code was detected by coccinelle while using --debug
> >option
> >diff --git a/drivers/staging/rtl8723au/core/rtw_mlme_ext.c b/drivers/staging/rtl8723au/core/rtw_mlme_ext.c
> >index 0e0f73c..db4f235 100644
> >--- a/drivers/staging/rtl8723au/core/rtw_mlme_ext.c
> >+++ b/drivers/staging/rtl8723au/core/rtw_mlme_ext.c
> >@@ -1619,7 +1619,6 @@ OnAssocReq23a(struct rtw_adapter *padapter, struct recv_frame *precv_frame)
> >  			} else {
> >  				break;
> >  			}
> >-			p = p + p[1] + 2;
> >  		}
> >  	}
> >
> 
> Like most of this driver, the code is ugly, but I think this is a coccinelle
> bug, not dead code.

I checked it myself and thought coccinelle was right
> 
> The statement that you are removing is at the end of a for loop. On the next
> pass through the loop, and there will be a next pass, the first statement is
> "left = end - p;"; therefore, the incrementation of p is not useless code.
> 

I was under the impression that the line "p = p + p[1] + 2;" will never
execute.

The for loop is in this form:
for (;;) {
	if (p) {
		if (...) {
		...

		}
		break;
	} else {
		break;
	}
	p = p ....
}

There is a "break" in both the if and else condition which will break out
of the for loop. I think the line "p = p + p[1] + 2;" is important but,
I think it never gets executed. Perhaps I am wrong and I am missing something.

> Have you tested your change? I would guess not. I think it would lead to an
> infinite loop.
I am sorry but no I haven't tested it as I do not have the Hardware. I have
tested the code format though and the line doesn't get executed.
> 
> The recent spate of untested patches generated by uncritical usage of
> various tools is quite tiresome!!

I understand. I am very sorry to have wasted your time.
> 
> NACK
> 
> Larry
> 
>