linux-kernel - Re: [PATCH] staging: rtl8192u: Remove an unnecessary NULL check

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Message-ID: <20190522092412.GR31203@kadam>
Date:   Wed, 22 May 2019 12:24:12 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Nick Desaulniers <ndesaulniers@...gle.com>
Cc:     Nathan Chancellor <natechancellor@...il.com>,
        devel@...verdev.osuosl.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        John Whitmore <johnfwhitmore@...il.com>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Richard Smith <richardsmith@...gle.com>
Subject: Re: [PATCH] staging: rtl8192u: Remove an unnecessary NULL check

On Tue, May 21, 2019 at 03:57:46PM -0700, Nick Desaulniers wrote:
> > > -       if (param->u.wpa_ie.len > MAX_WPA_IE_LEN ||
> > > -           (param->u.wpa_ie.len && !param->u.wpa_ie.data))
> >
> > Right so, the types in this expression:
> >
> > param: struct ieee_param*
> > param->u: *anonymous union*
> > param->u.wpa_ie: *anonymous struct*
> > param->u.wpa_ie.len: u32
> > param->u.wpa_ie.data: u8 [0]
> > as defined in drivers/staging/rtl8192u/ieee80211/ieee80211.h#L295
> > https://github.com/ClangBuiltLinux/linux/blob/9c7db5004280767566e91a33445bf93aa479ef02/drivers/staging/rtl8192u/ieee80211/ieee80211.h#L295-L322
> >
> > so this is a tricky case, because in general array members can never
> > themselves be NULL,


Unless they array was the first struct member, obviously.


> >  and usually I trust -Wpointer-bool-conversion, but
> > this is a special case because of the flexible array member:

Nah.  It's the same thing.  That patch is fine.

regards,
dan carpenter