netdev - Re: [PATCH v2 7/8] nfc: hci: pass callback data param as pointer in nci

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Date:   Fri, 30 Jul 2021 06:49:22 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
Cc:     "David S. Miller" <davem@...emloft.net>, linux-nfc@...ts.01.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 7/8] nfc: hci: pass callback data param as pointer in
 nci_request()

On Fri, 30 Jul 2021 08:56:24 +0200 Krzysztof Kozlowski wrote:
> The nci_request() receives a callback function and unsigned long data
> argument "opt" which is passed to the callback.  Almost all of the
> nci_request() callers pass pointer to a stack variable as data argument.
> Only few pass scalar value (e.g. u8).
> 
> All such callbacks do not modify passed data argument and in previous
> commit they were made as const.  However passing pointers via unsigned
> long removes the const annotation.  The callback could simply cast
> unsigned long to a pointer to writeable memory.
> 
> Use "const void *" as type of this "opt" argument to solve this and
> prevent modifying the pointed contents.  This is also consistent with
> generic pattern of passing data arguments - via "void *".  In few places
> passing scalar values, use casts via "unsigned long" to suppress any
> warnings.
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>

This generates a bunch of warnings:

net/nfc/nci/core.c:381:51: warning: Using plain integer as NULL pointer
net/nfc/nci/core.c:388:50: warning: Using plain integer as NULL pointer
net/nfc/nci/core.c:494:57: warning: Using plain integer as NULL pointer
net/nfc/nci/core.c:520:65: warning: Using plain integer as NULL pointer
net/nfc/nci/core.c:570:44: warning: Using plain integer as NULL pointer
net/nfc/nci/core.c:815:34: warning: Using plain integer as NULL pointer
net/nfc/nci/core.c:856:50: warning: Using plain integer as NULL pointer

BTW applying this set will resolve the warnings introduced by applying
"part 2" out of order, right? No further action needed?