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From: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	linux-nfc@lists.01.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 7/8] nfc: hci: pass callback data param as pointer in nci_request()
Date: Fri, 30 Jul 2021 15:56:19 +0200	[thread overview]
Message-ID: <53f89bae-fcb5-8e7c-0b03-effa156584fe@canonical.com> (raw)
In-Reply-To: <20210730064922.078bd222@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>

On 30/07/2021 15:49, Jakub Kicinski wrote:
> 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@canonical.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

Indeed. Not that code before was better - the logic was exactly the
same. I might think more how to avoid these and maybe pass pointer to
stack value (like in other cases).

The 7/8 and 8/8 could be skipped in such case.

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

Yes, it will resolve all warnings. No further action needed, at least I
am not aware of any new issues.

Best regards,
Krzysztof

  reply	other threads:[~2021-07-30 13:56 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30  6:56 [PATCH v2 0/8] nfc: constify pointed data - missed part Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 1/8] nfc: mrvl: correct nfcmrvl_spi_parse_dt() device_node argument Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 2/8] nfc: annotate af_nfc_exit() as __exit Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 3/8] nfc: hci: annotate nfc_llc_init() as __init Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 4/8] nfc: constify several pointers to u8, char and sk_buff Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 5/8] nfc: constify local pointer variables Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 6/8] nfc: nci: constify several pointers to u8, sk_buff and other structs Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 7/8] nfc: hci: pass callback data param as pointer in nci_request() Krzysztof Kozlowski
2021-07-30 13:49   ` Jakub Kicinski
2021-07-30 13:56     ` Krzysztof Kozlowski [this message]
2021-07-30 13:58       ` Jakub Kicinski
2021-07-30 14:03         ` Krzysztof Kozlowski
2021-07-30  6:56 ` [PATCH v2 8/8] nfc: hci: cleanup unneeded spaces Krzysztof Kozlowski

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