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Thu, 14 May 2026 07:44:49 -0700 (PDT) Message-ID: <0673a432-6d70-47b0-bb54-42f6a207d2b2@kernel.dk> Date: Thu, 14 May 2026 08:44:47 -0600 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] io_uring: parenthesize io_ring_head_to_buf() expansion To: Caleb Sander Mateos Cc: Yi Xie , io-uring@vger.kernel.org References: <20260514083443.203387-1-xieyi@kylinos.cn> <49a10373-f2d8-4813-b9d6-25cd2a0f2fe6@kernel.dk> Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 5/14/26 8:43 AM, Caleb Sander Mateos wrote: > On Thu, May 14, 2026 at 7:25 AM Jens Axboe wrote: >> >> On 5/14/26 8:22 AM, Caleb Sander Mateos wrote: >>> On Thu, May 14, 2026 at 1:35?AM Yi Xie wrote: >>>> >>>> Wrap the io_ring_head_to_buf() macro value in an extra pair of parentheses >>>> so it is safe when composed into larger expressions, and to satisfy >>>> scripts/checkpatch.pl. >>>> >>>> Signed-off-by: Yi Xie >>>> --- >>>> io_uring/kbuf.c | 2 +- >>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>> >>>> diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c >>>> index 63061aa1cab9..dd54e43e9ddf 100644 >>>> --- a/io_uring/kbuf.c >>>> +++ b/io_uring/kbuf.c >>>> @@ -21,7 +21,7 @@ >>>> #define MAX_BIDS_PER_BGID (1 << 16) >>>> >>>> /* Mapped buffer ring, return io_uring_buf from head */ >>>> -#define io_ring_head_to_buf(br, head, mask) &(br)->bufs[(head) & (mask)] >>>> +#define io_ring_head_to_buf(br, head, mask) (&(br)->bufs[(head) & (mask)]) >>> >>> Is there a reason this can't just be an inline function? >> >> No reason at all. But also don't see a strong reason why it can't just >> be a define. And generally I don't like cleanups like this, but this one >> at least made sense to me. > > A macro can certainly work, but as this patch shows, it's tricky to > remember all the parentheses. An inline function also results in > better compiler error messages since the arguments are strongly typed. > And not applicable in this case, but if an argument is used multiple > times, a function ensures it's only evaluated once. I would generally > only reach for a macro when something can't be expressed as an inline > function. I do know the benefits of a function over a macro :-) I just don't think it'll buy us anything in this case. -- Jens Axboe