linux-kernel - Re: [PATCH] block: uapi: Fix compliation warning of using IOPRIO_PRIO

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Message-ID: <CAHJ8P3KaWbKrGnmqmb_W9xw0k_F7i8oRK+MYscP02-k1XPyWfw@mail.gmail.com>
Date: Tue, 9 Jul 2024 11:27:03 +0800
From: Zhiguo Niu <niuzhiguo84@...il.com>
To: axboe@...nel.dk, dlemoal@...nel.org, Christoph Hellwig <hch@....de>
Cc: Bart Van Assche <bvanassche@....org>, linux-kernel@...r.kernel.org, 
	Zhiguo Niu <zhiguo.niu@...soc.com>, ke.wang@...soc.com
Subject: Re: [PATCH] block: uapi: Fix compliation warning of using IOPRIO_PRIO_DATA

kindly ping...

Bart Van Assche <bvanassche@....org> 于2024年6月1日周六 04:13写道：


>
> On 5/31/24 04:31, Zhiguo Niu wrote:
> > Generally, the input of IOPRIO_PRIO_DATA has 16 bits. If use format "%d"
> > to printk IOPRIO_PRIO_DATA, there will be the following warning or error.
> >
> > fs/f2fs/sysfs.c:348:31: warning: format ‘%d’ expects argument of type ‘int’, but argument 4 has type ‘long unsigned int’ [-Wformat=]
> >     return sysfs_emit(buf, "%s,%d\n",
> >                                ~^
> >                                %ld
> >
> > This is because the output of IOPRIO_PRIO_DATA is converted to "UL" from
> > IOPRIO_PRIO_MASK, which is not reasonable. unsigned int is more suitable.
> >
> > Signed-off-by: Zhiguo Niu <zhiguo.niu@...soc.com>
> > ---
> >   include/uapi/linux/ioprio.h | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h
> > index bee2bdb0..9ead07f 100644
> > --- a/include/uapi/linux/ioprio.h
> > +++ b/include/uapi/linux/ioprio.h
> > @@ -11,7 +11,7 @@
> >   #define IOPRIO_CLASS_SHIFT  13
> >   #define IOPRIO_NR_CLASSES   8
> >   #define IOPRIO_CLASS_MASK   (IOPRIO_NR_CLASSES - 1)
> > -#define IOPRIO_PRIO_MASK     ((1UL << IOPRIO_CLASS_SHIFT) - 1)
> > +#define IOPRIO_PRIO_MASK     ((1U << IOPRIO_CLASS_SHIFT) - 1)
> >
> >   #define IOPRIO_PRIO_CLASS(ioprio)   \
> >       (((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK)
>
> This change is safe even if the mask is applied to an expression with more bits
> than an int because of the integer promotion rules. Hence:
>
> Reviewed-by: Bart Van Assche <bvanassche@....org>