netdev - Re: [PATCH next 10/11] block: Use a boolean expression instead of max() on booleans

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Message-ID: <87sf2gjyn9.fsf@intel.com>
Date: Mon, 29 Jan 2024 11:07:38 +0200
From: Jani Nikula <jani.nikula@...ux.intel.com>
To: David Laight <David.Laight@...LAB.COM>, "'linux-kernel@...r.kernel.org'"
 <linux-kernel@...r.kernel.org>, 'Linus
 Torvalds' <torvalds@...ux-foundation.org>, 'Netdev'
 <netdev@...r.kernel.org>, "'dri-devel@...ts.freedesktop.org'"
 <dri-devel@...ts.freedesktop.org>
Cc: 'Jens Axboe' <axboe@...nel.dk>, "'Matthew Wilcox (Oracle)'"
 <willy@...radead.org>, 'Christoph Hellwig' <hch@...radead.org>,
 "'linux-btrfs@...r.kernel.org'" <linux-btrfs@...r.kernel.org>, 'Andrew
 Morton' <akpm@...ux-foundation.org>, 'Andy Shevchenko'
 <andriy.shevchenko@...ux.intel.com>, "'David S . Miller'"
 <davem@...emloft.net>, 'Dan
 Carpenter' <dan.carpenter@...aro.org>
Subject: Re: [PATCH next 10/11] block: Use a boolean expression instead of
 max() on booleans

On Sun, 28 Jan 2024, David Laight <David.Laight@...LAB.COM> wrote:
> blk_stack_limits() contains:
> 	t->zoned = max(t->zoned, b->zoned);
> These are bool, so it is just a bitwise or.

Should be a logical or, really. And || in code.

BR,
Jani.

> However it generates:
> error: comparison of constant â€˜0â€™ with boolean expression is always true [-Werror=bool-compare]
> inside the signedness check that max() does unless a '+ 0' is added.
> It is a shame the compiler generates this warning for code that will
> be optimised away.
>
> Change so that the extra '+ 0' can be removed.
>
> Signed-off-by: David Laight <david.laight@...lab.com>
> ---
>  block/blk-settings.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index 06ea91e51b8b..9ca21fea039d 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -688,7 +688,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
>  						   b->max_secure_erase_sectors);
>  	t->zone_write_granularity = max(t->zone_write_granularity,
>  					b->zone_write_granularity);
> -	t->zoned = max(t->zoned, b->zoned);
> +	t->zoned = t->zoned | b->zoned;
>  	return ret;
>  }
>  EXPORT_SYMBOL(blk_stack_limits);

-- 
Jani Nikula, Intel