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From: Masahiro Yamada <masahiroy@kernel.org>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Julia Lawall <julia.lawall@lip6.fr>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	linux-clk <linux-clk@vger.kernel.org>,
	linux-crypto@vger.kernel.org,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	linux-i2c@vger.kernel.org,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	Networking <netdev@vger.kernel.org>,
	ALSA Development Mailing List <alsa-devel@alsa-project.org>,
	DTML <devicetree@vger.kernel.org>
Subject: Re: [PATCH] treewide: remove redundent IS_ERR() before error code check
Date: Tue, 7 Jan 2020 15:28:33 +0900
Message-ID: <CAK7LNATbLESJ6CdPSN8bdpt7+4iOKW2L3c4OZaz2sLzqJH6BTw@mail.gmail.com> (raw)
In-Reply-To: <20200107051521.GF705@sol.localdomain>

On Tue, Jan 7, 2020 at 2:15 PM Eric Biggers <ebiggers@kernel.org> wrote:
>
> On Mon, Jan 06, 2020 at 01:58:33PM +0900, Masahiro Yamada wrote:
> > 'PTR_ERR(p) == -E*' is a stronger condition than IS_ERR(p).
> > Hence, IS_ERR(p) is unneeded.
> >
> > The semantic patch that generates this commit is as follows:
> >
> > // <smpl>
> > @@
> > expression ptr;
> > constant error_code;
> > @@
> > -IS_ERR(ptr) && (PTR_ERR(ptr) == - error_code)
> > +PTR_ERR(ptr) == - error_code
> > // </smpl>
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
>
> Any reason for not doing instead:
>
>         ptr == ERR_PTR(-error_code)
>
> ?

Because there is no reason to change

        PTR_ERR(ptr) == -error_code
to
        ptr == ERR_PTR(-error_code)



     if (PTR_ERR(ptr) == -error_code)
style seems to be used more often.

But, I think it is just a matter of preference after all.
Both work equally fine.



>  To me it seems weird to use PTR_ERR() on non-error pointers.  I even had to
> double check that it returns a 'long' and not an 'int'.  (If it returned an
> 'int', it wouldn't work...)
>
> - Eric



-- 
Best Regards
Masahiro Yamada

  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-06  4:58 Masahiro Yamada
2020-01-06  6:02 ` Stephen Boyd
2020-01-06  9:38 ` Bartosz Golaszewski
2020-01-06 10:05 ` Wolfram Sang
2020-01-07  5:15 ` Eric Biggers
2020-01-07  6:28   ` Masahiro Yamada [this message]
2020-01-07  9:52 ` Rafael J. Wysocki
2020-01-08 20:17 ` Rob Herring

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