From: Christoph Hellwig <hch@infradead.org>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tejun Heo <tj@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Nathan Chancellor <natechancellor@gmail.com>,
Nick Desaulniers <ndesaulniers@google.com>,
Arnd Bergmann <arnd@arndb.de>,
Amir Goldstein <amir73il@gmail.com>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
clang-built-linux@googlegroups.com
Subject: Re: [PATCH] seq_file: fix clang warning for NULL pointer arithmetic
Date: Tue, 27 Oct 2020 10:44:50 +0000 [thread overview]
Message-ID: <20201027104450.GA8864@infradead.org> (raw)
In-Reply-To: <20201026215321.3894419-1-arnd@kernel.org>
> index f277d023ebcd..b55e6ef4d677 100644
> --- a/fs/kernfs/file.c
> +++ b/fs/kernfs/file.c
> @@ -124,7 +124,7 @@ static void *kernfs_seq_start(struct seq_file *sf, loff_t *ppos)
> * The same behavior and code as single_open(). Returns
> * !NULL if pos is at the beginning; otherwise, NULL.
> */
> - return NULL + !*ppos;
> + return (void *)(uintptr_t)!*ppos;
Yikes. This is just horrible, why bnot the completely obvious:
if (ops->seq_start) {
...
return next;
}
if (*ppos)
return NULL;
return ppos; /* random cookie */
> static void *single_start(struct seq_file *p, loff_t *pos)
> {
> - return NULL + (*pos == 0);
> + return (void *)(uintptr_t)(*pos == 0);
Same here.
next prev parent reply other threads:[~2020-10-27 10:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 21:52 [PATCH] seq_file: fix clang warning for NULL pointer arithmetic Arnd Bergmann
2020-10-27 1:49 ` Nathan Chancellor
2020-10-27 10:44 ` Christoph Hellwig [this message]
2020-10-27 14:51 ` Arnd Bergmann
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