From: Andrew Morton <akpm@linux-foundation.org>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] proc: use typeof_member() macro
Date: Wed, 29 May 2019 15:33:37 -0700 [thread overview]
Message-ID: <20190529153337.3e8fcd2b6b54e11e5ef23d04@linux-foundation.org> (raw)
In-Reply-To: <20190529191110.GB5703@avx2>
On Wed, 29 May 2019 22:11:10 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:
> Don't repeat function signatures twice.
>
> This is a kind-of-precursor for "struct proc_ops".
>
> Note:
>
> typeof(pde->proc_fops->...) ...;
>
> can't be used because ->proc_fops is "const struct file_operations *".
> "const" prevents assignment down the code and it can't be deleted
> in the type system.
>
> ...
>
> --- a/fs/proc/inode.c
> +++ b/fs/proc/inode.c
> @@ -200,7 +200,8 @@ static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
> struct proc_dir_entry *pde = PDE(file_inode(file));
> loff_t rv = -EINVAL;
> if (use_pde(pde)) {
> - loff_t (*llseek)(struct file *, loff_t, int);
> + typeof_member(struct file_operations, llseek) llseek;
ooh. That's pretty nifty.
next prev parent reply other threads:[~2019-05-29 22:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-29 19:07 [PATCH 1/2] add typeof_member() macro Alexey Dobriyan
2019-05-29 19:11 ` [PATCH 2/2] proc: use " Alexey Dobriyan
2019-05-29 22:33 ` Andrew Morton [this message]
2019-05-30 11:37 ` [PATCH 1/2] add " David Laight
2019-05-30 11:53 ` Joe Perches
2019-05-30 19:57 ` Alexey Dobriyan
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