From: Andrew Morton <akpm@linux-foundation.org>
To: Xiu Jianfeng <xiujianfeng@huawei.com>
Cc: <keescook@chromium.org>, <laniel_francis@privacyrequired.com>,
<andriy.shevchenko@linux.intel.com>, <adobriyan@gmail.com>,
<linux@roeck-us.net>, <andreyknvl@gmail.com>, <dja@axtens.net>,
<ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
<kafai@fb.com>, <songliubraving@fb.com>, <yhs@fb.com>,
<john.fastabend@gmail.com>, <kpsingh@kernel.org>,
<linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
<bpf@vger.kernel.org>
Subject: Re: [PATCH -next 1/2] string.h: Introduce memset_range() for wiping members
Date: Tue, 7 Dec 2021 20:28:29 -0800 [thread overview]
Message-ID: <20211207202829.48d15f0ffa006e3656811784@linux-foundation.org> (raw)
In-Reply-To: <20211208030451.219751-2-xiujianfeng@huawei.com>
On Wed, 8 Dec 2021 11:04:50 +0800 Xiu Jianfeng <xiujianfeng@huawei.com> wrote:
> Motivated by memset_after() and memset_startat(), introduce a new helper,
> memset_range() that takes the target struct instance, the byte to write,
> and two member names where zeroing should start and end.
Is this likely to have more than a single call site?
> ...
>
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -291,6 +291,26 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count,
> sizeof(*(obj)) - offsetof(typeof(*(obj)), member)); \
> })
>
> +/**
> + * memset_range - Set a value ranging from member1 to member2, boundary included.
I'm not sure what "boundary included" means.
> + *
> + * @obj: Address of target struct instance
> + * @v: Byte value to repeatedly write
> + * @member1: struct member to start writing at
> + * @member2: struct member where writing should stop
Perhaps "struct member before which writing should stop"?
> + *
> + */
> +#define memset_range(obj, v, member_1, member_2) \
> +({ \
> + u8 *__ptr = (u8 *)(obj); \
> + typeof(v) __val = (v); \
> + BUILD_BUG_ON(offsetof(typeof(*(obj)), member_1) > \
> + offsetof(typeof(*(obj)), member_2)); \
> + memset(__ptr + offsetof(typeof(*(obj)), member_1), __val, \
> + offsetofend(typeof(*(obj)), member_2) - \
> + offsetof(typeof(*(obj)), member_1)); \
> +})
struct a {
int b;
int c;
int d;
};
How do I zero out `c' and `d'?
next prev parent reply other threads:[~2021-12-08 4:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 3:04 [PATCH -next 0/2] Introduce memset_range() helper for wiping members Xiu Jianfeng
2021-12-08 3:04 ` [PATCH -next 1/2] string.h: Introduce memset_range() " Xiu Jianfeng
2021-12-08 4:28 ` Andrew Morton [this message]
2021-12-08 10:30 ` xiujianfeng
2021-12-08 23:44 ` Andrew Morton
2021-12-09 5:17 ` Kees Cook
2021-12-09 6:29 ` xiujianfeng
2021-12-09 6:29 ` xiujianfeng
2021-12-08 17:12 ` Alexey Dobriyan
2021-12-08 3:04 ` [PATCH -next 2/2] bpf: use memset_range helper in __mark_reg_known Xiu Jianfeng
2021-12-08 5:27 ` [PATCH -next 0/2] Introduce memset_range() helper for wiping members Kees Cook
2021-12-08 10:30 ` xiujianfeng
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