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From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@kernel.org>, Linux-MM <linux-mm@kvack.org>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH v3 3/3] bootconfig: Free xbc_data in xbc_destroy_all()
Date: Wed, 15 Sep 2021 10:23:54 -0400	[thread overview]
Message-ID: <20210915102354.2841798d@oasis.local.home> (raw)
In-Reply-To: <163171199244.590070.6356174550728998874.stgit@devnote2>

On Wed, 15 Sep 2021 22:19:52 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:

> @@ -810,6 +811,8 @@ void __init xbc_destroy_all(void)
>   * In error cases, @emsg will be updated with an error message and
>   * @epos will be updated with the error position which is the byte offset
>   * of @buf. If the error is not a parser error, @epos will be -1.
> + * Note that the @buf ownership is transferred, so it will be freed
> + * in xbc_destroy_all().
>   */
>  int __init xbc_init(char *buf, const char **emsg, int *epos)
>  {

I hate this "ownership transfer". Looking at the use case here:

init/main.c:

	copy = memblock_alloc(size + 1, SMP_CACHE_BYTES);
	if (!copy) {
		pr_err("Failed to allocate memory for bootconfig\n");
		return;
	}

	memcpy(copy, data, size);
	copy[size] = '\0';

	ret = xbc_init(copy, &msg, &pos);
	if (ret < 0) {

Instead of having xbc_init() return the node count on success, how about
having it allocate the buffer to use and then return it?

That is, move the:

	copy = memblock_alloc(size + 1, SMP_CACHE_BYTES);
	if (!copy) {
		pr_err("Failed to allocate memory for bootconfig\n");
		return;
	}

	memcpy(copy, data, size);
	copy[size] = '\0';

into xbc_init(), and have data, and size be passed to it.

Then, have it return the pointer of "copy" or NULL on error?

This will keep the semantics of xbc_* owning the buffer that gets
freed by the destroy.

The xbc_init() could also do the pr_info() that prints the bytes and
node count. There's no other reason to pass that node count to the
caller, is there?

-- Steve

  reply	other threads:[~2021-09-15 14:24 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-15 13:19 [PATCH v3 0/3] bootconfig: Fixes to bootconfig memory management Masami Hiramatsu
2021-09-15 13:19 ` [PATCH v3 1/3] bootconfig: init: Fix memblock leak in xbc_make_cmdline() Masami Hiramatsu
2021-09-15 13:19 ` [PATCH v3 2/3] bootconfig: init: Fix memblock leak in setup_boot_config() Masami Hiramatsu
2021-09-15 13:19 ` [PATCH v3 3/3] bootconfig: Free xbc_data in xbc_destroy_all() Masami Hiramatsu
2021-09-15 14:23   ` Steven Rostedt [this message]
2021-09-16  0:05     ` Masami Hiramatsu
2021-09-16  0:17       ` Steven Rostedt
2021-09-15 16:47 ` [PATCH v3 0/3] bootconfig: Fixes to bootconfig memory management Linus Torvalds
2021-09-15 16:51   ` Linus Torvalds
2021-09-16  0:07     ` Masami Hiramatsu

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