linux-kernel - Re: [PATCH 1/2] lib/string_helpers: Introduce strsplit

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Date:   Sat, 9 Jul 2022 10:45:49 +0200
From:   Cezary Rojewski <cezary.rojewski@...el.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Péter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
        "Andy Shevchenko" <andy@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        "ALSA Development Mailing List" <alsa-devel@...a-project.org>,
        Takashi Iwai <tiwai@...e.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        <amadeuszx.slawinski@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        "Kai Vehmanen" <kai.vehmanen@...ux.intel.com>,
        Bard Liao <yung-chuan.liao@...ux.intel.com>
Subject: Re: [PATCH 1/2] lib/string_helpers: Introduce strsplit_u32()

On 2022-07-08 6:49 PM, Andy Shevchenko wrote:
> On Fri, Jul 8, 2022 at 6:32 PM Cezary Rojewski
> <cezary.rojewski@...el.com> wrote:
>>
>> On 2022-07-08 5:25 PM, Andy Shevchenko wrote:
>>> On Fri, Jul 8, 2022 at 2:34 PM Péter Ujfalusi
>>> <peter.ujfalusi@...ux.intel.com> wrote:
> 
>> A long shot, but what if we were to modify get_options() so it takes
>> additional element-size parameter instead?
> 
> But why? int / unsigned int, u32 / s32  are all compatible in the current cases.

I'd like to avoid any additional operations, so that the retrieved 
payload can be provided to the IPC handler directly. The IPC handlers 
for AudioDSP drivers are expecting payload in u32s.

// u32 **tkns, size_t *num_tkns as foo() arguments
// u32 *ints, int nints as locals

	get_options(buf, 0, &nints);
	if (!nints) {
		ret = -ENOENT;
		goto free_buf;
	}

	ints = kcalloc(nints + 1, sizeof(*ints), GFP_KERNEL);
	if (!ints) {
		ret = -ENOMEM;
		goto free_buf;
	}

	get_num_options(buf, nints + 1, ints, sizeof(*ints));

	*tkns = ints;
	*num_tkns = nints;

No additional operations in between. The intermediate IPC handler can 
later refer to the actual payload via &tkns[1] before passing it to the 
generic one.

Casting int array into u32 array does not feel right, or perhaps I'm 
missing something like in the doc case.


Regards,
Czarek