linux-kernel - Re: [PATCH v3 1/3] lib: bitmap: introduce bitmap_print_to

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Date:   Thu, 3 Jun 2021 18:33:25 +0800
From:   "tiantao (H)" <tiantao6@...wei.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Tian Tao <tiantao6@...ilicon.com>
CC:     <gregkh@...uxfoundation.org>, <rafael@...nel.org>,
        <akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>,
        <jonathan.cameron@...wei.com>, <song.bao.hua@...ilicon.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Stefano Brivio <sbrivio@...hat.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        "Ma, Jianpeng" <jianpeng.ma@...el.com>,
        Yury Norov <yury.norov@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Daniel Bristot de Oliveira <bristot@...hat.com>
Subject: Re: [PATCH v3 1/3] lib: bitmap: introduce bitmap_print_to_buf


在 2021/6/3 17:50, Andy Shevchenko 写道:
> On Thu, Jun 03, 2021 at 05:22:40PM +0800, Tian Tao wrote:
>> New API bitmap_print_to_buf() with bin_attribute to avoid maskp
>> exceeding PAGE_SIZE. bitmap_print_to_pagebuf() is a special case
>> of bitmap_print_to_buf(), so in bitmap_print_to_pagebuf() call
>> bitmap_print_to_buf().
> ...
>
>>   /**
>> + * bitmap_print_to_buf - convert bitmap to list or hex format ASCII string
>> + * @list: indicates whether the bitmap must be list
>> + * @buf: the kernel space buffer to read to
>> + * @maskp: pointer to bitmap to convert
>> + * @nmaskbits: size of bitmap, in bits
>> + * @off: offset in data buffer below
>> + * @count: the maximum number of bytes to print
>> + *
>> + * The role of bitmap_print_to_buf() and bitmap_print_to_pagebuf() is
>> + * the same, the difference is that buf of bitmap_print_to_buf()
>> + * can be more than one pagesize.
>> + */
>> +int bitmap_print_to_buf(bool list, char *buf, const unsigned long *maskp,
>> +			int nmaskbits, loff_t off, size_t count)
>> +{
>> +	const char *fmt = list ? "%*pbl\n" : "%*pb\n";
>> +	ssize_t size;
>> +	void *data;
>> +
>> +	if (off == LLONG_MAX && count == PAGE_SIZE - offset_in_page(buf))
>> +		return scnprintf(buf, count, fmt, nmaskbits, maskp);
>> +
>> +	data = kasprintf(GFP_KERNEL, fmt, nmaskbits, maskp);
>> +	if (!data)
>> +		return -ENOMEM;
>> +
>> +	size = memory_read_from_buffer(buf, count, &off, data, strlen(data) + 1);
> Are you sure you have put parameters in the correct order?

yes, I already test it.

ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
                                 const void *from, size_t available)

>
>> +	kfree(data);
>> +
>> +	return size;
>> +}
> I guess you have to provide the test case(s).
>