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bitmap: extend comment to bitmap_print_bitmask/list_to_buf
Extend comment to new function to warn potential users about caveats. Signed-off-by: Yury Norov <yury.norov@gmail.com> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Link: https://lore.kernel.org/r/20210806110251.560-6-song.bao.hua@hisilicon.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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lib/bitmap.c
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lib/bitmap.c
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@ -568,6 +568,24 @@ static int bitmap_print_to_buf(bool list, char *buf, const unsigned long *maskp,
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* and it can break the size limit of converted decimal list and hexadecimal
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* and it can break the size limit of converted decimal list and hexadecimal
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* bitmask.
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* bitmask.
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*
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*
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* WARNING!
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*
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* This function is not a replacement for sprintf() or bitmap_print_to_pagebuf().
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* It is intended to workaround sysfs limitations discussed above and should be
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* used carefully in general case for the following reasons:
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* - Time complexity is O(nbits^2/count), comparing to O(nbits) for snprintf().
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* - Memory complexity is O(nbits), comparing to O(1) for snprintf().
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* - @off and @count are NOT offset and number of bits to print.
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* - If printing part of bitmap as list, the resulting string is not a correct
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* list representation of bitmap. Particularly, some bits within or out of
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* related interval may be erroneously set or unset. The format of the string
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* may be broken, so bitmap_parselist-like parser may fail parsing it.
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* - If printing the whole bitmap as list by parts, user must ensure the order
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* of calls of the function such that the offset is incremented linearly.
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* - If printing the whole bitmap as list by parts, user must keep bitmap
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* unchanged between the very first and very last call. Otherwise concatenated
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* result may be incorrect, and format may be broken.
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*
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* Returns the number of characters actually printed to @buf
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* Returns the number of characters actually printed to @buf
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*/
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*/
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int bitmap_print_bitmask_to_buf(char *buf, const unsigned long *maskp,
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int bitmap_print_bitmask_to_buf(char *buf, const unsigned long *maskp,
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