Re: [PATCH v2] libfdt: Don't search for the terminator in fdt_get_string()

[David Gibson <david@gibson.dropbear.id.au>]

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On Sun, Nov 01, 2026 at 08:50:05PM -0800, Kelvin Zhang wrote:
> Unless FDT_ASSUME_MASK includes ASSUME_VALID_INPUT, fdt_get_string()
> finds the end of the string with memchr(), bounded by the end of the
> string block, which also checks that the string is terminated. A
> string block normally ends with a NUL, and then every string in it is
> terminated. When the caller does not ask for the string's length,
> check that byte instead, so that fdt_string() doesn't scan the string
> at all.
> 
> This helps callers that look up many property names. With a 612 KiB
> tree on x86-64, built with gcc -O2 and the default FDT_ASSUME_MASK,
> calling fdt_string() for the name of each of its 17,899 properties
> takes 108 us instead of 160 us, not counting the walk that finds
> them. libufdt, which Android bootloaders use to apply overlays, calls
> fdt_string() at least once for every property it reads: tens of
> thousands of times to apply one overlay to a 445 KiB tree.
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Kelvin Zhang <zhangkelvin@google.com>

Merged, thanks.

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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