Commit 29b1ee87 authored by Konstantin Khorenko's avatar Konstantin Khorenko Committed by Jakub Kicinski
Browse files

net: add noinline __init __no_profile to skb_extensions_init() for GCOV compatibility 



With -fprofile-update=atomic in global CFLAGS_GCOV, GCC still cannot
constant-fold the skb_ext_total_length() loop when it is inlined into a
profiled caller.  The existing __no_profile on skb_ext_total_length()
itself is insufficient because after __always_inline expansion the code
resides in the caller's body, which still carries GCOV instrumentation.

Mark skb_extensions_init() with __no_profile so the BUILD_BUG_ON checks
can be evaluated at compile time.  Also mark it noinline to prevent the
compiler from inlining it into skb_init() (which lacks __no_profile),
which would re-expose the function body to GCOV instrumentation.

Add __init since skb_extensions_init() is only called from __init
skb_init().  Previously it was implicitly inlined into the .init.text
section; with noinline it would otherwise remain in permanent .text,
wasting memory after boot.

Build-tested with both CONFIG_GCOV_PROFILE_ALL=y and
CONFIG_KCOV_INSTRUMENT_ALL=y.

Signed-off-by: default avatarKonstantin Khorenko <khorenko@virtuozzo.com>
Link: https://patch.msgid.link/20260410162150.3105738-3-khorenko@virtuozzo.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c0b4382c

net/core/skbuff.c

+1 −1
Original line number Diff line number Diff line
@@ -5129,7 +5129,7 @@ static __always_inline __no_profile unsigned int skb_ext_total_length(void) 
	return l;

}



static void skb_extensions_init(void)

static noinline void __init __no_profile skb_extensions_init(void)

{

	BUILD_BUG_ON(SKB_EXT_NUM > 8);

	BUILD_BUG_ON(skb_ext_total_length() > 255);