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kbuild: use $(CFLAGS_GCOV) in the prefer-atomic try-run test

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Patch series "kbuild: GCOV cleanups following the prefer-atomic fix".

Two cleanups Peter Oberparleiter suggested while reviewing commit
56cb9b7d96 ("gcov: use atomic counter updates to fix concurrent access
crashes"):

https://lore.kernel.org/e1b6e768-51af-468b-a729-0ed3fceef2f1@linux.ibm.com

Patch 1 makes the prefer-atomic try-run test reuse $(CFLAGS_GCOV) instead
of spelling the flags out again, so the test compiles with the exact GCOV
flags, -fno-tree-loop-im included.

Patch 2 moves the CFLAGS_GCOV block into scripts/Makefile.gcov, included
via include-$(CONFIG_GCOV_KERNEL) like the other instrumentation
makefiles.  The try-run also stops running on builds without GCOV.


This patch (of 2):

Reference $(CFLAGS_GCOV) in the try-run test introduced by
commit 56cb9b7d96 ("gcov: use atomic counter updates to fix
concurrent access crashes"), otherwise it can miss potential future
changes in the list of flags used for GCOV profiling like it misses
-fno-tree-loop-im at the moment.

The outcome of the test is unchanged: -fno-tree-loop-im does not affect
the undefined symbols the test compares.

Link: https://lore.kernel.org/20261001-b4-prep-gcov-v1-0-794792e06f24@virtuozzo.com
Link: https://lore.kernel.org/20261001-b4-prep-gcov-v1-1-794792e06f24@virtuozzo.com
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nsc@kernel.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Mikhail Zaslonko <zaslonko@linux.ibm.com>
This commit is contained in:
Konstantin Khorenko 2026-10-01 18:57:11 +02:00 committed by Andrew Morton
parent a7f476e262
commit 4719c92641
1 changed files with 4 additions and 4 deletions
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8
Makefile
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@ -1184,11 +1184,11 @@ CFLAGS_GCOV += -fno-tree-loop-im
# undefined symbols (e.g. libatomic calls that the kernel cannot link).
CFLAGS_GCOV += $(call try-run,\
echo 'long long x; void f(void){x++;}' | \
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -w -fprofile-arcs \
-ftest-coverage -x c - -c -o "$$TMP.base" && \
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -w $(CFLAGS_GCOV) \
-x c - -c -o "$$TMP.base" && \
echo 'long long x; void f(void){x++;}' | \
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -w -fprofile-arcs \
-ftest-coverage -fprofile-update=prefer-atomic \
$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -w $(CFLAGS_GCOV) \
-fprofile-update=prefer-atomic \
-x c - -c -o "$$TMP" && \
$(NM) "$$TMP.base" | grep ' U ' > "$$TMP.ubase" || true ; \
$(NM) "$$TMP" | grep ' U ' > "$$TMP.utest" || true ; \