+ kbuild-use-cflags_gcov-in-the-prefer-atomic-try-run-test.patch added to mm-nonmm-unstable branch

+ kbuild-use-cflags_gcov-in-the-prefer-atomic-try-run-test.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: kbuild: use $(CFLAGS_GCOV) in the prefer-atomic try-run test
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     kbuild-use-cflags_gcov-in-the-prefer-atomic-try-run-test.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kbuild-use-cflags_gcov-in-the-prefer-atomic-try-run-test.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Konstantin Khorenko <khorenko@virtuozzo.com>
Subject: kbuild: use $(CFLAGS_GCOV) in the prefer-atomic try-run test
Date: Thu, 01 Oct 2026 18:57:11 +0200

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

Two cleanups Peter Oberparleiter suggested while reviewing commit
56cb9b7d96b2 ("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 56cb9b7d96b2 ("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>
---

 Makefile |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/Makefile~kbuild-use-cflags_gcov-in-the-prefer-atomic-try-run-test
+++ a/Makefile
@@ -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 ; \
_

Patches currently in -mm which might be from khorenko@virtuozzo.com are

selftests-core-fix-unshare_test-with-large-fsnr_open.patch
kbuild-use-cflags_gcov-in-the-prefer-atomic-try-run-test.patch
kbuild-move-gcov-flags-to-scripts-makefilegcov.patch