From: "Arnd Bergmann" <arnd@arndb.de>
To: "Konstantin Khorenko" <khorenko@virtuozzo.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Peter Oberparleiter" <oberpar@linux.ibm.com>
Cc: "Nathan Chancellor" <nathan@kernel.org>,
"Nicolas Schier" <nsc@kernel.org>,
"Mikhail Zaslonko" <zaslonko@linux.ibm.com>,
"Thomas Weißschuh" <linux@weissschuh.net>,
"Miguel Ojeda" <ojeda@kernel.org>,
"Masahiro Yamada" <masahiroy@kernel.org>,
"Vasileios Almpanis" <vasileios.almpanis@virtuozzo.com>,
"Pavel Tikhomirov" <ptikhomirov@virtuozzo.com>,
linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org
Subject: Re: [PATCH v4 1/1] gcov: use atomic counter updates to fix concurrent access crashes
Date: Mon, 11 May 2026 13:48:55 +0200 [thread overview]
Message-ID: <f6165240-a3b9-4612-8d25-d8ba3c36f42a@app.fastmail.com> (raw)
In-Reply-To: <20260511105052.417187-2-khorenko@virtuozzo.com>
On Mon, May 11, 2026, at 12:50, Konstantin Khorenko wrote:
> On architectures where GCC inlines 64-bit atomic counter updates
> (x86_64, s390, ...) the test passes and the flag is enabled, preventing
> the compiler from merging counters with loop induction variables and
> fixing the observed concurrent-access crash.
>
> On architectures where the flag would introduce libatomic dependencies,
> it is silently omitted and behaviour is no worse than before this patch.
Tested-by: Arnd Bergmann <arnd@arndb.de>
I've checked this with my cross compilers now, and found the
external function calls on aarch64, csky, and hppa. On x86-64,
the trivial scripts did not reproduce that unless I also pass
"-m32 -msoft-float -mno-sse", which is what you get from
KBUILD_CFLAGS.
Arnd
next prev parent reply other threads:[~2026-05-11 11:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-11 10:50 [PATCH v4 0/1] gcov: use -fprofile-update=prefer-atomic with compile-time guard Konstantin Khorenko
2026-05-11 10:50 ` [PATCH v4 1/1] gcov: use atomic counter updates to fix concurrent access crashes Konstantin Khorenko
2026-05-11 11:48 ` Arnd Bergmann [this message]
2026-05-13 9:15 ` Peter Oberparleiter
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