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Mon, 11 May 2026 07:49:37 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: AYkZ7v-3APXo Date: Mon, 11 May 2026 13:48:55 +0200 From: "Arnd Bergmann" To: "Konstantin Khorenko" , "Andrew Morton" , "Peter Oberparleiter" Cc: "Nathan Chancellor" , "Nicolas Schier" , "Mikhail Zaslonko" , =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= , "Miguel Ojeda" , "Masahiro Yamada" , "Vasileios Almpanis" , "Pavel Tikhomirov" , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org Message-Id: In-Reply-To: <20260511105052.417187-2-khorenko@virtuozzo.com> References: <20260511105052.417187-1-khorenko@virtuozzo.com> <20260511105052.417187-2-khorenko@virtuozzo.com> Subject: Re: [PATCH v4 1/1] gcov: use atomic counter updates to fix concurrent access crashes Content-Type: text/plain Content-Transfer-Encoding: 7bit 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 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