Message ID | 20230119143619.2733236-7-vschneid@redhat.com (mailing list archive) |
---|---|
State | Handled Elsewhere |
Headers | show
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Thu, 19 Jan 2023 14:37:27 +0000 (UTC) Received: from vschneid.remote.csb (unknown [10.33.36.13]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9C6872026D68; Thu, 19 Jan 2023 14:37:22 +0000 (UTC) From: Valentin Schneider <vschneid@redhat.com> To: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, x86@kernel.org Subject: [PATCH v4 6/7] smp: reword smp call IPI comment Date: Thu, 19 Jan 2023 14:36:18 +0000 Message-Id: <20230119143619.2733236-7-vschneid@redhat.com> In-Reply-To: <20230119143619.2733236-1-vschneid@redhat.com> References: <20230119143619.2733236-1-vschneid@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org> List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>, <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe> List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/> List-Post: <mailto:linuxppc-dev@lists.ozlabs.org> List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help> List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>, <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe> Cc: Juri Lelli <juri.lelli@redhat.com>, Mark Rutland <mark.rutland@arm.com>, Dave Hansen <dave.hansen@linux.intel.com>, "Paul E. McKenney" <paulmck@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Marc Zyngier <maz@kernel.org>, Sebastian Andrzej Siewior <bigeasy@linutronix.de>, Marcelo Tosatti <mtosatti@redhat.com>, Russell King <linux@armlinux.org.uk>, Steven Rostedt <rostedt@goodmis.org>, "David S. Miller" <davem@davemloft.net>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Nicholas Piggin <npiggin@gmail.com>, "H. Peter Anvin" <hpa@zytor.com>, Guo Ren <guoren@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Daniel Bristot de Oliveira <bristot@redhat.com>, Frederic Weisbecker <frederic@kernel.org> Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" <linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org> |
Series |
Generic IPI sending tracepoint
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expand
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diff --git a/kernel/smp.c b/kernel/smp.c index 93b4386cd3096..821b5986721ac 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -495,9 +495,10 @@ void __smp_call_single_queue(int cpu, struct llist_node *node) #endif /* - * The list addition should be visible before sending the IPI - * handler locks the list to pull the entry off it because of - * normal cache coherency rules implied by spinlocks. + * The list addition should be visible to the target CPU when it pops + * the head of the list to pull the entry off it in the IPI handler + * because of normal cache coherency rules implied by the underlying + * llist ops. * * If IPIs can go out of order to the cache coherency protocol * in an architecture, sufficient synchronisation should be added
Accessing the call_single_queue hasn't involved a spinlock since 2014: 6897fc22ea01 ("kernel: use lockless list for smp_call_function_single") The llist operations (namely cmpxchg() and xchg()) provide similar ordering guarantees, update the comment to lessen confusion. Signed-off-by: Valentin Schneider <vschneid@redhat.com> --- kernel/smp.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)