* [PATCH RFC v2 rcu 7/8] arch/loongarch: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option
[not found] <20220929180714.GA2874192@paulmck-ThinkPad-P17-Gen-1>
@ 2022-09-29 18:07 ` Paul E. McKenney
0 siblings, 0 replies; only message in thread
From: Paul E. McKenney @ 2022-09-29 18:07 UTC (permalink / raw)
To: rcu
Cc: linux-kernel, kernel-team, rostedt, Paul E. McKenney,
Neeraj Upadhyay, Frederic Weisbecker, Boqun Feng, Huacai Chen,
WANG Xuerui, Thomas Gleixner, John Ogness, Petr Mladek, loongarch
The loongarch architecture uses the atomic read-modify-write amadd
instruction to implement this_cpu_add(), which is NMI safe. This means
that the old and more-efficient srcu_read_lock() may be used in NMI
context, without the need for srcu_read_lock_nmisafe(). Therefore, add
the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/x86/Kconfig,
which will cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving
the current srcu_read_lock() behavior.
Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/
Suggested-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Petr Mladek <pmladek@suse.com>
Cc: <loongarch@lists.linux.dev>
---
arch/loongarch/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 4abc9a28aba4..c8864768dc4d 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -10,6 +10,7 @@ config LOONGARCH
select ARCH_ENABLE_MEMORY_HOTPLUG
select ARCH_ENABLE_MEMORY_HOTREMOVE
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
+ select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS
select ARCH_HAS_PHYS_TO_DMA
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
--
2.31.1.189.g2e36527f23
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