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    Subject[PATCH v3 rcu 07/11] arch/loongarch: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option
    Date
    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 903096bd87f88..386adde2feffb 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_PTE_SPECIAL
    select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
    select ARCH_INLINE_READ_LOCK if !PREEMPTION
    --
    2.31.1.189.g2e36527f23
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