Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH v3 rcu 08/11] arch/s390: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option | Date | Wed, 19 Oct 2022 15:58:43 -0700 |
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The s390 architecture uses either a cmpxchg loop (old systems) or the laa add-to-memory instruction (new systems) to implement this_cpu_add(), both of which are 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/arm64/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: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Ogness <john.ogness@linutronix.de> Cc: Petr Mladek <pmladek@suse.com> Cc: <linux-s390@vger.kernel.org> --- arch/s390/Kconfig | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 318fce77601d3..0acdfda332908 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -73,6 +73,7 @@ config S390 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_MEM_ENCRYPT + select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_SCALED_CPUTIME select ARCH_HAS_SET_MEMORY -- 2.31.1.189.g2e36527f23
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