After commit 7f56b58a92aaf2c ("locking/mcs: Use smp_cond_load_acquire()
in MCS spin loop") Loongson-3 fails to boot. This is because Loongson-3
has SFB (Store Fill Buffer) and need a mb() after every READ_ONCE().
This patch introduce a MIPS-specific mcs_spinlock.h and revert to the
old implementation of arch_mcs_spin_lock_contended() for Loongson-3.
Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
---
arch/mips/include/asm/Kbuild | 1 -
arch/mips/include/asm/mcs_spinlock.h | 14 ++++++++++++++
2 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 arch/mips/include/asm/mcs_spinlock.h
diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index 45d541b..7076627 100644
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -6,7 +6,6 @@ generic-y += emergency-restart.h
generic-y += export.h
generic-y += irq_work.h
generic-y += local64.h
-generic-y += mcs_spinlock.h
generic-y += mm-arch-hooks.h
generic-y += parport.h
generic-y += percpu.h
diff --git a/arch/mips/include/asm/mcs_spinlock.h b/arch/mips/include/asm/mcs_spinlock.h
new file mode 100644
index 0000000..063df4e
--- /dev/null
+++ b/arch/mips/include/asm/mcs_spinlock.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MCS_LOCK_H
+#define __ASM_MCS_LOCK_H
+
+/* Loongson-3 need a mb() after every READ_ONCE() */
+#if defined(CONFIG_CPU_LOONGSON3) && defined(CONFIG_SMP)
+#define arch_mcs_spin_lock_contended(l) \
+do { \
+ while (!(smp_load_acquire(l))) \
+ cpu_relax(); \
+} while (0)
+#endif /* CONFIG_CPU_LOONGSON3 && CONFIG_SMP */
+
+#endif /* __ASM_MCS_LOCK_H */
--
2.7.0
