riscv/barrier: Define __smp_{store_release,load_acquire}

Introduce __smp_{store_release,load_acquire}, and rely on the generic
definitions for smp_{store_release,load_acquire}. This avoids the use
of full ("rw,rw") fences on SMP.

Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

diff --git a/arch/riscv/include/asm/barrier.h b/arch/riscv/include/asm/barrier.h
index 5510366d169aea821e9f09ffe613363a2009db93..d4628e4b3a5ea044a54e8debb8ed7b0b970ed2be 100644 (file)
--- a/arch/riscv/include/asm/barrier.h
+++ b/arch/riscv/include/asm/barrier.h
@@ -38,6 +38,21 @@
 #define __smp_rmb()    RISCV_FENCE(r,r)
 #define __smp_wmb()    RISCV_FENCE(w,w)
 
+#define __smp_store_release(p, v)                                      \
+do {                                                                   \
+       compiletime_assert_atomic_type(*p);                             \
+       RISCV_FENCE(rw,w);                                              \
+       WRITE_ONCE(*p, v);                                              \
+} while (0)
+
+#define __smp_load_acquire(p)                                          \
+({                                                                     \
+       typeof(*p) ___p1 = READ_ONCE(*p);                               \
+       compiletime_assert_atomic_type(*p);                             \
+       RISCV_FENCE(r,rw);                                              \
+       ___p1;                                                          \
+})
+
 /*
  * This is a very specific barrier: it's currently only used in two places in
  * the kernel, both in the scheduler.  See include/linux/spinlock.h for the two