riscv: Match memory barriers between send_ipi_many and handle_ipi

Without a matching barrier on the write side, the barrier in handle_ipi
does nothing. It was entirely possible for the boot hart to write to addr,
arg0, and arg1 *after* sending the IPI, because there was no barrier on the
sending side.

Fixes: 90ae281437 ("riscv: add option to wait for ack from secondary harts in smp functions")
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Rick Chen <rick@andestech.com>
Reviewed-by: Leo Liang <ycliang@andestech.com>

diff --git a/arch/riscv/lib/smp.c b/arch/riscv/lib/smp.c
index ac22136..ab6d8bd 100644 (file)
--- a/arch/riscv/lib/smp.c
+++ b/arch/riscv/lib/smp.c
@@ -54,6 +54,8 @@ static int send_ipi_many(struct ipi_data *ipi, int wait)
                gd->arch.ipi[reg].arg0 = ipi->arg0;
                gd->arch.ipi[reg].arg1 = ipi->arg1;
 
+               __smp_mb();
+
                ret = riscv_send_ipi(reg);
                if (ret) {
                        pr_err("Cannot send IPI to hart %d\n", reg);