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[v3,2/7] riscv: Match memory barriers between send_ipi_many and handle_ipi

Message ID 20200921115141.70598-3-seanga2@gmail.com
State Accepted
Commit d4990a46485f2f6592ae29f2b822043dbdeae15d
Delegated to: Andes
Headers show
Series riscv: Correctly handle IPIs already pending upon boot | expand

Commit Message

Sean Anderson Sept. 21, 2020, 11:51 a.m. UTC
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>

(no changes since v1)

 arch/riscv/lib/smp.c | 2 ++
 1 file changed, 2 insertions(+)
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diff --git a/arch/riscv/lib/smp.c b/arch/riscv/lib/smp.c
index ac22136314..ab6d8bd7fa 100644
--- 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);