From 007b656851ed7f94ba0fa358ac3e5d7705da6846 Mon Sep 17 00:00:00 2001
From: Ursula Braun <ubraun@linux.ibm.com>
Date: Mon, 12 Nov 2018 17:06:12 +0100
Subject: [PATCH] s390/ism: clear dmbe_mask bit before SMC IRQ handling
SMC-D stress workload showed connection stalls. Since the firmware
decides to skip raising an interrupt if the SBA DMBE mask bit is
still set, this SBA DMBE mask bit should be cleared before the
IRQ handling in the SMC code runs. Otherwise there are small windows
possible with missing interrupts for incoming data.
SMC-D currently does not care about the old value of the SBA DMBE
mask.
Acked-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/s390/net/ism_drv.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/s390/net/ism_drv.c b/drivers/s390/net/ism_drv.c
index f96ec68af2e58..dcbf5c8577437 100644
--- a/drivers/s390/net/ism_drv.c
+++ b/drivers/s390/net/ism_drv.c
@@ -415,9 +415,9 @@ static irqreturn_t ism_handle_irq(int irq, void *data)
break;
clear_bit_inv(bit, bv);
+ ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET] = 0;
barrier();
smcd_handle_irq(ism->smcd, bit + ISM_DMB_BIT_OFFSET);
- ism->sba->dmbe_mask[bit + ISM_DMB_BIT_OFFSET] = 0;
}
if (ism->sba->e) {
--
2.30.2