netdev - [PATCH v2 net-next 1/8] net/ncsi: Disable HWA mode when no channels are found

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Message-Id: <1492069701-20772-2-git-send-email-gwshan@linux.vnet.ibm.com>
Date:   Thu, 13 Apr 2017 17:48:14 +1000
From:   Gavin Shan <gwshan@...ux.vnet.ibm.com>
To:     netdev@...r.kernel.org
Cc:     joe@...ches.com, davem@...emloft.net,
        Gavin Shan <gwshan@...ux.vnet.ibm.com>
Subject: [PATCH v2 net-next 1/8] net/ncsi: Disable HWA mode when no channels are found

When there are no NCSI channels probed, HWA (Hardware Arbitration)
mode is enabled. It's not correct because HWA depends on the fact:
NCSI channels exist and all of them support HWA mode. This disables
HWA when no channels are probed.

Signed-off-by: Gavin Shan <gwshan@...ux.vnet.ibm.com>
---
 net/ncsi/ncsi-manage.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/ncsi/ncsi-manage.c b/net/ncsi/ncsi-manage.c
index a3bd5fa..5073e15 100644
--- a/net/ncsi/ncsi-manage.c
+++ b/net/ncsi/ncsi-manage.c
@@ -839,12 +839,15 @@ static bool ncsi_check_hwa(struct ncsi_dev_priv *ndp)
 	struct ncsi_package *np;
 	struct ncsi_channel *nc;
 	unsigned int cap;
+	bool has_channel = false;
 
 	/* The hardware arbitration is disabled if any one channel
 	 * doesn't support explicitly.
 	 */
 	NCSI_FOR_EACH_PACKAGE(ndp, np) {
 		NCSI_FOR_EACH_CHANNEL(np, nc) {
+			has_channel = true;
+
 			cap = nc->caps[NCSI_CAP_GENERIC].cap;
 			if (!(cap & NCSI_CAP_GENERIC_HWA) ||
 			    (cap & NCSI_CAP_GENERIC_HWA_MASK) !=
@@ -855,8 +858,13 @@ static bool ncsi_check_hwa(struct ncsi_dev_priv *ndp)
 		}
 	}
 
-	ndp->flags |= NCSI_DEV_HWA;
-	return true;
+	if (has_channel) {
+		ndp->flags |= NCSI_DEV_HWA;
+		return true;
+	}
+
+	ndp->flags &= ~NCSI_DEV_HWA;
+	return false;
 }
 
 static int ncsi_enable_hwa(struct ncsi_dev_priv *ndp)
-- 
2.7.4