From 5b08560181b513984e73372b2766eeac7aa39d1b Mon Sep 17 00:00:00 2001
From: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Date: Tue, 30 Nov 2021 21:48:36 -0800
Subject: [PATCH] ibmvnic: drop bad optimization in reuse_tx_pools()

References: bsc#1193349 ltc#195568
Patch-mainline: v5.16 or v5.16-rc4 (next release)
Git-commit: 5b08560181b513984e73372b2766eeac7aa39d1b

When trying to decide whether or not reuse existing rx/tx pools
we tried to allow a range of values for the pool parameters rather
than exact matches. This was intended to reuse the resources for
instance when switching between two VIO servers with different
default parameters.

But this optimization is incomplete and breaks when we try to
change the number of queues for instance. The optimization needs
to be updated, so drop it for now and simplify the code.

Fixes: bbd809305bc7 ("ibmvnic: Reuse tx pools when possible")
Reported-by: Dany Madden <drt@linux.ibm.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Reviewed-by: Dany Madden <drt@linux.ibm.com>
Reviewed-by: Rick Lindsley <ricklind@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 6df92a872f0f..0bb3911dd014 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -866,17 +866,9 @@ static bool reuse_tx_pools(struct ibmvnic_adapter *adapter)
 	old_mtu = adapter->prev_mtu;
 	new_mtu = adapter->req_mtu;
 
-	/* Require MTU to be exactly same to reuse pools for now */
-	if (old_mtu != new_mtu)
-		return false;
-
-	if (old_num_pools == new_num_pools && old_pool_size == new_pool_size)
-		return true;
-
-	if (old_num_pools < adapter->min_tx_queues ||
-	    old_num_pools > adapter->max_tx_queues ||
-	    old_pool_size < adapter->min_tx_entries_per_subcrq ||
-	    old_pool_size > adapter->max_tx_entries_per_subcrq)
+	if (old_mtu != new_mtu ||
+	    old_num_pools != new_num_pools ||
+	    old_pool_size != new_pool_size)
 		return false;
 
 	return true;
-- 
2.31.1