netdev - [PATCH V1 net 2/3] net: ena: Change WARN_ON expression in ena_del_napi_in

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Message-ID: <20200812101059.5501-3-shayagr@amazon.com>
Date:   Wed, 12 Aug 2020 13:10:58 +0300
From:   Shay Agroskin <shayagr@...zon.com>
To:     <davem@...emloft.net>, <netdev@...r.kernel.org>
CC:     <dwmw@...zon.com>, <zorik@...zon.com>, <matua@...zon.com>,
        <saeedb@...zon.com>, <msw@...zon.com>, <aliguori@...zon.com>,
        <nafea@...zon.com>, <gtzalik@...zon.com>, <netanel@...zon.com>,
        <alisaidi@...zon.com>, <benh@...zon.com>, <akiyano@...zon.com>,
        <sameehj@...zon.com>, <ndagan@...zon.com>,
        Shay Agroskin <shayagr@...zon.com>
Subject: [PATCH V1 net 2/3] net: ena: Change WARN_ON expression in ena_del_napi_in_range()

The ena_del_napi_in_range() function unregisters the napi handler for
rings in a given range.
This function had the following WARN_ON macro:

    WARN_ON(ENA_IS_XDP_INDEX(adapter, i) &&
	    adapter->ena_napi[i].xdp_ring);

This macro prints the call stack if the expression inside of it is
true [1], but the expression inside of it is the wanted situation.
The expression checks whether the ring has an XDP queue and its index
corresponds to a XDP one.

This patch changes the expression to
    !ENA_IS_XDP_INDEX(adapter, i) && adapter->ena_napi[i].xdp_ring
which indicates an unwanted situation.

Also, change the structure of the function. The napi handler is
unregistered for all rings, and so there's no need to check whether the
index is an XDP index or not. By removing this check the code becomes
much more readable.

[1]:
https://elixir.bootlin.com/linux/latest/source/arch/parisc/include/asm/bug.h#L79

Fixes: 8c5c7abdeb2d ("net: ena: add power management ops to the ENA driver")
Signed-off-by: Shay Agroskin <shayagr@...zon.com>
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 0488fcbf48f7..3e12065482c2 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -2180,13 +2180,10 @@ static void ena_del_napi_in_range(struct ena_adapter *adapter,
 	int i;
 
 	for (i = first_index; i < first_index + count; i++) {
-		/* Check if napi was initialized before */
-		if (!ENA_IS_XDP_INDEX(adapter, i) ||
-		    adapter->ena_napi[i].xdp_ring)
-			netif_napi_del(&adapter->ena_napi[i].napi);
-		else
-			WARN_ON(ENA_IS_XDP_INDEX(adapter, i) &&
-				adapter->ena_napi[i].xdp_ring);
+		netif_napi_del(&adapter->ena_napi[i].napi);
+
+		WARN_ON(!ENA_IS_XDP_INDEX(adapter, i) &&
+			adapter->ena_napi[i].xdp_ring);
 	}
 }
 
-- 
2.28.0