netdev - [PATCH net] net: sched: check netif_xmit_frozen_or_stopped() in sch_direct

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Message-ID: <20180525181144.224395-1-songliubraving@fb.com>
Date:   Fri, 25 May 2018 11:11:44 -0700
From:   Song Liu <songliubraving@...com>
To:     <netdev@...r.kernel.org>
CC:     Song Liu <songliubraving@...com>, <kernel-team@...com>,
        John Fastabend <john.fastabend@...il.com>,
        "David S . Miller" <davem@...emloft.net>
Subject: [PATCH net] net: sched: check netif_xmit_frozen_or_stopped() in sch_direct_xmit()

Summary:

At the end of sch_direct_xmit(), we are in the else path of
!dev_xmit_complete(ret), which means ret == NETDEV_TX_OK. The following
condition will always fail and netif_xmit_frozen_or_stopped() is not
checked at all.

    if (ret && netif_xmit_frozen_or_stopped(txq))
         return false;

In this patch, this condition is fixed as:

    if (netif_xmit_frozen_or_stopped(txq))
         return false;

and further simplifies the code as:

    return !netif_xmit_frozen_or_stopped(txq);

Fixes: 29b86cdac00a ("net: sched: remove remaining uses for qdisc_qlen in xmit path")
Cc: John Fastabend <john.fastabend@...il.com>
Cc: David S. Miller <davem@...emloft.net>
Signed-off-by: Song Liu <songliubraving@...com>
---
 net/sched/sch_generic.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 39c144b..8261d48 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -346,10 +346,7 @@ bool sch_direct_xmit(struct sk_buff *skb, struct Qdisc *q,
 		return false;
 	}
 
-	if (ret && netif_xmit_frozen_or_stopped(txq))
-		return false;
-
-	return true;
+	return !netif_xmit_frozen_or_stopped(txq);
 }
 
 /*
-- 
2.9.5