From: Jakub Kicinski <kuba@kernel.org>
To: Yunsheng Lin <linyunsheng@huawei.com>
Cc: <davem@davemloft.net>, <linmiaohe@huawei.com>,
<martin.varghese@nokia.com>, <pabeni@redhat.com>,
<pshelar@ovn.org>, <fw@strlen.de>, <gnault@redhat.com>,
<steffen.klassert@secunet.com>, <kyk.segfault@gmail.com>,
<viro@zeniv.linux.org.uk>, <vladimir.oltean@nxp.com>,
<edumazet@google.com>, <saeed@kernel.org>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linuxarm@huawei.com>
Subject: Re: [PATCH net-next] net: add in_softirq() debug checking in napi_consume_skb()
Date: Sat, 31 Oct 2020 15:38:24 -0700 [thread overview]
Message-ID: <20201031153824.7ae83b90@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net> (raw)
In-Reply-To: <1603971288-4786-1-git-send-email-linyunsheng@huawei.com>
On Thu, 29 Oct 2020 19:34:48 +0800 Yunsheng Lin wrote:
> The current semantic for napi_consume_skb() is that caller need
> to provide non-zero budget when calling from NAPI context, and
> breaking this semantic will cause hard to debug problem, because
> _kfree_skb_defer() need to run in atomic context in order to push
> the skb to the particular cpu' napi_alloc_cache atomically.
>
> So add a in_softirq() debug checking in napi_consume_skb() to catch
> this kind of error.
>
> Suggested-by: Eric Dumazet <edumazet@google.com>
> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 1ba8f01..1834007 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -897,6 +897,10 @@ void napi_consume_skb(struct sk_buff *skb, int budget)
> return;
> }
>
> + DEBUG_NET_WARN(!in_softirq(),
> + "%s is called with non-zero budget outside softirq context.\n",
> + __func__);
Can't we use lockdep instead of defining our own knobs?
Like this maybe?
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index f5594879175a..5253a167d00c 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -594,6 +594,14 @@ do { \
this_cpu_read(hardirqs_enabled))); \
} while (0)
+#define lockdep_assert_in_softirq() \
+do { \
+ WARN_ON_ONCE(__lockdep_enabled && \
+ (softirq_count() == 0 || \
+ this_cpu_read(hardirq_context))); \
+} while (0)
> if (!skb_unref(skb))
> return;
>
next prev parent reply other threads:[~2020-10-31 22:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-29 11:34 [PATCH net-next] net: add in_softirq() debug checking in napi_consume_skb() Yunsheng Lin
2020-10-31 22:38 ` Jakub Kicinski [this message]
2020-11-02 3:14 ` Yunsheng Lin
2020-11-02 19:41 ` Jakub Kicinski
2020-11-18 1:57 ` Yunsheng Lin
2020-11-18 15:43 ` Jakub Kicinski
2020-11-18 15:57 ` Peter Zijlstra
2020-11-18 16:26 ` Jakub Kicinski
2020-11-19 9:19 ` Yunsheng Lin
2020-11-19 11:41 ` Peter Zijlstra
2020-11-19 12:29 ` Yunsheng Lin
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