From: Jeff Garzik <jgarzik@pobox.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Francois Romieu <romieu@fr.zoreil.com>,
mingo@elte.hu, jgarzik@redhat.com, linux-kernel@vger.kernel.org,
akpm@osdl.org, davem@redhat.com
Subject: Re: [lock validator] drivers/net/8139too.c: deadlock?
Date: Thu, 26 Jan 2006 21:44:37 -0500 [thread overview]
Message-ID: <43D98915.6040004@pobox.com> (raw)
In-Reply-To: <E1F2JFb-0007MW-00@gondolin.me.apana.org.au>
Herbert Xu wrote:
> You've got it.
>
> rx_poll => rtl8139_rx => netif_receive_skb => ... => tcp_v4_rcv
>
> In fact once we're at netif_receive_skb it's easy to see how we'll grab
> xmit_lock again.
>
> Prescription: Move TX timeout handling into a work queue.
This was my recommendation as well.
Using a work queue not only solves this locking problem, but it also
enables the possibility of sleeping, a common operation during the
hardware resets that often occur during ->tx_timeout()
Anyone who wants to make this change in a driver, don't forget that this
could race with other operations, notably dev->stop() or suspend.
Jeff
next prev parent reply other threads:[~2006-01-27 2:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-26 22:43 [lock validator] drivers/net/8139too.c: deadlock? Ingo Molnar
2006-01-27 0:35 ` Francois Romieu
2006-01-27 2:22 ` Herbert Xu
2006-01-27 2:44 ` Jeff Garzik [this message]
2006-01-31 0:24 ` [PATCH] 8139too: fix a TX timeout watchdog thread against NAPI softirq race Francois Romieu
2006-01-31 18:49 ` Ingo Molnar
2006-01-31 18:57 ` Ingo Molnar
2006-02-01 0:55 ` Andrew Morton
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