All of lore.kernel.org
 help / color / mirror / Atom feed
From: David Miller <davem@davemloft.net>
To: andrea.righi@canonical.com
Cc: boris.ostrovsky@oracle.com, jgross@suse.com,
	sstabellini@kernel.org, kuba@kernel.org,
	xen-devel@lists.xenproject.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] xen-netfront: fix potential deadlock in xennet_remove()
Date: Fri, 24 Jul 2020 17:02:20 -0700 (PDT)	[thread overview]
Message-ID: <20200724.170220.1275270219725381485.davem@davemloft.net> (raw)
In-Reply-To: <20200724085910.GA1043801@xps-13>

From: Andrea Righi <andrea.righi@canonical.com>
Date: Fri, 24 Jul 2020 10:59:10 +0200

> There's a potential race in xennet_remove(); this is what the driver is
> doing upon unregistering a network device:
> 
>   1. state = read bus state
>   2. if state is not "Closed":
>   3.    request to set state to "Closing"
>   4.    wait for state to be set to "Closing"
>   5.    request to set state to "Closed"
>   6.    wait for state to be set to "Closed"
> 
> If the state changes to "Closed" immediately after step 1 we are stuck
> forever in step 4, because the state will never go back from "Closed" to
> "Closing".
> 
> Make sure to check also for state == "Closed" in step 4 to prevent the
> deadlock.
> 
> Also add a 5 sec timeout any time we wait for the bus state to change,
> to avoid getting stuck forever in wait_event().
> 
> Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
> ---
> Changes in v2:
>  - remove all dev_dbg() calls (as suggested by David Miller)

Applied, thank you.

WARNING: multiple messages have this Message-ID (diff)
From: David Miller <davem@davemloft.net>
To: andrea.righi@canonical.com
Cc: jgross@suse.com, sstabellini@kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
	kuba@kernel.org, boris.ostrovsky@oracle.com
Subject: Re: [PATCH v2] xen-netfront: fix potential deadlock in xennet_remove()
Date: Fri, 24 Jul 2020 17:02:20 -0700 (PDT)	[thread overview]
Message-ID: <20200724.170220.1275270219725381485.davem@davemloft.net> (raw)
In-Reply-To: <20200724085910.GA1043801@xps-13>

From: Andrea Righi <andrea.righi@canonical.com>
Date: Fri, 24 Jul 2020 10:59:10 +0200

> There's a potential race in xennet_remove(); this is what the driver is
> doing upon unregistering a network device:
> 
>   1. state = read bus state
>   2. if state is not "Closed":
>   3.    request to set state to "Closing"
>   4.    wait for state to be set to "Closing"
>   5.    request to set state to "Closed"
>   6.    wait for state to be set to "Closed"
> 
> If the state changes to "Closed" immediately after step 1 we are stuck
> forever in step 4, because the state will never go back from "Closed" to
> "Closing".
> 
> Make sure to check also for state == "Closed" in step 4 to prevent the
> deadlock.
> 
> Also add a 5 sec timeout any time we wait for the bus state to change,
> to avoid getting stuck forever in wait_event().
> 
> Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
> ---
> Changes in v2:
>  - remove all dev_dbg() calls (as suggested by David Miller)

Applied, thank you.


  reply	other threads:[~2020-07-25  0:02 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-24  8:59 [PATCH v2] xen-netfront: fix potential deadlock in xennet_remove() Andrea Righi
2020-07-24  8:59 ` Andrea Righi
2020-07-25  0:02 ` David Miller [this message]
2020-07-25  0:02   ` David Miller

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200724.170220.1275270219725381485.davem@davemloft.net \
    --to=davem@davemloft.net \
    --cc=andrea.righi@canonical.com \
    --cc=boris.ostrovsky@oracle.com \
    --cc=jgross@suse.com \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=sstabellini@kernel.org \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.