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Date: Fri, 24 Jul 2020 17:02:20 -0700 (PDT) From: David Miller <davem@...emloft.net> To: andrea.righi@...onical.com Cc: boris.ostrovsky@...cle.com, jgross@...e.com, sstabellini@...nel.org, kuba@...nel.org, xen-devel@...ts.xenproject.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2] xen-netfront: fix potential deadlock in xennet_remove() From: Andrea Righi <andrea.righi@...onical.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@...onical.com> > --- > Changes in v2: > - remove all dev_dbg() calls (as suggested by David Miller) Applied, thank you.
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