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Drivers: hv: vmbus: fix the race when querying & updating the percpu list

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There is a rare race when we remove an entry from the global list
hv_context.percpu_list[cpu] in hv_process_channel_removal() ->
percpu_channel_deq() -> list_del(): at this time, if vmbus_on_event() ->
process_chn_event() -> pcpu_relid2channel() is trying to query the list,
we can get the kernel fault.

Similarly, we also have the issue in the code path: vmbus_process_offer() ->
percpu_channel_enq().

We can resolve the issue by disabling the tasklet when updating the list.

The patch also moves vmbus_release_relid() to a later place where
the channel has been removed from the per-cpu and the global lists.

Reported-by: Rolf Neugebauer <rolf.neugebauer@docker.com>
Signed-off-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dexuan Cui 2016-06-09 18:47:24 -07:00 • committed by Greg Kroah-Hartman
parent e0fa3e5e7d
commit 638fea33ae
3 changed files with 33 additions and 8 deletions
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3
include/linux/hyperv.h
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@ -1357,6 +1357,9 @@ extern bool vmbus_prep_negotiate_resp(struct icmsg_hdr *,
struct icmsg_negotiate *, u8 *, int,
int);
void hv_event_tasklet_disable(struct vmbus_channel *channel);
void hv_event_tasklet_enable(struct vmbus_channel *channel);
void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid);
/*