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authorDexuan Cui <decui@microsoft.com>2018-08-02 03:08:23 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-08-02 10:20:59 +0200
commitd3b26dd7cb0e3433bfd3c1d4dcf74c6039bb49fb (patch)
treed6793900dfa4d886d23c1c33c37e9148bd0e12d2 /drivers/hv
parent7026a5fd7f2cd36fee5ec40f3652f942700671b7 (diff)
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Drivers: hv: vmbus: Reset the channel callback in vmbus_onoffer_rescind()
Before setting channel->rescind in vmbus_rescind_cleanup(), we should make sure the channel callback won't run any more, otherwise a high-level driver like pci_hyperv, which may be infinitely waiting for the host VSP's response and notices the channel has been rescinded, can't safely give up: e.g., in hv_pci_protocol_negotiation() -> wait_for_response(), it's unsafe to exit from wait_for_response() and proceed with the on-stack variable "comp_pkt" popped. The issue was originally spotted by Michael Kelley <mikelley@microsoft.com>. In vmbus_close_internal(), the patch also minimizes the range protected by disabling/enabling channel->callback_event: we don't really need that for the whole function. Signed-off-by: Dexuan Cui <decui@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Cc: stable@vger.kernel.org Cc: K. Y. Srinivasan <kys@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Michael Kelley <mikelley@microsoft.com> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv')
-rw-r--r--drivers/hv/channel.c40
-rw-r--r--drivers/hv/channel_mgmt.c6
2 files changed, 30 insertions, 16 deletions
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index ba0a092ae085..c3949220b770 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -558,11 +558,8 @@ static void reset_channel_cb(void *arg)
channel->onchannel_callback = NULL;
}
-static int vmbus_close_internal(struct vmbus_channel *channel)
+void vmbus_reset_channel_cb(struct vmbus_channel *channel)
{
- struct vmbus_channel_close_channel *msg;
- int ret;
-
/*
* vmbus_on_event(), running in the per-channel tasklet, can race
* with vmbus_close_internal() in the case of SMP guest, e.g., when
@@ -572,6 +569,29 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
*/
tasklet_disable(&channel->callback_event);
+ channel->sc_creation_callback = NULL;
+
+ /* Stop the callback asap */
+ if (channel->target_cpu != get_cpu()) {
+ put_cpu();
+ smp_call_function_single(channel->target_cpu, reset_channel_cb,
+ channel, true);
+ } else {
+ reset_channel_cb(channel);
+ put_cpu();
+ }
+
+ /* Re-enable tasklet for use on re-open */
+ tasklet_enable(&channel->callback_event);
+}
+
+static int vmbus_close_internal(struct vmbus_channel *channel)
+{
+ struct vmbus_channel_close_channel *msg;
+ int ret;
+
+ vmbus_reset_channel_cb(channel);
+
/*
* In case a device driver's probe() fails (e.g.,
* util_probe() -> vmbus_open() returns -ENOMEM) and the device is
@@ -585,16 +605,6 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
}
channel->state = CHANNEL_OPEN_STATE;
- channel->sc_creation_callback = NULL;
- /* Stop callback and cancel the timer asap */
- if (channel->target_cpu != get_cpu()) {
- put_cpu();
- smp_call_function_single(channel->target_cpu, reset_channel_cb,
- channel, true);
- } else {
- reset_channel_cb(channel);
- put_cpu();
- }
/* Send a closing message */
@@ -639,8 +649,6 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
get_order(channel->ringbuffer_pagecount * PAGE_SIZE));
out:
- /* re-enable tasklet for use on re-open */
- tasklet_enable(&channel->callback_event);
return ret;
}
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index f3b551a50653..0f0e091c117c 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -893,6 +893,12 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
}
/*
+ * Before setting channel->rescind in vmbus_rescind_cleanup(), we
+ * should make sure the channel callback is not running any more.
+ */
+ vmbus_reset_channel_cb(channel);
+
+ /*
* Now wait for offer handling to complete.
*/
vmbus_rescind_cleanup(channel);