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authorOlaf Hering <ohering@suse.de>2019-04-23 17:00:05 +0200
committerOlaf Hering <ohering@suse.de>2019-04-23 17:00:05 +0200
commitc85428939ba71618154cfe5b6bd2c6655dd050ed (patch)
treec357de904893d97cd3cc053278d81a2d33975af5
parent2171c842fed7af434e5719a70da7d4b118bbd597 (diff)
- Drivers: hv: vmbus: Offload the handling of channels to twoSLE15-AZURE
workqueues (bsc#1130567). suse-commit: 03400072cf66a1543ca51a38630bb536ba3e00ef
-rw-r--r--drivers/hv/channel_mgmt.c188
-rw-r--r--drivers/hv/connection.c24
-rw-r--r--drivers/hv/hyperv_vmbus.h7
-rw-r--r--include/linux/hyperv.h7
4 files changed, 161 insertions, 65 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 847c463129f3..e90f7801c9b4 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -439,60 +439,16 @@ void vmbus_free_channels(void)
}
}
-/*
- * vmbus_process_offer - Process the offer by creating a channel/device
- * associated with this offer
- */
-static void vmbus_process_offer(struct vmbus_channel *newchannel)
+/* Note: the function can run concurrently for primary/sub channels. */
+static void vmbus_add_channel_work(struct work_struct *work)
{
- struct vmbus_channel *channel;
- bool fnew = true;
+ struct vmbus_channel *newchannel =
+ container_of(work, struct vmbus_channel, add_channel_work);
+ struct vmbus_channel *primary_channel = newchannel->primary_channel;
unsigned long flags;
u16 dev_type;
int ret;
- /* Make sure this is a new offer */
- mutex_lock(&vmbus_connection.channel_mutex);
-
- /*
- * Now that we have acquired the channel_mutex,
- * we can release the potentially racing rescind thread.
- */
- atomic_dec(&vmbus_connection.offer_in_progress);
-
- list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
- if (!uuid_le_cmp(channel->offermsg.offer.if_type,
- newchannel->offermsg.offer.if_type) &&
- !uuid_le_cmp(channel->offermsg.offer.if_instance,
- newchannel->offermsg.offer.if_instance)) {
- fnew = false;
- break;
- }
- }
-
- if (fnew)
- list_add_tail(&newchannel->listentry,
- &vmbus_connection.chn_list);
-
- mutex_unlock(&vmbus_connection.channel_mutex);
-
- if (!fnew) {
- /*
- * Check to see if this is a sub-channel.
- */
- if (newchannel->offermsg.offer.sub_channel_index != 0) {
- /*
- * Process the sub-channel.
- */
- newchannel->primary_channel = channel;
- spin_lock_irqsave(&channel->lock, flags);
- list_add_tail(&newchannel->sc_list, &channel->sc_list);
- spin_unlock_irqrestore(&channel->lock, flags);
- } else {
- goto err_free_chan;
- }
- }
-
dev_type = hv_get_dev_type(newchannel);
init_vp_index(newchannel, dev_type);
@@ -510,27 +466,26 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
/*
* This state is used to indicate a successful open
* so that when we do close the channel normally, we
- * can cleanup properly
+ * can cleanup properly.
*/
newchannel->state = CHANNEL_OPEN_STATE;
- if (!fnew) {
- struct hv_device *dev
- = newchannel->primary_channel->device_obj;
+ if (primary_channel != NULL) {
+ /* newchannel is a sub-channel. */
+ struct hv_device *dev = primary_channel->device_obj;
if (vmbus_add_channel_kobj(dev, newchannel))
- goto err_free_chan;
+ goto err_deq_chan;
+
+ if (primary_channel->sc_creation_callback != NULL)
+ primary_channel->sc_creation_callback(newchannel);
- if (channel->sc_creation_callback != NULL)
- channel->sc_creation_callback(newchannel);
newchannel->probe_done = true;
return;
}
/*
- * Start the process of binding this offer to the driver
- * We need to set the DeviceObject field before calling
- * vmbus_child_dev_add()
+ * Start the process of binding the primary channel to the driver
*/
newchannel->device_obj = vmbus_device_create(
&newchannel->offermsg.offer.if_type,
@@ -559,13 +514,28 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
err_deq_chan:
mutex_lock(&vmbus_connection.channel_mutex);
- list_del(&newchannel->listentry);
+
+ /*
+ * We need to set the flag, otherwise
+ * vmbus_onoffer_rescind() can be blocked.
+ */
+ newchannel->probe_done = true;
+
+ if (primary_channel == NULL) {
+ list_del(&newchannel->listentry);
+ } else {
+ spin_lock_irqsave(&primary_channel->lock, flags);
+ list_del(&newchannel->sc_list);
+ spin_unlock_irqrestore(&primary_channel->lock, flags);
+ }
+
mutex_unlock(&vmbus_connection.channel_mutex);
if (newchannel->target_cpu != get_cpu()) {
put_cpu();
smp_call_function_single(newchannel->target_cpu,
- percpu_channel_deq, newchannel, true);
+ percpu_channel_deq,
+ newchannel, true);
} else {
percpu_channel_deq(newchannel);
put_cpu();
@@ -573,14 +543,104 @@ err_deq_chan:
vmbus_release_relid(newchannel->offermsg.child_relid);
-err_free_chan:
free_channel(newchannel);
}
/*
+ * vmbus_process_offer - Process the offer by creating a channel/device
+ * associated with this offer
+ */
+static void vmbus_process_offer(struct vmbus_channel *newchannel)
+{
+ struct vmbus_channel *channel;
+ struct workqueue_struct *wq;
+ unsigned long flags;
+ bool fnew = true;
+
+ mutex_lock(&vmbus_connection.channel_mutex);
+
+ /*
+ * Now that we have acquired the channel_mutex,
+ * we can release the potentially racing rescind thread.
+ */
+ atomic_dec(&vmbus_connection.offer_in_progress);
+
+ list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+ if (!uuid_le_cmp(channel->offermsg.offer.if_type,
+ newchannel->offermsg.offer.if_type) &&
+ !uuid_le_cmp(channel->offermsg.offer.if_instance,
+ newchannel->offermsg.offer.if_instance)) {
+ fnew = false;
+ break;
+ }
+ }
+
+ if (fnew)
+ list_add_tail(&newchannel->listentry,
+ &vmbus_connection.chn_list);
+ else {
+ /*
+ * Check to see if this is a valid sub-channel.
+ */
+ if (newchannel->offermsg.offer.sub_channel_index == 0) {
+ mutex_unlock(&vmbus_connection.channel_mutex);
+ /*
+ * Don't call free_channel(), because newchannel->kobj
+ * is not initialized yet.
+ */
+ kfree(newchannel);
+ WARN_ON_ONCE(1);
+ return;
+ }
+ /*
+ * Process the sub-channel.
+ */
+ newchannel->primary_channel = channel;
+ spin_lock_irqsave(&channel->lock, flags);
+ list_add_tail(&newchannel->sc_list, &channel->sc_list);
+ spin_unlock_irqrestore(&channel->lock, flags);
+ }
+
+ mutex_unlock(&vmbus_connection.channel_mutex);
+
+ /*
+ * vmbus_process_offer() mustn't call channel->sc_creation_callback()
+ * directly for sub-channels, because sc_creation_callback() ->
+ * vmbus_open() may never get the host's response to the
+ * OPEN_CHANNEL message (the host may rescind a channel at any time,
+ * e.g. in the case of hot removing a NIC), and vmbus_onoffer_rescind()
+ * may not wake up the vmbus_open() as it's blocked due to a non-zero
+ * vmbus_connection.offer_in_progress, and finally we have a deadlock.
+ *
+ * The above is also true for primary channels, if the related device
+ * drivers use sync probing mode by default.
+ *
+ * And, usually the handling of primary channels and sub-channels can
+ * depend on each other, so we should offload them to different
+ * workqueues to avoid possible deadlock, e.g. in sync-probing mode,
+ * NIC1's netvsc_subchan_work() can race with NIC2's netvsc_probe() ->
+ * rtnl_lock(), and causes deadlock: the former gets the rtnl_lock
+ * and waits for all the sub-channels to appear, but the latter
+ * can't get the rtnl_lock and this blocks the handling of
+ * sub-channels.
+ */
+ INIT_WORK(&newchannel->add_channel_work, vmbus_add_channel_work);
+ wq = fnew ? vmbus_connection.handle_primary_chan_wq :
+ vmbus_connection.handle_sub_chan_wq;
+ queue_work(wq, &newchannel->add_channel_work);
+}
+
+/*
* We use this state to statically distribute the channel interrupt load.
*/
static int next_numa_node_id;
+/*
+ * init_vp_index() accesses global variables like next_numa_node_id, and
+ * it can run concurrently for primary channels and sub-channels: see
+ * vmbus_process_offer(), so we need the lock to protect the global
+ * variables.
+ */
+static DEFINE_SPINLOCK(bind_channel_to_cpu_lock);
/*
* Starting with Win8, we can statically distribute the incoming
@@ -614,6 +674,8 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
return;
}
+ spin_lock(&bind_channel_to_cpu_lock);
+
/*
* Based on the channel affinity policy, we will assign the NUMA
* nodes.
@@ -695,6 +757,8 @@ static void init_vp_index(struct vmbus_channel *channel, u16 dev_type)
channel->target_cpu = cur_cpu;
channel->target_vp = hv_cpu_number_to_vp_number(cur_cpu);
+
+ spin_unlock(&bind_channel_to_cpu_lock);
}
static void vmbus_wait_for_unload(void)
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index f4d08c8ac7f8..4fe117b761ce 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -190,6 +190,20 @@ int vmbus_connect(void)
goto cleanup;
}
+ vmbus_connection.handle_primary_chan_wq =
+ create_workqueue("hv_pri_chan");
+ if (!vmbus_connection.handle_primary_chan_wq) {
+ ret = -ENOMEM;
+ goto cleanup;
+ }
+
+ vmbus_connection.handle_sub_chan_wq =
+ create_workqueue("hv_sub_chan");
+ if (!vmbus_connection.handle_sub_chan_wq) {
+ ret = -ENOMEM;
+ goto cleanup;
+ }
+
INIT_LIST_HEAD(&vmbus_connection.chn_msg_list);
spin_lock_init(&vmbus_connection.channelmsg_lock);
@@ -280,10 +294,14 @@ void vmbus_disconnect(void)
*/
vmbus_initiate_unload(false);
- if (vmbus_connection.work_queue) {
- drain_workqueue(vmbus_connection.work_queue);
+ if (vmbus_connection.handle_sub_chan_wq)
+ destroy_workqueue(vmbus_connection.handle_sub_chan_wq);
+
+ if (vmbus_connection.handle_primary_chan_wq)
+ destroy_workqueue(vmbus_connection.handle_primary_chan_wq);
+
+ if (vmbus_connection.work_queue)
destroy_workqueue(vmbus_connection.work_queue);
- }
if (vmbus_connection.int_page) {
free_pages((unsigned long)vmbus_connection.int_page, 0);
diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index dc7ad4b50481..6bf632e4a8f0 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -336,7 +336,14 @@ struct vmbus_connection {
struct list_head chn_list;
struct mutex channel_mutex;
+ /*
+ * An offer message is handled first on the work_queue, and then
+ * is further handled on handle_primary_chan_wq or
+ * handle_sub_chan_wq.
+ */
struct workqueue_struct *work_queue;
+ struct workqueue_struct *handle_primary_chan_wq;
+ struct workqueue_struct *handle_sub_chan_wq;
};
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 3e70c4bb812c..56daea5005c4 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -896,6 +896,13 @@ struct vmbus_channel {
bool probe_done;
+ /*
+ * We must offload the handling of the primary/sub channels
+ * from the single-threaded vmbus_connection.work_queue to
+ * two different workqueue, otherwise we can block
+ * vmbus_connection.work_queue and hang: see vmbus_process_offer().
+ */
+ struct work_struct add_channel_work;
};
static inline bool is_hvsock_channel(const struct vmbus_channel *c)