4.14-stable review patch. If anyone has any objections, please let me know.
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From: K. Y. Srinivasan kys@microsoft.com
commit 7fa32e5ec28b1609abc0b797b58267f725fc3964 upstream.
The current rescind processing code will not correctly handle the case where the host immediately rescinds a channel that has been offerred. In this case, we could be blocked in the open call and since the channel is rescinded, the host will not respond and we could be blocked forever in the vmbus open call.i Fix this problem.
Signed-off-by: K. Y. Srinivasan kys@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/hv/channel.c | 10 ++++++++-- drivers/hv/channel_mgmt.c | 7 ++++--- include/linux/hyperv.h | 1 + 3 files changed, 13 insertions(+), 5 deletions(-)
--- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -640,22 +640,28 @@ void vmbus_close(struct vmbus_channel *c */ return; } - mutex_lock(&vmbus_connection.channel_mutex); /* * Close all the sub-channels first and then close the * primary channel. */ list_for_each_safe(cur, tmp, &channel->sc_list) { cur_channel = list_entry(cur, struct vmbus_channel, sc_list); - vmbus_close_internal(cur_channel); if (cur_channel->rescind) { + wait_for_completion(&cur_channel->rescind_event); + mutex_lock(&vmbus_connection.channel_mutex); + vmbus_close_internal(cur_channel); hv_process_channel_removal( cur_channel->offermsg.child_relid); + } else { + mutex_lock(&vmbus_connection.channel_mutex); + vmbus_close_internal(cur_channel); } + mutex_unlock(&vmbus_connection.channel_mutex); } /* * Now close the primary. */ + mutex_lock(&vmbus_connection.channel_mutex); vmbus_close_internal(channel); mutex_unlock(&vmbus_connection.channel_mutex); } --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -333,6 +333,7 @@ static struct vmbus_channel *alloc_chann return NULL;
spin_lock_init(&channel->lock); + init_completion(&channel->rescind_event);
INIT_LIST_HEAD(&channel->sc_list); INIT_LIST_HEAD(&channel->percpu_list); @@ -883,6 +884,7 @@ static void vmbus_onoffer_rescind(struct /* * Now wait for offer handling to complete. */ + vmbus_rescind_cleanup(channel); while (READ_ONCE(channel->probe_done) == false) { /* * We wait here until any channel offer is currently @@ -898,7 +900,6 @@ static void vmbus_onoffer_rescind(struct if (channel->device_obj) { if (channel->chn_rescind_callback) { channel->chn_rescind_callback(channel); - vmbus_rescind_cleanup(channel); return; } /* @@ -907,7 +908,6 @@ static void vmbus_onoffer_rescind(struct */ dev = get_device(&channel->device_obj->device); if (dev) { - vmbus_rescind_cleanup(channel); vmbus_device_unregister(channel->device_obj); put_device(dev); } @@ -921,13 +921,14 @@ static void vmbus_onoffer_rescind(struct * 2. Then close the primary channel. */ mutex_lock(&vmbus_connection.channel_mutex); - vmbus_rescind_cleanup(channel); if (channel->state == CHANNEL_OPEN_STATE) { /* * The channel is currently not open; * it is safe for us to cleanup the channel. */ hv_process_channel_removal(rescind->child_relid); + } else { + complete(&channel->rescind_event); } mutex_unlock(&vmbus_connection.channel_mutex); } --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -708,6 +708,7 @@ struct vmbus_channel { u8 monitor_bit;
bool rescind; /* got rescind msg */ + struct completion rescind_event;
u32 ringbuffer_gpadlhandle;