From b307b38962eb0f22d1aa6dcf53cb7d3c2ed5eec7 Mon Sep 17 00:00:00 2001 From: Dexuan Cui Date: Thu, 5 Sep 2019 23:01:21 +0000 Subject: [PATCH] Drivers: hv: vmbus: Suspend after cleaning up hv_sock and sub channels Before suspend, Linux must make sure all the hv_sock channels have been properly cleaned up, because a hv_sock connection can not persist across hibernation, and the user-space app must be properly notified of the state change of the connection. Before suspend, Linux also must make sure all the sub-channels have been destroyed, i.e. the related channel structs of the sub-channels must be properly removed, otherwise they would cause a conflict when the sub-channels are recreated upon resume. Add a counter to track such channels, and vmbus_bus_suspend() should wait for the counter to drop to zero. Signed-off-by: Dexuan Cui Reviewed-by: Michael Kelley Signed-off-by: Sasha Levin --- drivers/hv/channel_mgmt.c | 26 +++++++++++++++++++++++ drivers/hv/connection.c | 3 +++ drivers/hv/hyperv_vmbus.h | 12 +++++++++++ drivers/hv/vmbus_drv.c | 44 ++++++++++++++++++++++++++++++++++++++- 4 files changed, 84 insertions(+), 1 deletion(-) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 44b92fa1b7fa..5518d031f62a 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -545,6 +545,10 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel) mutex_lock(&vmbus_connection.channel_mutex); + /* Remember the channels that should be cleaned up upon suspend. */ + if (is_hvsock_channel(newchannel) || is_sub_channel(newchannel)) + atomic_inc(&vmbus_connection.nr_chan_close_on_suspend); + /* * Now that we have acquired the channel_mutex, * we can release the potentially racing rescind thread. @@ -944,6 +948,16 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr) vmbus_process_offer(newchannel); } +static void check_ready_for_suspend_event(void) +{ + /* + * If all the sub-channels or hv_sock channels have been cleaned up, + * then it's safe to suspend. + */ + if (atomic_dec_and_test(&vmbus_connection.nr_chan_close_on_suspend)) + complete(&vmbus_connection.ready_for_suspend_event); +} + /* * vmbus_onoffer_rescind - Rescind offer handler. * @@ -954,6 +968,7 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) struct vmbus_channel_rescind_offer *rescind; struct vmbus_channel *channel; struct device *dev; + bool clean_up_chan_for_suspend; rescind = (struct vmbus_channel_rescind_offer *)hdr; @@ -993,6 +1008,8 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) return; } + clean_up_chan_for_suspend = is_hvsock_channel(channel) || + is_sub_channel(channel); /* * Before setting channel->rescind in vmbus_rescind_cleanup(), we * should make sure the channel callback is not running any more. @@ -1018,6 +1035,10 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) if (channel->device_obj) { if (channel->chn_rescind_callback) { channel->chn_rescind_callback(channel); + + if (clean_up_chan_for_suspend) + check_ready_for_suspend_event(); + return; } /* @@ -1050,6 +1071,11 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) } mutex_unlock(&vmbus_connection.channel_mutex); } + + /* The "channel" may have been freed. Do not access it any longer. */ + + if (clean_up_chan_for_suspend) + check_ready_for_suspend_event(); } void vmbus_hvsock_device_unregister(struct vmbus_channel *channel) diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c index 806319cd5ccf..99851ea682eb 100644 --- a/drivers/hv/connection.c +++ b/drivers/hv/connection.c @@ -26,6 +26,9 @@ struct vmbus_connection vmbus_connection = { .conn_state = DISCONNECTED, .next_gpadl_handle = ATOMIC_INIT(0xE1E10), + + .ready_for_suspend_event= COMPLETION_INITIALIZER( + vmbus_connection.ready_for_suspend_event), }; EXPORT_SYMBOL_GPL(vmbus_connection); diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h index e657197a027a..974b747ca1fc 100644 --- a/drivers/hv/hyperv_vmbus.h +++ b/drivers/hv/hyperv_vmbus.h @@ -260,6 +260,18 @@ struct vmbus_connection { struct workqueue_struct *work_queue; struct workqueue_struct *handle_primary_chan_wq; struct workqueue_struct *handle_sub_chan_wq; + + /* + * The number of sub-channels and hv_sock channels that should be + * cleaned up upon suspend: sub-channels will be re-created upon + * resume, and hv_sock channels should not survive suspend. + */ + atomic_t nr_chan_close_on_suspend; + /* + * vmbus_bus_suspend() waits for "nr_chan_close_on_suspend" to + * drop to zero. + */ + struct completion ready_for_suspend_event; }; diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 45b976ec6e79..32ec951d334f 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -2127,7 +2127,8 @@ acpi_walk_err: static int vmbus_bus_suspend(struct device *dev) { - struct vmbus_channel *channel; + struct vmbus_channel *channel, *sc; + unsigned long flags; while (atomic_read(&vmbus_connection.offer_in_progress) != 0) { /* @@ -2146,6 +2147,44 @@ static int vmbus_bus_suspend(struct device *dev) } mutex_unlock(&vmbus_connection.channel_mutex); + /* + * Wait until all the sub-channels and hv_sock channels have been + * cleaned up. Sub-channels should be destroyed upon suspend, otherwise + * they would conflict with the new sub-channels that will be created + * in the resume path. hv_sock channels should also be destroyed, but + * a hv_sock channel of an established hv_sock connection can not be + * really destroyed since it may still be referenced by the userspace + * application, so we just force the hv_sock channel to be rescinded + * by vmbus_force_channel_rescinded(), and the userspace application + * will thoroughly destroy the channel after hibernation. + * + * Note: the counter nr_chan_close_on_suspend may never go above 0 if + * the VM has no sub-channel and hv_sock channel, e.g. a 1-vCPU VM. + */ + if (atomic_read(&vmbus_connection.nr_chan_close_on_suspend) > 0) + wait_for_completion(&vmbus_connection.ready_for_suspend_event); + + mutex_lock(&vmbus_connection.channel_mutex); + + list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) { + if (is_hvsock_channel(channel)) { + if (!channel->rescind) { + pr_err("hv_sock channel not rescinded!\n"); + WARN_ON_ONCE(1); + } + continue; + } + + spin_lock_irqsave(&channel->lock, flags); + list_for_each_entry(sc, &channel->sc_list, sc_list) { + pr_err("Sub-channel not deleted!\n"); + WARN_ON_ONCE(1); + } + spin_unlock_irqrestore(&channel->lock, flags); + } + + mutex_unlock(&vmbus_connection.channel_mutex); + vmbus_initiate_unload(false); vmbus_connection.conn_state = DISCONNECTED; @@ -2186,6 +2225,9 @@ static int vmbus_bus_resume(struct device *dev) vmbus_request_offers(); + /* Reset the event for the next suspend. */ + reinit_completion(&vmbus_connection.ready_for_suspend_event); + return 0; }