From 652594c7dfd9bf6392e3a727bc69d89a2562d953 Mon Sep 17 00:00:00 2001 From: Dexuan Cui Date: Fri, 27 Mar 2015 09:10:08 -0700 Subject: [PATCH] hv: run non-blocking message handlers in the dispatch tasklet A work item in vmbus_connection.work_queue can sleep, waiting for a new host message (usually it is some kind of "completion" message). Currently the new message will be handled in the same workqueue, but since work items in the workqueue is serialized, we actually have no chance to handle the new message if the current work item is sleeping -- as as result, the current work item will hang forever. K. Y. has posted the below fix to resolve the issue: Drivers: hv: vmbus: Perform device register in the per-channel work element Actually we can simplify the fix by directly running non-blocking message handlers in the dispatch tasklet (inspired by K. Y.). This patch is the fundamental change. The following 2 patches will simplify the message offering and rescind-offering handling a lot. Signed-off-by: Dexuan Cui Cc: K. Y. Srinivasan Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/channel_mgmt.c | 41 +++++++++++++++++---------------------- drivers/hv/hyperv_vmbus.h | 17 ++++++++++++++++ drivers/hv/vmbus_drv.c | 21 +++++++++++++++++--- 3 files changed, 53 insertions(+), 26 deletions(-) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index bb39705a89d9..287f07b1bef6 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -33,11 +33,6 @@ #include "hyperv_vmbus.h" -struct vmbus_channel_message_table_entry { - enum vmbus_channel_message_type message_type; - void (*message_handler)(struct vmbus_channel_message_header *msg); -}; - struct vmbus_rescind_work { struct work_struct work; struct vmbus_channel *channel; @@ -827,25 +822,25 @@ static void vmbus_onversion_response( } /* Channel message dispatch table */ -static struct vmbus_channel_message_table_entry +struct vmbus_channel_message_table_entry channel_message_table[CHANNELMSG_COUNT] = { - {CHANNELMSG_INVALID, NULL}, - {CHANNELMSG_OFFERCHANNEL, vmbus_onoffer}, - {CHANNELMSG_RESCIND_CHANNELOFFER, vmbus_onoffer_rescind}, - {CHANNELMSG_REQUESTOFFERS, NULL}, - {CHANNELMSG_ALLOFFERS_DELIVERED, vmbus_onoffers_delivered}, - {CHANNELMSG_OPENCHANNEL, NULL}, - {CHANNELMSG_OPENCHANNEL_RESULT, vmbus_onopen_result}, - {CHANNELMSG_CLOSECHANNEL, NULL}, - {CHANNELMSG_GPADL_HEADER, NULL}, - {CHANNELMSG_GPADL_BODY, NULL}, - {CHANNELMSG_GPADL_CREATED, vmbus_ongpadl_created}, - {CHANNELMSG_GPADL_TEARDOWN, NULL}, - {CHANNELMSG_GPADL_TORNDOWN, vmbus_ongpadl_torndown}, - {CHANNELMSG_RELID_RELEASED, NULL}, - {CHANNELMSG_INITIATE_CONTACT, NULL}, - {CHANNELMSG_VERSION_RESPONSE, vmbus_onversion_response}, - {CHANNELMSG_UNLOAD, NULL}, + {CHANNELMSG_INVALID, 0, NULL}, + {CHANNELMSG_OFFERCHANNEL, 0, vmbus_onoffer}, + {CHANNELMSG_RESCIND_CHANNELOFFER, 0, vmbus_onoffer_rescind}, + {CHANNELMSG_REQUESTOFFERS, 0, NULL}, + {CHANNELMSG_ALLOFFERS_DELIVERED, 1, vmbus_onoffers_delivered}, + {CHANNELMSG_OPENCHANNEL, 0, NULL}, + {CHANNELMSG_OPENCHANNEL_RESULT, 1, vmbus_onopen_result}, + {CHANNELMSG_CLOSECHANNEL, 0, NULL}, + {CHANNELMSG_GPADL_HEADER, 0, NULL}, + {CHANNELMSG_GPADL_BODY, 0, NULL}, + {CHANNELMSG_GPADL_CREATED, 1, vmbus_ongpadl_created}, + {CHANNELMSG_GPADL_TEARDOWN, 0, NULL}, + {CHANNELMSG_GPADL_TORNDOWN, 1, vmbus_ongpadl_torndown}, + {CHANNELMSG_RELID_RELEASED, 0, NULL}, + {CHANNELMSG_INITIATE_CONTACT, 0, NULL}, + {CHANNELMSG_VERSION_RESPONSE, 1, vmbus_onversion_response}, + {CHANNELMSG_UNLOAD, 0, NULL}, }; /* diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h index c8e27e0fdc99..f40a5a935ab6 100644 --- a/drivers/hv/hyperv_vmbus.h +++ b/drivers/hv/hyperv_vmbus.h @@ -685,6 +685,23 @@ struct vmbus_msginfo { extern struct vmbus_connection vmbus_connection; +enum vmbus_message_handler_type { + /* The related handler can sleep. */ + VMHT_BLOCKING = 0, + + /* The related handler must NOT sleep. */ + VMHT_NON_BLOCKING = 1, +}; + +struct vmbus_channel_message_table_entry { + enum vmbus_channel_message_type message_type; + enum vmbus_message_handler_type handler_type; + void (*message_handler)(struct vmbus_channel_message_header *msg); +}; + +extern struct vmbus_channel_message_table_entry + channel_message_table[CHANNELMSG_COUNT]; + /* General vmbus interface */ struct hv_device *vmbus_device_create(const uuid_le *type, diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 8313e25378cb..c85235e9f245 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -657,21 +657,36 @@ static void vmbus_on_msg_dpc(unsigned long data) void *page_addr = hv_context.synic_message_page[cpu]; struct hv_message *msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT; + struct vmbus_channel_message_header *hdr; + struct vmbus_channel_message_table_entry *entry; struct onmessage_work_context *ctx; while (1) { - if (msg->header.message_type == HVMSG_NONE) { + if (msg->header.message_type == HVMSG_NONE) /* no msg */ break; - } else { + + hdr = (struct vmbus_channel_message_header *)msg->u.payload; + + if (hdr->msgtype >= CHANNELMSG_COUNT) { + WARN_ONCE(1, "unknown msgtype=%d\n", hdr->msgtype); + goto msg_handled; + } + + entry = &channel_message_table[hdr->msgtype]; + if (entry->handler_type == VMHT_BLOCKING) { ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC); if (ctx == NULL) continue; + INIT_WORK(&ctx->work, vmbus_onmessage_work); memcpy(&ctx->msg, msg, sizeof(*msg)); + queue_work(vmbus_connection.work_queue, &ctx->work); - } + } else + entry->message_handler(hdr); +msg_handled: msg->header.message_type = HVMSG_NONE; /* -- 2.39.5