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authorDexuan Cui <decui@microsoft.com>2015-03-27 09:10:08 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-04-03 16:18:01 +0200
commit652594c7dfd9bf6392e3a727bc69d89a2562d953 (patch)
tree6f40c87328a8d8e2880d8a4a6feb3f3fdb1c6caf
parent01081f5ab9916603555f236b11f76bb00e4e01e9 (diff)
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op-kernel-dev-652594c7dfd9bf6392e3a727bc69d89a2562d953.tar.gz
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 <decui@microsoft.com> Cc: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/hv/channel_mgmt.c41
-rw-r--r--drivers/hv/hyperv_vmbus.h17
-rw-r--r--drivers/hv/vmbus_drv.c21
3 files changed, 53 insertions, 26 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index bb39705..287f07b 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 c8e27e0..f40a5a9 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 8313e25..c85235e 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;
/*
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