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authorVitaly Kuznetsov <vkuznets@redhat.com>2016-12-07 01:16:24 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-01-10 21:46:40 +0100
commitc0bb03924f1a80e7f65900e36c8e6b3dc167c5f8 (patch)
treeee5573cc22c8c8cd01a365743ec6d010e77742e7 /drivers/hv/connection.c
parenta121103c922847ba5010819a3f250f1f7fc84ab8 (diff)
Drivers: hv: vmbus: Raise retry/wait limits in vmbus_post_msg()
DoS protection conditions were altered in WS2016 and now it's easy to get -EAGAIN returned from vmbus_post_msg() (e.g. when we try changing MTU on a netvsc device in a loop). All vmbus_post_msg() callers don't retry the operation and we usually end up with a non-functional device or crash. While host's DoS protection conditions are unknown to me my tests show that it can take up to 10 seconds before the message is sent so doing udelay() is not an option, we really need to sleep. Almost all vmbus_post_msg() callers are ready to sleep but there is one special case: vmbus_initiate_unload() which can be called from interrupt/NMI context and we can't sleep there. I'm also not sure about the lonely vmbus_send_tl_connect_request() which has no in-tree users but its external users are most likely waiting for the host to reply so sleeping there is also appropriate. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Cc: <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv/connection.c')
-rw-r--r--drivers/hv/connection.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index 6ce8b874e833..9b72ebcd37bc 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -111,7 +111,8 @@ static int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo,
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
ret = vmbus_post_msg(msg,
- sizeof(struct vmbus_channel_initiate_contact));
+ sizeof(struct vmbus_channel_initiate_contact),
+ true);
if (ret != 0) {
spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
list_del(&msginfo->msglistentry);
@@ -435,7 +436,7 @@ void vmbus_on_event(unsigned long data)
/*
* vmbus_post_msg - Send a msg on the vmbus's message connection
*/
-int vmbus_post_msg(void *buffer, size_t buflen)
+int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)
{
union hv_connection_id conn_id;
int ret = 0;
@@ -450,7 +451,7 @@ int vmbus_post_msg(void *buffer, size_t buflen)
* insufficient resources. Retry the operation a couple of
* times before giving up.
*/
- while (retries < 20) {
+ while (retries < 100) {
ret = hv_post_message(conn_id, 1, buffer, buflen);
switch (ret) {
@@ -473,8 +474,14 @@ int vmbus_post_msg(void *buffer, size_t buflen)
}
retries++;
- udelay(usec);
- if (usec < 2048)
+ if (can_sleep && usec > 1000)
+ msleep(usec / 1000);
+ else if (usec < MAX_UDELAY_MS * 1000)
+ udelay(usec);
+ else
+ mdelay(usec / 1000);
+
+ if (usec < 256000)
usec *= 2;
}
return ret;