From: "K. Y. Srinivasan" <k...@microsoft.com>
This patch addresses the following bugs in the current rescind handling code:
1. Fixes a race condition where we may be invoking hv_process_channel_removal()
on an already freed channel.
2. Prevents indefinite wait when rescinding sub-channels by correctly setting
the probe_complete state.
I would like to thank Dexuan for patiently reviewing earlier versions of this
patch and identifying many of the issues fixed here.
Greg, please apply this to 4.14-final.
Fixes: '54a66265d675 ("Drivers: hv: vmbus: Fix rescind handling")'
Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
Reviewed-by: Dexuan Cui <de...@microsoft.com>
Cc: sta...@vger.kernel.org (4.13 and above)
---
drivers/hv/channel.c | 6 +++---
drivers/hv/channel_mgmt.c | 37 ++++++++++++++++++-------------------
drivers/hv/vmbus_drv.c | 3 +--
include/linux/hyperv.h | 2 +-
4 files changed, 23 insertions(+), 25 deletions(-)
diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 63ac1c6a825f..be3fccab07fe 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -640,6 +640,7 @@ void vmbus_close(struct vmbus_channel *channel)
*/
return;
}
+ mutex_lock(&vmbus_connection.channel_mutex);
/*
* Close all the sub-channels first and then close the
* primary channel.
@@ -648,16 +649,15 @@ void vmbus_close(struct vmbus_channel *channel)
cur_channel = list_entry(cur, struct vmbus_channel, sc_list);
vmbus_close_internal(cur_channel);
if (cur_channel->rescind) {
- mutex_lock(&vmbus_connection.channel_mutex);
- hv_process_channel_removal(cur_channel,
+ hv_process_channel_removal(
cur_channel->offermsg.child_relid);
- mutex_unlock(&vmbus_connection.channel_mutex);
}
}
/*
* Now close the primary.
*/
vmbus_close_internal(channel);
+ mutex_unlock(&vmbus_connection.channel_mutex);
}
EXPORT_SYMBOL_GPL(vmbus_close);
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 624d815745e4..18c94ed02562 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -159,7 +159,7 @@ static void vmbus_rescind_cleanup(struct vmbus_channel
*channel)
spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
-
+ channel->rescind = true;
list_for_each_entry(msginfo, &vmbus_connection.chn_msg_list,
msglistentry) {
@@ -381,14 +381,21 @@ static void vmbus_release_relid(u32 relid)
true);
}
-void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid)
+void hv_process_channel_removal(u32 relid)
{
unsigned long flags;
- struct vmbus_channel *primary_channel;
+ struct vmbus_channel *primary_channel, *channel;
- BUG_ON(!channel->rescind);
BUG_ON(!mutex_is_locked(&vmbus_connection.channel_mutex));
+ /*
+ * Make sure channel is valid as we may have raced.
+ */
+ channel = relid2channel(relid);
+ if (!channel)
+ return;
+
+ BUG_ON(!channel->rescind);
if (channel->target_cpu != get_cpu()) {
put_cpu();
smp_call_function_single(channel->target_cpu,
@@ -515,6 +522,7 @@ static void vmbus_process_offer(struct vmbus_channel
*newchannel)
if (!fnew) {
if (channel->sc_creation_callback != NULL)
channel->sc_creation_callback(newchannel);
+ newchannel->probe_done = true;
return;
}
@@ -843,7 +851,6 @@ static void vmbus_onoffer_rescind(struct
vmbus_channel_message_header *hdr)
{
struct vmbus_channel_rescind_offer *rescind;
struct vmbus_channel *channel;
- unsigned long flags;
struct device *dev;
rescind = (struct vmbus_channel_rescind_offer *)hdr;
@@ -882,16 +889,6 @@ static void vmbus_onoffer_rescind(struct
vmbus_channel_message_header *hdr)
return;
}
- spin_lock_irqsave(&channel->lock, flags);
- channel->rescind = true;
- spin_unlock_irqrestore(&channel->lock, flags);
-
- /*
- * Now that we have posted the rescind state, perform
- * rescind related cleanup.
- */
- vmbus_rescind_cleanup(channel);
-
/*
* Now wait for offer handling to complete.
*/
@@ -910,6 +907,7 @@ 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);
+ vmbus_rescind_cleanup(channel);
return;
}
/*
@@ -918,6 +916,7 @@ static void vmbus_onoffer_rescind(struct
vmbus_channel_message_header *hdr)
*/
dev = get_device(&channel->device_obj->device);
if (dev) {
+ vmbus_rescind_cleanup(channel);
vmbus_device_unregister(channel->device_obj);
put_device(dev);
}
@@ -930,16 +929,16 @@ static void vmbus_onoffer_rescind(struct
vmbus_channel_message_header *hdr)
* 1. Close all sub-channels first
* 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.
*/
- mutex_lock(&vmbus_connection.channel_mutex);
- hv_process_channel_removal(channel,
- channel->offermsg.child_relid);
- mutex_unlock(&vmbus_connection.channel_mutex);
+ hv_process_channel_removal(rescind->child_relid);
}
+ mutex_unlock(&vmbus_connection.channel_mutex);
}
}
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 43160a2eafe0..5ad627044dd1 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -768,8 +768,7 @@ static void vmbus_device_release(struct device *device)
struct vmbus_channel *channel = hv_dev->channel;
mutex_lock(&vmbus_connection.channel_mutex);
- hv_process_channel_removal(channel,
- channel->offermsg.child_relid);
+ hv_process_channel_removal(channel->offermsg.child_relid);
mutex_unlock(&vmbus_connection.channel_mutex);
kfree(hv_dev);
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 07650d0232cc..d0202ea5ca1e 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1439,7 +1439,7 @@ extern bool vmbus_prep_negotiate_resp(struct icmsg_hdr
*icmsghdrp, u8 *buf,
const int *srv_version, int srv_vercnt,
int *nego_fw_version, int *nego_srv_version);
-void hv_process_channel_removal(struct vmbus_channel *channel, u32 relid);
+void hv_process_channel_removal(u32 relid);
void vmbus_setevent(struct vmbus_channel *channel);
/*
--
2.14.1
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