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authorK. Y. Srinivasan <kys@microsoft.com>2017-09-29 21:09:36 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-04 11:25:09 +0200
commit192b2d78722ffea188e5ec6ae5d55010dce05a4b (patch)
treef48582ce3f3c880fa6c57452abe029d66bad04ff /drivers/hv/channel_mgmt.c
parent688cb67839e852740d22cf763e5eafb27d5a6e53 (diff)
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Drivers: hv: vmbus: Fix bugs in rescind handling
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 <kys@microsoft.com> Reviewed-by: Dexuan Cui <decui@microsoft.com> Cc: stable@vger.kernel.org # (4.13 and above) Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv/channel_mgmt.c')
-rw-r--r--drivers/hv/channel_mgmt.c37
1 files changed, 18 insertions, 19 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index bcbb031f7263..018d2e0f8ec5 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;
}
@@ -834,7 +842,6 @@ 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;
@@ -873,16 +880,6 @@ 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.
*/
@@ -901,6 +898,7 @@ 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;
}
/*
@@ -909,6 +907,7 @@ 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);
}
@@ -921,16 +920,16 @@ 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);
}
}