Commit 6f3d791f authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman

Drivers: hv: vmbus: Fix rescind handling issues

This patch handles the following issues that were observed when we are
handling racing channel offer message and rescind message for the same
offer:

1. Since the host does not respond to messages on a rescinded channel,
in the current code, we could be indefinitely blocked on the vmbus_open() call.

2. When a rescinded channel is being closed, if there is a pending interrupt on the
channel, we could end up freeing the channel that the interrupt handler would run on.
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: default avatarDexuan Cui <decui@microsoft.com>
Tested-by: default avatarDexuan Cui <decui@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3f2baa8a
......@@ -177,6 +177,11 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size,
&vmbus_connection.chn_msg_list);
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
if (newchannel->rescind) {
err = -ENODEV;
goto error_free_gpadl;
}
ret = vmbus_post_msg(open_msg,
sizeof(struct vmbus_channel_open_channel), true);
......@@ -421,6 +426,11 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
if (channel->rescind) {
ret = -ENODEV;
goto cleanup;
}
ret = vmbus_post_msg(gpadlmsg, msginfo->msgsize -
sizeof(*msginfo), true);
if (ret != 0)
......@@ -494,6 +504,10 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel, u32 gpadl_handle)
list_add_tail(&info->msglistentry,
&vmbus_connection.chn_msg_list);
spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
if (channel->rescind)
goto post_msg_err;
ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_gpadl_teardown),
true);
......
......@@ -451,6 +451,12 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
/* Make sure this is a new offer */
mutex_lock(&vmbus_connection.channel_mutex);
/*
* Now that we have acquired the channel_mutex,
* we can release the potentially racing rescind thread.
*/
atomic_dec(&vmbus_connection.offer_in_progress);
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
if (!uuid_le_cmp(channel->offermsg.offer.if_type,
newchannel->offermsg.offer.if_type) &&
......@@ -481,7 +487,6 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
channel->num_sc++;
spin_unlock_irqrestore(&channel->lock, flags);
} else {
atomic_dec(&vmbus_connection.offer_in_progress);
goto err_free_chan;
}
}
......@@ -510,7 +515,6 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
if (!fnew) {
if (channel->sc_creation_callback != NULL)
channel->sc_creation_callback(newchannel);
atomic_dec(&vmbus_connection.offer_in_progress);
return;
}
......@@ -541,7 +545,7 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
goto err_deq_chan;
}
atomic_dec(&vmbus_connection.offer_in_progress);
newchannel->probe_done = true;
return;
err_deq_chan:
......@@ -882,8 +886,27 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
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.
*/
while (READ_ONCE(channel->probe_done) == false) {
/*
* We wait here until any channel offer is currently
* being processed.
*/
msleep(1);
}
/*
* At this point, the rescind handling can proceed safely.
*/
if (channel->device_obj) {
if (channel->chn_rescind_callback) {
channel->chn_rescind_callback(channel);
......
......@@ -940,6 +940,9 @@ static void vmbus_chan_sched(struct hv_per_cpu_context *hv_cpu)
if (channel->offermsg.child_relid != relid)
continue;
if (channel->rescind)
continue;
switch (channel->callback_mode) {
case HV_CALL_ISR:
vmbus_channel_isr(channel);
......
......@@ -879,6 +879,8 @@ struct vmbus_channel {
*/
enum hv_numa_policy affinity_policy;
bool probe_done;
};
static inline bool is_hvsock_channel(const struct vmbus_channel *c)
......
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