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| author | K. Y. Srinivasan <kys@microsoft.com> | 2017-08-11 19:03:59 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-08-16 18:16:29 +0200 |
| commit | 6f3d791f300618caf82a2be0c27456edd76d5164 (patch) | |
| tree | b92051bd127b0e5a0482f7eabe9d97e1986c9c00 /drivers/hv/channel_mgmt.c | |
| parent | Tools: hv: update buffer handling in hv_fcopy_daemon (diff) | |
| download | linux-6f3d791f300618caf82a2be0c27456edd76d5164.tar.xz linux-6f3d791f300618caf82a2be0c27456edd76d5164.zip | |
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 Since the host does not respond to messages on a rescinded channel,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 When a rescinded channel is being closed, if there is a pending interrupt on the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: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Tested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/hv/channel_mgmt.c')
| -rw-r--r-- | drivers/hv/channel_mgmt.c | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 4bbb8dea4727..968af173c4c1 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -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); |