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Staging: hv: vmbus: Cleanup the code in process_chn_event()

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A channel in Hyper-V is equivalent to a device. Thus, a channel is
persistent once it is presented to the guest, even if the driver
managing this device is unloaded. By checking and invoking the driver
specific callback function under the protection of the channel
inbound_lock, we can properly deal with racing driver unloads since an
unloading driver sets the callback to NULL under the protection of this
inbound_lock.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
K. Y. Srinivasan 2011-08-31 14:35:57 -07:00 committed by Greg Kroah-Hartman
parent 7341d908af
commit 24326039b9
1 changed files with 16 additions and 2 deletions
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18
drivers/staging/hv/connection.c
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@ -219,11 +219,25 @@ static void process_chn_event(u32 relid)
*/ */
channel = relid2channel(relid); channel = relid2channel(relid);
if (!channel) {
pr_err("channel not found for relid - %u\n", relid);
return;
}
/*
* A channel once created is persistent even when there
* is no driver handling the device. An unloading driver
* sets the onchannel_callback to NULL under the
* protection of the channel inbound_lock. Thus, checking
* and invoking the driver specific callback takes care of
* orderly unloading of the driver.
*/
spin_lock_irqsave(&channel->inbound_lock, flags); spin_lock_irqsave(&channel->inbound_lock, flags);
if (channel && (channel->onchannel_callback != NULL)) if (channel->onchannel_callback != NULL)
channel->onchannel_callback(channel->channel_callback_context); channel->onchannel_callback(channel->channel_callback_context);
else else
pr_err("channel not found for relid - %u\n", relid); pr_err("no channel callback for relid - %u\n", relid);
spin_unlock_irqrestore(&channel->inbound_lock, flags); spin_unlock_irqrestore(&channel->inbound_lock, flags);
} }