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Commit dad76bf7 authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman
Browse files

Staging: hv: vmbus: Properly deal with de-registering channel callback 



Ensure that we correctly handle racing invocations of the channel callback
when the channel is being closed. We do this using the channel's inbound_lock.
A side-effect of this strategy is that we avoid repeatedly picking up this lock
as we drain the inbound ring-buffer.

Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 76c39d42

drivers/staging/hv/channel.c

+5 −15
Original line number Diff line number Diff line
@@ -513,9 +513,12 @@ void vmbus_close(struct vmbus_channel *channel) 
{

	struct vmbus_channel_close_channel *msg;

	int ret;

	unsigned long flags;



	/* Stop callback and cancel the timer asap */

	spin_lock_irqsave(&channel->inbound_lock, flags);

	channel->onchannel_callback = NULL;

	spin_unlock_irqrestore(&channel->inbound_lock, flags);



	/* Send a closing message */
@@ -735,19 +738,15 @@ int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer, 
	u32 packetlen;

	u32 userlen;

	int ret;

	unsigned long flags;



	*buffer_actual_len = 0;

	*requestid = 0;



	spin_lock_irqsave(&channel->inbound_lock, flags);



	ret = hv_ringbuffer_peek(&channel->inbound, &desc,

			     sizeof(struct vmpacket_descriptor));

	if (ret != 0) {

		spin_unlock_irqrestore(&channel->inbound_lock, flags);

	if (ret != 0)

		return 0;

	}



	packetlen = desc.len8 << 3;

	userlen = packetlen - (desc.offset8 << 3);
@@ -755,7 +754,6 @@ int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer, 
	*buffer_actual_len = userlen;



	if (userlen > bufferlen) {

		spin_unlock_irqrestore(&channel->inbound_lock, flags);



		pr_err("Buffer too small - got %d needs %d\n",

			   bufferlen, userlen);
@@ -768,7 +766,6 @@ int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer, 
	ret = hv_ringbuffer_read(&channel->inbound, buffer, userlen,

			     (desc.offset8 << 3));



	spin_unlock_irqrestore(&channel->inbound_lock, flags);



	return 0;

}
@@ -785,19 +782,15 @@ int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer, 
	u32 packetlen;

	u32 userlen;

	int ret;

	unsigned long flags;



	*buffer_actual_len = 0;

	*requestid = 0;



	spin_lock_irqsave(&channel->inbound_lock, flags);



	ret = hv_ringbuffer_peek(&channel->inbound, &desc,

			     sizeof(struct vmpacket_descriptor));

	if (ret != 0) {

		spin_unlock_irqrestore(&channel->inbound_lock, flags);

	if (ret != 0)

		return 0;

	}





	packetlen = desc.len8 << 3;
@@ -806,8 +799,6 @@ int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer, 
	*buffer_actual_len = packetlen;



	if (packetlen > bufferlen) {

		spin_unlock_irqrestore(&channel->inbound_lock, flags);



		pr_err("Buffer too small - needed %d bytes but "

			"got space for only %d bytes\n",

			packetlen, bufferlen);
@@ -819,7 +810,6 @@ int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer, 
	/* Copy over the entire packet to the user buffer */

	ret = hv_ringbuffer_read(&channel->inbound, buffer, packetlen, 0);



	spin_unlock_irqrestore(&channel->inbound_lock, flags);

	return 0;

}

EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);

drivers/staging/hv/connection.c

+3 −0
Original line number Diff line number Diff line
@@ -215,6 +215,7 @@ struct vmbus_channel *relid2channel(u32 relid) 
static void process_chn_event(u32 relid)

{

	struct vmbus_channel *channel;

	unsigned long flags;



	/*

	 * Find the channel based on this relid and invokes the
@@ -222,11 +223,13 @@ static void process_chn_event(u32 relid) 
	 */

	channel = relid2channel(relid);



	spin_lock_irqsave(&channel->inbound_lock, flags);

	if (channel && (channel->onchannel_callback != NULL)) {

		channel->onchannel_callback(channel->channel_callback_context);

	} else {

		pr_err("channel not found for relid - %u\n", relid);

	}

	spin_unlock_irqrestore(&channel->inbound_lock, flags);

}



/*

drivers/staging/hv/netvsc.c

+0 −3
Original line number Diff line number Diff line
@@ -62,9 +62,7 @@ static struct netvsc_device *get_outbound_net_device(struct hv_device *device) 
static struct netvsc_device *get_inbound_net_device(struct hv_device *device)

{

	struct netvsc_device *net_device;

	unsigned long flags;



	spin_lock_irqsave(&device->channel->inbound_lock, flags);

	net_device = device->ext;



	if (!net_device)
@@ -75,7 +73,6 @@ static struct netvsc_device *get_inbound_net_device(struct hv_device *device) 
		net_device = NULL;



get_in_err:

	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

	return net_device;

}

drivers/staging/hv/storvsc_drv.c

+0 −3
Original line number Diff line number Diff line
@@ -352,9 +352,7 @@ static inline struct storvsc_device *get_in_stor_device( 
					struct hv_device *device)

{

	struct storvsc_device *stor_device;

	unsigned long flags;



	spin_lock_irqsave(&device->channel->inbound_lock, flags);

	stor_device = (struct storvsc_device *)device->ext;



	if (!stor_device)
@@ -370,7 +368,6 @@ static inline struct storvsc_device *get_in_stor_device( 
		stor_device = NULL;



get_in_err:

	spin_unlock_irqrestore(&device->channel->inbound_lock, flags);

	return stor_device;



}