Commit 775f43fa authored by Andrea Parri (Microsoft)'s avatar Andrea Parri (Microsoft) Committed by Wei Liu
Browse files

Drivers: hv: vmbus: Remove the lock field from the vmbus_channel struct 



The spinlock is (now) *not used to protect test-and-set accesses
to attributes of the structure or sc_list operations.

There is, AFAICT, a distinct lack of {WRITE,READ}_ONCE()s in the
handling of channel->state, but the changes below do not seem to
make things "worse".  ;-)

Signed-off-by: default avatarAndrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-9-parri.andrea@gmail.com


Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarWei Liu <wei.liu@kernel.org>
parent 21d2052c

drivers/hv/channel.c

+1 −5
Original line number Diff line number Diff line
@@ -129,12 +129,8 @@ static int __vmbus_open(struct vmbus_channel *newchannel, 
	send_pages = newchannel->ringbuffer_send_offset;

	recv_pages = newchannel->ringbuffer_pagecount - send_pages;



	spin_lock_irqsave(&newchannel->lock, flags);

	if (newchannel->state != CHANNEL_OPEN_STATE) {

		spin_unlock_irqrestore(&newchannel->lock, flags);

	if (newchannel->state != CHANNEL_OPEN_STATE)

		return -EINVAL;

	}

	spin_unlock_irqrestore(&newchannel->lock, flags);



	newchannel->state = CHANNEL_OPENING_STATE;

	newchannel->onchannel_callback = onchannelcallback;

drivers/hv/channel_mgmt.c

+0 −1
Original line number Diff line number Diff line
@@ -317,7 +317,6 @@ static struct vmbus_channel *alloc_channel(void) 
		return NULL;



	spin_lock_init(&channel->sched_lock);

	spin_lock_init(&channel->lock);

	init_completion(&channel->rescind_event);



	INIT_LIST_HEAD(&channel->sc_list);

include/linux/hyperv.h

+0 −6
Original line number Diff line number Diff line
@@ -840,12 +840,6 @@ struct vmbus_channel { 
	 */

	void (*chn_rescind_callback)(struct vmbus_channel *channel);



	/*

	 * The spinlock to protect the structure. It is being used to protect

	 * test-and-set access to various attributes of the structure as well

	 * as all sc_list operations.

	 */

	spinlock_t lock;

	/*

	 * All Sub-channels of a primary channel are linked here.

	 */

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