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: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-9-parri.andrea@gmail.com
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 8848d15..3ebda77 100644 (file)
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -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;

diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 92f8bb2..591106c 100644 (file)
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -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);

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 690394b..38100e8 100644 (file)
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -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.
         */