Drivers: hv: vmbus: Remove unnecessary channel->lock critical sections (sc_list updaters)

None of the readers/updaters of sc_list rely on channel->lock for
synchronization.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-7-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_mgmt.c b/drivers/hv/channel_mgmt.c
index 36dd8b6c544a4d6af3027f9bb19109dad8742c5c..92f8bb2077a945fd23a599a4ac0df18b44185dce 100644 (file)
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -400,8 +400,6 @@ static void vmbus_release_relid(u32 relid)
 
 void hv_process_channel_removal(struct vmbus_channel *channel)
 {
-       unsigned long flags;
-
        lockdep_assert_held(&vmbus_connection.channel_mutex);
        BUG_ON(!channel->rescind);
 
@@ -422,14 +420,10 @@ void hv_process_channel_removal(struct vmbus_channel *channel)
        if (channel->offermsg.child_relid != INVALID_RELID)
                vmbus_channel_unmap_relid(channel);
 
-       if (channel->primary_channel == NULL) {
+       if (channel->primary_channel == NULL)
                list_del(&channel->listentry);
-       } else {
-               struct vmbus_channel *primary_channel = channel->primary_channel;
-               spin_lock_irqsave(&primary_channel->lock, flags);
+       else
                list_del(&channel->sc_list);
-               spin_unlock_irqrestore(&primary_channel->lock, flags);
-       }
 
        /*
         * If this is a "perf" channel, updates the hv_numa_map[] masks so that
@@ -470,7 +464,6 @@ static void vmbus_add_channel_work(struct work_struct *work)
        struct vmbus_channel *newchannel =
                container_of(work, struct vmbus_channel, add_channel_work);
        struct vmbus_channel *primary_channel = newchannel->primary_channel;
-       unsigned long flags;
        int ret;
 
        /*
@@ -531,13 +524,10 @@ err_deq_chan:
         */
        newchannel->probe_done = true;
 
-       if (primary_channel == NULL) {
+       if (primary_channel == NULL)
                list_del(&newchannel->listentry);
-       } else {
-               spin_lock_irqsave(&primary_channel->lock, flags);
+       else
                list_del(&newchannel->sc_list);
-               spin_unlock_irqrestore(&primary_channel->lock, flags);
-       }
 
        /* vmbus_process_offer() has mapped the channel. */
        vmbus_channel_unmap_relid(newchannel);
@@ -557,7 +547,6 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
 {
        struct vmbus_channel *channel;
        struct workqueue_struct *wq;
-       unsigned long flags;
        bool fnew = true;
 
        /*
@@ -609,10 +598,10 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
                }
        }
 
-       if (fnew)
+       if (fnew) {
                list_add_tail(&newchannel->listentry,
                              &vmbus_connection.chn_list);
-       else {
+       } else {
                /*
                 * Check to see if this is a valid sub-channel.
                 */
@@ -630,9 +619,7 @@ static void vmbus_process_offer(struct vmbus_channel *newchannel)
                 * Process the sub-channel.
                 */
                newchannel->primary_channel = channel;
-               spin_lock_irqsave(&channel->lock, flags);
                list_add_tail(&newchannel->sc_list, &channel->sc_list);
-               spin_unlock_irqrestore(&channel->lock, flags);
        }
 
        vmbus_channel_map_relid(newchannel);