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

Additions/deletions to/from sc_list (as well as modifications of
target_cpu(s)) are protected by channel_mutex, which hv_synic_cleanup()
and vmbus_bus_suspend() own for the duration of the channel->lock
critical section in question.

Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20200617164642.37393-5-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/hv.c b/drivers/hv/hv.c
index 857290d..da69338 100644 (file)
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -241,7 +241,6 @@ int hv_synic_cleanup(unsigned int cpu)
 {
        struct vmbus_channel *channel, *sc;
        bool channel_found = false;
-       unsigned long flags;
 
        /*
         * Hyper-V does not provide a way to change the connect CPU once
@@ -263,14 +262,12 @@ int hv_synic_cleanup(unsigned int cpu)
                        channel_found = true;
                        break;
                }
-               spin_lock_irqsave(&channel->lock, flags);
                list_for_each_entry(sc, &channel->sc_list, sc_list) {
                        if (sc->target_cpu == cpu) {
                                channel_found = true;
                                break;
                        }
                }
-               spin_unlock_irqrestore(&channel->lock, flags);
                if (channel_found)
                        break;
        }

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 5b07c5b..4844642 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -2344,7 +2344,6 @@ acpi_walk_err:
 static int vmbus_bus_suspend(struct device *dev)
 {
        struct vmbus_channel *channel, *sc;
-       unsigned long flags;
 
        while (atomic_read(&vmbus_connection.offer_in_progress) != 0) {
                /*
@@ -2402,12 +2401,10 @@ static int vmbus_bus_suspend(struct device *dev)
                        continue;
                }
 
-               spin_lock_irqsave(&channel->lock, flags);
                list_for_each_entry(sc, &channel->sc_list, sc_list) {
                        pr_err("Sub-channel not deleted!\n");
                        WARN_ON_ONCE(1);
                }
-               spin_unlock_irqrestore(&channel->lock, flags);
 
                atomic_inc(&vmbus_connection.nr_chan_fixup_on_resume);
        }