From: "Andrea Parri (Microsoft)" <parri.andrea@gmail.com>
Date: Wed, 17 Jun 2020 18:46:38 +0200
Patch-mainline: v5.9-rc1
Subject: Drivers: hv: vmbus: Remove unnecessary channel->lock critical sections (sc_list readers)
Git-commit: 12d0dd8e728e785e6fb81f5232280678bc69d8dc
References: jsc#sle-12891
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>
Acked-by: Olaf Hering <ohering@suse.de>
---
drivers/hv/hv.c | 3 ---
drivers/hv/vmbus_drv.c | 3 ---
2 files changed, 6 deletions(-)
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
--- 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
--- 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);
}