[PATCH v3 4/6] PCI: hv: remove hbus->enum_sem

Dexuan Cui
2018-03-06T18:22:07Z

Since we serialize the present/eject work items now, we don't need the
semaphore any more.

This is suggested by Michael Kelley.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Jack Morgenstein <jackm@mellanox.com>
Cc: stable@vger.kernel.org
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Michael Kelley (EOSG) <Michael.H.Kelley@microsoft.com>
---
drivers/pci/host/pci-hyperv.c | 17 ++---------------
1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index aaee41faf55f..3a385212f666 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -447,7 +447,6 @@ struct hv_pcibus_device {
spinlock_t device_list_lock; /* Protect lists below */
void __iomem *cfg_addr;

- struct semaphore enum_sem;
struct list_head resources_for_children;

struct list_head children;
@@ -1592,12 +1591,8 @@ static struct hv_pci_dev *get_pcichild_wslot(struct hv_pcibus_device *hbus,
* It must also treat the omission of a previously observed device as
* notification that the device no longer exists.
*
- * Note that this function is a work item, and it may not be
- * invoked in the order that it was queued. Back to back
- * updates of the list of present devices may involve queuing
- * multiple work items, and this one may run before ones that
- * were sent later. As such, this function only does something
- * if is the last one in the queue.
+ * Note that this function is serialized with hv_eject_device_work(),
+ * because both are pushed to the ordered workqueue hbus->wq.
*/
static void pci_devices_present_work(struct work_struct *work)
{
@@ -1618,11 +1613,6 @@ static void pci_devices_present_work(struct work_struct *work)

INIT_LIST_HEAD(&removed);

- if (down_interruptible(&hbus->enum_sem)) {
- put_hvpcibus(hbus);
- return;
- }
-
/* Pull this off the queue and process it if it was the last one. */
spin_lock_irqsave(&hbus->device_list_lock, flags);
while (!list_empty(&hbus->dr_list)) {
@@ -1639,7 +1629,6 @@ static void pci_devices_present_work(struct work_struct *work)
spin_unlock_irqrestore(&hbus->device_list_lock, flags);

if (!dr) {
- up(&hbus->enum_sem);
put_hvpcibus(hbus);
return;
}
@@ -1726,7 +1715,6 @@ static void pci_devices_present_work(struct work_struct *work)
break;
}

- up(&hbus->enum_sem);
put_hvpcibus(hbus);
kfree(dr);
}
@@ -2460,7 +2448,6 @@ static int hv_pci_probe(struct hv_device *hdev,
spin_lock_init(&hbus->config_lock);
spin_lock_init(&hbus->device_list_lock);
spin_lock_init(&hbus->retarget_msi_interrupt_lock);
- sema_init(&hbus->enum_sem, 1);
init_completion(&hbus->remove_event);
hbus->wq = alloc_ordered_workqueue("hv_pci_%x", 0,
hbus->sysdata.domain);
--
2.7.4