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

Message ID 20180306182128.23281-5-decui@microsoft.com
State Superseded
Delegated to: Lorenzo Pieralisi
Headers show
Series
  • some fixes to the pci-hyperv driver.
Related show

Commit Message

Dexuan Cui March 6, 2018, 6:21 p.m.
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(-)

Comments

Michael Kelley (EOSG) March 6, 2018, 6:31 p.m. | #1
> -----Original Message-----
> From: Dexuan Cui
> Sent: Tuesday, March 6, 2018 10:22 AM
> To: bhelgaas@google.com; linux-pci@vger.kernel.org; KY Srinivasan <kys@microsoft.com>;
> Stephen Hemminger <sthemmin@microsoft.com>; olaf@aepfle.de; apw@canonical.com;
> jasowang@redhat.com
> Cc: linux-kernel@vger.kernel.org; driverdev-devel@linuxdriverproject.org; Haiyang Zhang
> <haiyangz@microsoft.com>; vkuznets@redhat.com; marcelo.cerri@canonical.com; Michael
> Kelley (EOSG) <Michael.H.Kelley@microsoft.com>; Dexuan Cui <decui@microsoft.com>; Jack
> Morgenstein <jackm@mellanox.com>; stable@vger.kernel.org
> Subject: [PATCH v3 4/6] PCI: hv: remove hbus->enum_sem
> 
> 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(-)
> 

Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Haiyang Zhang March 9, 2018, 7:37 p.m. | #2
> -----Original Message-----
> From: Dexuan Cui
> Sent: Tuesday, March 6, 2018 1:22 PM
> To: bhelgaas@google.com; linux-pci@vger.kernel.org; KY Srinivasan
> <kys@microsoft.com>; Stephen Hemminger <sthemmin@microsoft.com>;
> olaf@aepfle.de; apw@canonical.com; jasowang@redhat.com
> Cc: linux-kernel@vger.kernel.org; driverdev-devel@linuxdriverproject.org;
> Haiyang Zhang <haiyangz@microsoft.com>; vkuznets@redhat.com;
> marcelo.cerri@canonical.com; Michael Kelley (EOSG)
> <Michael.H.Kelley@microsoft.com>; Dexuan Cui <decui@microsoft.com>; Jack
> Morgenstein <jackm@mellanox.com>; stable@vger.kernel.org
> Subject: [PATCH v3 4/6] PCI: hv: remove hbus->enum_sem
> 
> 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>
> ---

Acked-by: Haiyang Zhang <haiyangz@microsoft.com>

Patch

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);