From: Dexuan Cui <decui@microsoft.com>
Date: Thu, 15 Mar 2018 14:22:00 +0000
Subject: PCI: hv: Only queue new work items in hv_pci_devices_present() if necessary
Patch-mainline: v4.17-rc1
Git-commit: 948373b3ed1bcf05a237c24675b84804315aff14
References: fate#323887, bsc#1087659
If there is pending work in hv_pci_devices_present() we just need to add
the new dr entry into the dr_list. Add a check to detect pending work
items and update the code to skip queuing work if pending work items
are detected.
Signed-off-by: Dexuan Cui <decui@microsoft.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Jack Morgenstein <jackm@mellanox.com>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Acked-by: Olaf Hering <ohering@suse.de>
---
drivers/pci/host/pci-hyperv.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1789,6 +1789,7 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
struct hv_dr_state *dr;
struct hv_dr_work *dr_wrk;
unsigned long flags;
+ bool pending_dr;
dr_wrk = kzalloc(sizeof(*dr_wrk), GFP_NOWAIT);
if (!dr_wrk)
@@ -1812,11 +1813,21 @@ static void hv_pci_devices_present(struct hv_pcibus_device *hbus,
}
spin_lock_irqsave(&hbus->device_list_lock, flags);
+ /*
+ * If pending_dr is true, we have already queued a work,
+ * which will see the new dr. Otherwise, we need to
+ * queue a new work.
+ */
+ pending_dr = !list_empty(&hbus->dr_list);
list_add_tail(&dr->list_entry, &hbus->dr_list);
spin_unlock_irqrestore(&hbus->device_list_lock, flags);
- get_hvpcibus(hbus);
- queue_work(hbus->wq, &dr_wrk->wrk);
+ if (pending_dr) {
+ kfree(dr_wrk);
+ } else {
+ get_hvpcibus(hbus);
+ queue_work(hbus->wq, &dr_wrk->wrk);
+ }
}
/**