[SRU,Bionic,3/3] PCI: hv: Only queue new work items in hv_pci_devices_present() if necessary

Message ID 20180608183911.24395-4-marcelo.cerri@canonical.com
State New
Headers show
Series
  • PCI: hv: Fix 2 hang issues in hv_compose_msi_msg
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Commit Message

Marcelo Henrique Cerri June 8, 2018, 6:39 p.m.
From: Dexuan Cui <decui@microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1758378

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>
(cherry picked from commit 948373b3ed1bcf05a237c24675b84804315aff14)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
---
 drivers/pci/host/pci-hyperv.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Patch

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 5eb7954ee584..f7d36c03486c 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1801,6 +1801,7 @@  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)
@@ -1824,11 +1825,21 @@  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);
+	}
 }
 
 /**