[PATCH] PCI: hv: add hard timeout to wait_for_response()

[Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>]

It is possible that we never receive a rescind event, in which case we
will wait indefinitely for a device that will never show up. So, assume
a device is gone if have been polling for more than 5 seconds.

Cc: stable@vger.kernel.org
Fixes: c3635da2a336 ("PCI: hv: Do not wait forever on a device that has disappeared")
Signed-off-by: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com>
---
 drivers/pci/controller/pci-hyperv.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index cfc8fa403dad..bd63efc4a210 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -52,6 +52,7 @@
 #include <linux/acpi.h>
 #include <linux/sizes.h>
 #include <linux/of_irq.h>
+#include <linux/jiffies.h>
 #include <asm/mshyperv.h>
 
 /*
@@ -1038,6 +1039,8 @@ static void put_pcichild(struct hv_pci_dev *hpdev)
 		kfree(hpdev);
 }
 
+#define TIMEOUT_MS 5000
+
 /*
  * There is no good way to get notified from vmbus_onoffer_rescind(),
  * so let's use polling here, since this is not a hot path.
@@ -1045,8 +1048,13 @@ static void put_pcichild(struct hv_pci_dev *hpdev)
 static int wait_for_response(struct hv_device *hdev,
 			     struct completion *comp)
 {
+	unsigned long timeout = get_jiffies_64() + msecs_to_jiffies(TIMEOUT_MS);
+	unsigned long now;
+
 	while (true) {
-		if (hdev->channel->rescind) {
+		now = get_jiffies_64();
+		if (hdev->channel->rescind ||
+		    time_after(now, timeout)) {
 			dev_warn_once(&hdev->device, "The device is gone.\n");
 			return -ENODEV;
 		}
-- 
2.54.0