linux-kernel - [PATCH 2/3] PCI: hv: Add hv_pci_remove

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Message-ID: <20190304213357.16652-3-decui@microsoft.com>
Date:   Mon, 4 Mar 2019 21:34:48 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Michael Kelley <mikelley@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
CC:     "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "driverdev-devel@...uxdriverproject.org" 
        <driverdev-devel@...uxdriverproject.org>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "apw@...onical.com" <apw@...onical.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        vkuznets <vkuznets@...hat.com>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        "jackm@...lanox.com" <jackm@...lanox.com>,
        Dexuan Cui <decui@...rosoft.com>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: [PATCH 2/3] PCI: hv: Add hv_pci_remove_slots() when we unload the
 driver

When we unload pci-hyperv, the host doesn't send us a PCI_EJECT message.
In this case we also need to make sure the sysfs pci slot directory
is removed, otherwise "cat /sys/bus/pci/slots/2/address" will trigger
"BUG: unable to handle kernel paging request" (I noticed the issue when
systemd-dev crashed for me when I unloaded the driver). And, if we
unload/reload the driver several times, we'll have multiple pci slot
directories in /sys/bus/pci/slots/ like this:

root@...alhost:~# ls -rtl  /sys/bus/pci/slots/
total 0
drwxr-xr-x 2 root root 0 Feb  7 10:49 2
drwxr-xr-x 2 root root 0 Feb  7 10:49 2-1
drwxr-xr-x 2 root root 0 Feb  7 10:51 2-2

The patch adds the missing code.

Fixes: a15f2c08c708 ("PCI: hv: support reporting serial number as slot information")
Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Acked-by: Stephen Hemminger <sthemmin@...rosoft.com>
Cc: stable@...r.kernel.org
---
 drivers/pci/controller/pci-hyperv.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 30f16b882746..b489412e3502 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1486,6 +1486,21 @@ static void hv_pci_assign_slots(struct hv_pcibus_device *hbus)
 	}
 }
 
+/*
+ * Remove entries in sysfs pci slot directory.
+ */
+static void hv_pci_remove_slots(struct hv_pcibus_device *hbus)
+{
+	struct hv_pci_dev *hpdev;
+
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		if (!hpdev->pci_slot)
+			continue;
+		pci_destroy_slot(hpdev->pci_slot);
+		hpdev->pci_slot = NULL;
+	}
+}
+
 /**
  * create_root_hv_pci_bus() - Expose a new root PCI bus
  * @hbus:	Root PCI bus, as understood by this driver
@@ -2680,6 +2695,7 @@ static int hv_pci_remove(struct hv_device *hdev)
 		pci_lock_rescan_remove();
 		pci_stop_root_bus(hbus->pci_bus);
 		pci_remove_root_bus(hbus->pci_bus);
+		hv_pci_remove_slots(hbus);
 		pci_unlock_rescan_remove();
 		hbus->state = hv_pcibus_removed;
 	}
-- 
2.19.1