linux-kernel - [PATCH 02/18] thunderbolt: Serialize PCIe tunnel creation with PCI rescan

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Date:   Tue, 13 Feb 2018 20:00:02 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     linux-kernel@...r.kernel.org
Cc:     Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <yehezkel.bernat@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Mario.Limonciello@...l.com,
        Radion Mirchevsky <radion.mirchevsky@...el.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH 02/18] thunderbolt: Serialize PCIe tunnel creation with PCI rescan

We need to make sure a new PCIe tunnel is not created in a middle of
previous PCI rescan because otherwise the rescan code might find too
much and fail to reconfigure devices properly. This is important when
native PCIe hotplug is used. In BIOS assisted hotplug there should be no
such issue.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/thunderbolt/switch.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index da54ace4dd2f..1cc79785ce42 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -716,6 +716,13 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
 	if (sw->authorized)
 		goto unlock;
 
+	/*
+	 * Make sure there is no PCIe rescan ongoing when a new PCIe
+	 * tunnel is created. Otherwise the PCIe rescan code might find
+	 * the new tunnel too early.
+	 */
+	pci_lock_rescan_remove();
+
 	switch (val) {
 	/* Approve switch */
 	case 1:
@@ -735,6 +742,8 @@ static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
 		break;
 	}
 
+	pci_unlock_rescan_remove();
+
 	if (!ret) {
 		sw->authorized = val;
 		/* Notify status change to the userspace */
-- 
2.15.1