linux-kernel - [PATCH] PCI / tg3: Give up chip reset and carrier loss handling if PCI device is not present

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Message-ID: <7807315.7cU9KldDtM@vostro.rjw.lan>
Date:	Sun, 01 Dec 2013 02:34:37 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	netdev@...r.kernel.org
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Nithin Nayak Sujir <nsujir@...adcom.com>,
	Michael Chan <mchan@...adcom.com>,
	David Miller <davem@...emloft.net>
Subject: [PATCH] PCI / tg3: Give up chip reset and carrier loss handling if PCI device is not present

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Modify tg3_chip_reset() and tg3_close() to check if the PCI network
adapter device is accessible at all in order to skip poking it or
trying to handle a carrier loss in vain when that's not the case.
Introduce a special PCI helper function pci_device_is_present()
for this purpose.

Of course, this uncovers the lack of the appropriate RTNL locking
in tg3_suspend() and tg3_resume(), so add that locking in there
too.

These changes prevent tg3 from burning a CPU at 100% load level for
solid several seconds after the Thunderbolt link is disconnected from
a Matrox DS1 docking station.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/net/ethernet/broadcom/tg3.c |   26 +++++++++++++++++++-------
 drivers/pci/pci.c                   |    8 ++++++++
 include/linux/pci.h                 |    1 +
 3 files changed, 28 insertions(+), 7 deletions(-)

Index: linux-pm/drivers/net/ethernet/broadcom/tg3.c
===================================================================
--- linux-pm.orig/drivers/net/ethernet/broadcom/tg3.c
+++ linux-pm/drivers/net/ethernet/broadcom/tg3.c
@@ -8932,6 +8932,9 @@ static int tg3_chip_reset(struct tg3 *tp
 	void (*write_op)(struct tg3 *, u32, u32);
 	int i, err;
 
+	if (!pci_device_is_present(tp->pdev))
+		return -ENODEV;
+
 	tg3_nvram_lock(tp);
 
 	tg3_ape_lock(tp, TG3_APE_LOCK_GRC);
@@ -11594,10 +11597,11 @@ static int tg3_close(struct net_device *
 	memset(&tp->net_stats_prev, 0, sizeof(tp->net_stats_prev));
 	memset(&tp->estats_prev, 0, sizeof(tp->estats_prev));
 
-	tg3_power_down_prepare(tp);
-
-	tg3_carrier_off(tp);
+	if (pci_device_is_present(tp->pdev)) {
+		tg3_power_down_prepare(tp);
 
+		tg3_carrier_off(tp);
+	}
 	return 0;
 }
 
@@ -17739,10 +17743,12 @@ static int tg3_suspend(struct device *de
 	struct pci_dev *pdev = to_pci_dev(device);
 	struct net_device *dev = pci_get_drvdata(pdev);
 	struct tg3 *tp = netdev_priv(dev);
-	int err;
+	int err = 0;
+
+	rtnl_lock();
 
 	if (!netif_running(dev))
-		return 0;
+		goto unlock;
 
 	tg3_reset_task_cancel(tp);
 	tg3_phy_stop(tp);
@@ -17784,6 +17790,8 @@ out:
 			tg3_phy_start(tp);
 	}
 
+unlock:
+	rtnl_unlock();
 	return err;
 }
 
@@ -17792,10 +17800,12 @@ static int tg3_resume(struct device *dev
 	struct pci_dev *pdev = to_pci_dev(device);
 	struct net_device *dev = pci_get_drvdata(pdev);
 	struct tg3 *tp = netdev_priv(dev);
-	int err;
+	int err = 0;
+
+	rtnl_lock();
 
 	if (!netif_running(dev))
-		return 0;
+		goto unlock;
 
 	netif_device_attach(dev);
 
@@ -17819,6 +17829,8 @@ out:
 	if (!err)
 		tg3_phy_start(tp);
 
+unlock:
+	rtnl_unlock();
 	return err;
 }
 #endif /* CONFIG_PM_SLEEP */
Index: linux-pm/drivers/pci/pci.c
===================================================================
--- linux-pm.orig/drivers/pci/pci.c
+++ linux-pm/drivers/pci/pci.c
@@ -4171,6 +4171,14 @@ int pci_set_vga_state(struct pci_dev *de
 	return 0;
 }
 
+bool pci_device_is_present(struct pci_dev *pdev)
+{
+	u32 v;
+
+	return pci_bus_read_dev_vendor_id(pdev->bus, pdev->devfn, &v, 0);
+}
+EXPORT_SYMBOL_GPL(pci_device_is_present);
+
 #define RESOURCE_ALIGNMENT_PARAM_SIZE COMMAND_LINE_SIZE
 static char resource_alignment_param[RESOURCE_ALIGNMENT_PARAM_SIZE] = {0};
 static DEFINE_SPINLOCK(resource_alignment_lock);
Index: linux-pm/include/linux/pci.h
===================================================================
--- linux-pm.orig/include/linux/pci.h
+++ linux-pm/include/linux/pci.h
@@ -961,6 +961,7 @@ void pci_update_resource(struct pci_dev
 int __must_check pci_assign_resource(struct pci_dev *dev, int i);
 int __must_check pci_reassign_resource(struct pci_dev *dev, int i, resource_size_t add_size, resource_size_t align);
 int pci_select_bars(struct pci_dev *dev, unsigned long flags);
+bool pci_device_is_present(struct pci_dev *pdev);
 
 /* ROM control related routines */
 int pci_enable_rom(struct pci_dev *pdev);

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