[dpdk-dev] [PATCH v9 7/7] igb_uio: fix unexpected remove issue for hotplug

[Jeff Guo]

When device be hotplug out, the pci resource will be released in kernel,
the uio fd will disappear, and the irq will be released. At this time,
if igb uio driver still try to access or release these resource, it will
cause kernel crash.

On the other hand, uio_remove will be called unexpectedly before
uio_release. The uio_remove procedure will free resources which are needed
by uio_release. So there is no chance to disable interrupt which is defined
inside uio_release procedure. This will affect later usage of interrupt.

So the case of unexpectedly removal by hot unplug should be identify and
correspondingly processed.

This patch propose to add enum rte_udev_state in struct rte_uio_pci_dev,
that will keep the state of uio device as probed/opened/released/removed.

This patch also checks kobject’s remove_uevent_sent state to detect the
unexpectedly removal status which means hot unplug. Once hot unplug be
detected, it will call uio_release as soon as possible and set the uio
status to be “removed”. After that, uio will check this status in
uio_release function, if uio have already been removed, it will only free
the dirty uio resource.

Signed-off-by: Jeff Guo <jia.guo at intel.com>
---
v9->v8:
refine commit log to be more readable.
---
 kernel/linux/igb_uio/igb_uio.c | 69 +++++++++++++++++++++++++++++++++---------
 1 file changed, 55 insertions(+), 14 deletions(-)

diff --git a/kernel/linux/igb_uio/igb_uio.c b/kernel/linux/igb_uio/igb_uio.c
index 3398eac..d126371 100644
--- a/kernel/linux/igb_uio/igb_uio.c
+++ b/kernel/linux/igb_uio/igb_uio.c
@@ -19,6 +19,14 @@
 
 #include "compat.h"
 
+/* uio pci device state */
+enum rte_udev_state {
+	RTE_UDEV_PROBED,
+	RTE_UDEV_OPENNED,
+	RTE_UDEV_RELEASED,
+	RTE_UDEV_REMOVED,
+};
+
 /**
  * A structure describing the private information for a uio device.
  */
@@ -28,6 +36,7 @@ struct rte_uio_pci_dev {
 	enum rte_intr_mode mode;
 	struct mutex lock;
 	int refcnt;
+	enum rte_udev_state state;
 };
 
 static int wc_activate;
@@ -309,6 +318,17 @@ igbuio_pci_disable_interrupts(struct rte_uio_pci_dev *udev)
 #endif
 }
 
+/* Unmap previously ioremap'd resources */
+static void
+igbuio_pci_release_iomem(struct uio_info *info)
+{
+	int i;
+
+	for (i = 0; i < MAX_UIO_MAPS; i++) {
+		if (info->mem[i].internal_addr)
+			iounmap(info->mem[i].internal_addr);
+	}
+}
 
 /**
  * This gets called while opening uio device file.
@@ -331,20 +351,35 @@ igbuio_pci_open(struct uio_info *info, struct inode *inode)
 
 	/* enable interrupts */
 	err = igbuio_pci_enable_interrupts(udev);
-	mutex_unlock(&udev->lock);
 	if (err) {
 		dev_err(&dev->dev, "Enable interrupt fails\n");
+		pci_clear_master(dev);
+		mutex_unlock(&udev->lock);
 		return err;
 	}
+	udev->state = RTE_UDEV_OPENNED;
+	mutex_unlock(&udev->lock);
 	return 0;
 }
 
+/**
+ * This gets called while closing uio device file.
+ */
 static int
 igbuio_pci_release(struct uio_info *info, struct inode *inode)
 {
 	struct rte_uio_pci_dev *udev = info->priv;
 	struct pci_dev *dev = udev->pdev;
 
+	if (udev->state == RTE_UDEV_REMOVED) {
+		mutex_destroy(&udev->lock);
+		igbuio_pci_release_iomem(&udev->info);
+		pci_disable_device(dev);
+		pci_set_drvdata(dev, NULL);
+		kfree(udev);
+		return 0;
+	}
+
 	mutex_lock(&udev->lock);
 	if (--udev->refcnt > 0) {
 		mutex_unlock(&udev->lock);
@@ -356,7 +391,7 @@ igbuio_pci_release(struct uio_info *info, struct inode *inode)
 
 	/* stop the device from further DMA */
 	pci_clear_master(dev);
-
+	udev->state = RTE_UDEV_RELEASED;
 	mutex_unlock(&udev->lock);
 	return 0;
 }
@@ -414,18 +449,6 @@ igbuio_pci_setup_ioport(struct pci_dev *dev, struct uio_info *info,
 	return 0;
 }
 
-/* Unmap previously ioremap'd resources */
-static void
-igbuio_pci_release_iomem(struct uio_info *info)
-{
-	int i;
-
-	for (i = 0; i < MAX_UIO_MAPS; i++) {
-		if (info->mem[i].internal_addr)
-			iounmap(info->mem[i].internal_addr);
-	}
-}
-
 static int
 igbuio_setup_bars(struct pci_dev *dev, struct uio_info *info)
 {
@@ -562,6 +585,9 @@ igbuio_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
 			 (unsigned long long)map_dma_addr, map_addr);
 	}
 
+	mutex_lock(&udev->lock);
+	udev->state = RTE_UDEV_PROBED;
+	mutex_unlock(&udev->lock);
 	return 0;
 
 fail_remove_group:
@@ -579,6 +605,21 @@ static void
 igbuio_pci_remove(struct pci_dev *dev)
 {
 	struct rte_uio_pci_dev *udev = pci_get_drvdata(dev);
+	struct pci_dev *pdev = udev->pdev;
+	int ret;
+
+	/* handle unexpected removal */
+	if (udev->state == RTE_UDEV_OPENNED ||
+	    (&pdev->dev.kobj)->state_remove_uevent_sent == 1) {
+		dev_notice(&dev->dev, "Unexpected removal!\n");
+		ret = igbuio_pci_release(&udev->info, NULL);
+		if (ret)
+			return;
+		mutex_lock(&udev->lock);
+		udev->state = RTE_UDEV_REMOVED;
+		mutex_unlock(&udev->lock);
+		return;
+	}
 
 	mutex_destroy(&udev->lock);
 	sysfs_remove_group(&dev->dev.kobj, &dev_attr_grp);
-- 
2.7.4