igb_uio: allow multi-process access

In some case, one device are accessed by different processes via
different BARs, so one uio device may be opened by more than one
process, for this case we just need to enable interrupt once, and
pci_clear_master only when the last process closed.

Fixes: 5f6ff30dc507 ("igb_uio: fix interrupt enablement after FLR in VM")
Cc: stable@dpdk.org
Signed-off-by: Xiao Wang <xiao.w.wang@intel.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>

diff --git a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
index 7f2b4c8..9f0fb5e 100644 (file)
--- a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
+++ b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
@@ -26,6 +26,8 @@ struct rte_uio_pci_dev {
        struct uio_info info;
        struct pci_dev *pdev;
        enum rte_intr_mode mode;
+       struct mutex lock;
+       int refcnt;
 };
 
 static char *intr_mode;
@@ -317,11 +319,18 @@ igbuio_pci_open(struct uio_info *info, struct inode *inode)
        struct pci_dev *dev = udev->pdev;
        int err;
 
+       mutex_lock(&udev->lock);
+       if (++udev->refcnt > 1) {
+               mutex_unlock(&udev->lock);
+               return 0;
+       }
+
        /* set bus master, which was cleared by the reset function */
        pci_set_master(dev);
 
        /* enable interrupts */
        err = igbuio_pci_enable_interrupts(udev);
+       mutex_unlock(&udev->lock);
        if (err) {
                dev_err(&dev->dev, "Enable interrupt fails\n");
                return err;
@@ -335,12 +344,19 @@ igbuio_pci_release(struct uio_info *info, struct inode *inode)
        struct rte_uio_pci_dev *udev = info->priv;
        struct pci_dev *dev = udev->pdev;
 
+       mutex_lock(&udev->lock);
+       if (--udev->refcnt > 0) {
+               mutex_unlock(&udev->lock);
+               return 0;
+       }
+
        /* disable interrupts */
        igbuio_pci_disable_interrupts(udev);
 
        /* stop the device from further DMA */
        pci_clear_master(dev);
 
+       mutex_unlock(&udev->lock);
        return 0;
 }
 
@@ -461,6 +477,7 @@ igbuio_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
        if (!udev)
                return -ENOMEM;
 
+       mutex_init(&udev->lock);
        /*
         * enable device: ask low-level code to enable I/O and
         * memory
@@ -551,6 +568,7 @@ igbuio_pci_remove(struct pci_dev *dev)
 {
        struct rte_uio_pci_dev *udev = pci_get_drvdata(dev);
 
+       mutex_destroy(&udev->lock);
        sysfs_remove_group(&dev->dev.kobj, &dev_attr_grp);
        uio_unregister_device(&udev->info);
        igbuio_pci_release_iomem(&udev->info);