igb_uio: fix possible mmap failure with Linux 4.5

mmap the iomem range of the PCI device fails for kernels that
enabled CONFIG_IO_STRICT_DEVMEM option:

EAL: pci_map_resource():
         cannot mmap(39, 0x7f1c51800000, 0x100000, 0x0):
         Invalid argument (0xffffffffffffffff)

CONFIG_IO_STRICT_DEVMEM is introduced in Linux v4.5 and not enabled
by default:
Linux commit: 90a545e restrict /dev/mem to idle io memory ranges

As a workaround igb_uio can stop reserving PCI memory resources, from
kernel point of view iomem region looks like idle and mmap works
again. This matches uio_pci_generic usage.

With this update device iomem range is not protected against any
other kernel drivers or userspace access. But this  shouldn't
be a problem for dpdk usage module since purpose of the igb_uio
module is to provide userspace access.

Fixes: af75078fece3 ("first public release")

Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>

diff --git a/doc/guides/rel_notes/release_16_07.rst b/doc/guides/rel_notes/release_16_07.rst
index 569f562..e2af147 100644 (file)
--- a/doc/guides/rel_notes/release_16_07.rst
+++ b/doc/guides/rel_notes/release_16_07.rst
@@ -195,6 +195,21 @@ Resolved Issues
 EAL
 ~~~
 
+* **igb_uio: Fixed possible mmap failure for Linux >= 4.5.**
+
+  mmaping the iomem range of the PCI device fails for kernels that
+  enabled CONFIG_IO_STRICT_DEVMEM option:
+
+  EAL: pci_map_resource():
+           cannot mmap(39, 0x7f1c51800000, 0x100000, 0x0):
+           Invalid argument (0xffffffffffffffff)
+
+  CONFIG_IO_STRICT_DEVMEM is introduced in Linux v4.5
+
+  Updated igb_uio to stop reserving PCI memory resources, from
+  kernel point of view iomem region looks like idle and mmap worked
+  again. This matches uio_pci_generic usage.
+
 
 Drivers
 ~~~~~~~

diff --git a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
index 45a5720..df41e45 100644 (file)
--- a/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
+++ b/lib/librte_eal/linuxapp/igb_uio/igb_uio.c
@@ -342,16 +342,6 @@ igbuio_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
                goto fail_free;
        }
 
-       /*
-        * reserve device's PCI memory regions for use by this
-        * module
-        */
-       err = pci_request_regions(dev, "igb_uio");
-       if (err != 0) {
-               dev_err(&dev->dev, "Cannot request regions\n");
-               goto fail_disable;
-       }
-
        /* enable bus mastering on the device */
        pci_set_master(dev);
 
@@ -441,8 +431,6 @@ fail_release_iomem:
        igbuio_pci_release_iomem(&udev->info);
        if (udev->mode == RTE_INTR_MODE_MSIX)
                pci_disable_msix(udev->pdev);
-       pci_release_regions(dev);
-fail_disable:
        pci_disable_device(dev);
 fail_free:
        kfree(udev);
@@ -460,7 +448,6 @@ igbuio_pci_remove(struct pci_dev *dev)
        igbuio_pci_release_iomem(&udev->info);
        if (udev->mode == RTE_INTR_MODE_MSIX)
                pci_disable_msix(dev);
-       pci_release_regions(dev);
        pci_disable_device(dev);
        pci_set_drvdata(dev, NULL);
        kfree(udev);