[dpdk-dev] [PATCH v4] igb_uio: fix possible mmap failure for Linux >= v4.5

[Ferruh Yigit]

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 at intel.com>

---
v4:
*  release notes, resolved issues section updated for this fix
---
 doc/guides/rel_notes/release_16_07.rst    | 14 ++++++++++++++
 lib/librte_eal/linuxapp/igb_uio/igb_uio.c | 13 -------------
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/doc/guides/rel_notes/release_16_07.rst b/doc/guides/rel_notes/release_16_07.rst
index 569f562..1ddcdab 100644
--- a/doc/guides/rel_notes/release_16_07.rst
+++ b/doc/guides/rel_notes/release_16_07.rst
@@ -231,6 +231,20 @@ Examples
 Other
 ~~~~~
 
+* **igb_uio: Fixed possible mmap failure for Linux >= v4.5.**
+
+    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.
 
 Known Issues
 ------------
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
--- 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);
-- 
2.7.4