From: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Subject: [PATCH] do not use drmGetBusid to grab the pci-id name

The kernel returns EACCES or EAGAIN on drm open when the drm device is
currently unavailable, such as if it is in use by another process
(e.g. plymouth), or hasn't finished initializing (e.g. on a really fast
SSD). Because the probing is done before a vt switch is completed,
we have no way to ensure that we can own DRM master. This results
in failing to boot.

Also attrib->unowned is not initialized, always initialize it to fix
a valgrind warning, and to prevent adding the same device a second time
after a vt switch.

Fixes: https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/982889

Signed-off-by: Bryce Harrington <bryce@canonical.com>
---
 hw/xfree86/os-support/linux/lnx_platform.c |   29 +++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

--- a/config/udev.c
+++ b/config/udev.c
@@ -98,7 +98,7 @@
         if (strncmp(sysname, "card", 4) != 0)
             return;
 
-        LogMessage(X_INFO, "config/udev: Adding drm device (%s)\n", path);
+        LogMessage(X_INFO, "config/udev: Adding drm device (%s) %s %s\n", path, sysname, syspath);
 
         config_udev_odev_setup_attribs(path, syspath, NewGPUDeviceRequest);
         return;
@@ -430,11 +430,23 @@
 #ifdef CONFIG_UDEV_KMS
 
 static Bool
+get_pci_busid(const char *in, char *pci_str)
+{
+    int ret, domain, bus, dev, func;
+    ret = sscanf(in, "/%04x:%02x:%02x.%d/drm/card%*d", &domain, &bus, &dev, &func);
+    if (ret != 4)
+        return FALSE;
+    sprintf(pci_str, "pci:%04x:%02x:%02x.%d", domain, bus, dev, func);
+    return TRUE;
+}
+
+static Bool
 config_udev_odev_setup_attribs(const char *path, const char *syspath,
                                config_odev_probe_proc_ptr probe_callback)
 {
     struct OdevAttributes *attribs = config_odev_allocate_attribute_list();
     int ret;
+    const char *platform;
 
     if (!attribs)
         return FALSE;
@@ -447,6 +459,33 @@
     if (ret == FALSE)
         goto fail;
 
+    if (strstr(syspath, "/devices/pci")) {
+        char pci_str[17];
+        const char *end = strstr(syspath, "/drm/card");
+        if (strstr(syspath, "/usb"))
+            ret = config_odev_add_attribute(attribs, ODEV_ATTRIB_BUSID, "");
+        else if (get_pci_busid(end - 13, pci_str))
+            ret = config_odev_add_attribute(attribs, ODEV_ATTRIB_BUSID, pci_str);
+    } else if ((platform = strstr(syspath, "/devices/platform/"))) {
+        /* OMAP relies on this, modesetting doesn't use it */
+        const char *end;
+        platform += 18;
+        end = strchr(platform, '.');
+        if (end) {
+            char *busid;
+            ret = asprintf(&busid, "platform:%.*s:%02li",
+                           (int)(end - platform), platform, strtol(end + 1, NULL, 10));
+            if (ret >= 0) {
+                ret = config_odev_add_attribute(attribs, ODEV_ATTRIB_BUSID, busid);
+                free(busid);
+            }
+            else
+                ret = TRUE;
+        }
+    }
+    if (ret == FALSE)
+        goto fail;
+
     /* ownership of attribs is passed to probe layer */
     probe_callback(attribs);
     return TRUE;
--- a/hw/xfree86/os-support/linux/lnx_platform.c
+++ b/hw/xfree86/os-support/linux/lnx_platform.c
@@ -19,44 +19,6 @@
 
 #include "hotplug.h"
 
-static Bool
-get_drm_info(struct OdevAttributes *attribs, char *path, int delayed_index)
-{
-    drmSetVersion sv;
-    char *buf;
-    int fd;
-    int err = 0;
-
-    fd = open(path, O_RDWR, O_CLOEXEC);
-    if (fd == -1)
-        return FALSE;
-
-    sv.drm_di_major = 1;
-    sv.drm_di_minor = 4;
-    sv.drm_dd_major = -1;       /* Don't care */
-    sv.drm_dd_minor = -1;       /* Don't care */
-
-    err = drmSetInterfaceVersion(fd, &sv);
-    if (err) {
-        ErrorF("setversion 1.4 failed: %s\n", strerror(-err));
-	goto out;
-    }
-
-    /* for a delayed probe we've already added the device */
-    if (delayed_index == -1) {
-            xf86_add_platform_device(attribs);
-            delayed_index = xf86_num_platform_devices - 1;
-    }
-
-    buf = drmGetBusid(fd);
-    xf86_add_platform_device_attrib(delayed_index,
-                                    ODEV_ATTRIB_BUSID, buf);
-    drmFreeBusid(buf);
-out:
-    close(fd);
-    return (err == 0);
-}
-
 Bool
 xf86PlatformDeviceCheckBusID(struct xf86_platform_device *device, const char *busid)
 {
@@ -105,11 +67,6 @@
     char *dpath;
     dpath = xf86_get_platform_attrib(index, ODEV_ATTRIB_PATH);
 
-    ret = get_drm_info(attribs, dpath, index);
-    if (ret == FALSE) {
-        xf86_remove_platform_device(index);
-        return;
-    }
     ret = xf86platformAddDevice(index);
     if (ret == -1)
         xf86_remove_platform_device(index);
@@ -145,18 +102,10 @@
 
     LogMessage(X_INFO, "xfree86: Adding drm device (%s)\n", path);
 
-    if (!xf86VTOwner()) {
-            /* if we don't currently own the VT then don't probe the device,
-               just mark it as unowned for later use */
-            attribs->unowned = TRUE;
-            xf86_add_platform_device(attribs);
-            return;
-    }
-
-    ret = get_drm_info(attribs, path, -1);
-    if (ret == FALSE)
-        goto out_free;
-
+    /* if we don't currently own the VT then don't probe the device,
+       just mark it as unowned for later use */
+    attribs->unowned = !xf86VTOwner();
+    xf86_add_platform_device(attribs);
     return;
 
 out_free: