tools: assume that special Xen devices have been created by the platform

Remove all the magic surrounding the special Xen devices in Linux
specific code whereby we attempt to figure out what the correct
major:minor number is and check the the existing device has these
numbers etc. In 2010 we really should be able to trust that the
platform has created the devices correctly or provide correct
configuration settings such that they are without resorting to tearing
down the platform configured state and rebuilding it.

tools/hotplug/Linux/xen-backend.rules already contains the necessary
udev rules to create /dev/xen/evtchn and friends in the correct place.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 3 insertions, 118 deletions

diff --git a/tools/libxc/xc_linux.c b/tools/libxc/xc_linux.c
index 4c1498f2ae..883a70e7cb 100644
--- a/tools/libxc/xc_linux.c
+++ b/tools/libxc/xc_linux.c
@@ -316,126 +316,11 @@ int do_xen_hypercall(xc_interface *xch, privcmd_hypercall_t *hypercall)
                       (unsigned long)hypercall);
 }
 
-#define MTAB "/proc/mounts"
-#define MAX_PATH 255
-#define _STR(x) #x
-#define STR(x) _STR(x)
-
-static int find_sysfsdir(char *sysfsdir)
-{
-    FILE *fp;
-    char type[MAX_PATH + 1];
-
-    if ( (fp = fopen(MTAB, "r")) == NULL )
-        return -1;
-
-    while ( fscanf(fp, "%*s %"STR(MAX_PATH)"s %"STR(MAX_PATH)"s %*s %*d %*d\n",
-                   sysfsdir, type) == 2 )
-        if ( strncmp(type, "sysfs", 5) == 0 )
-            break;
-
-    fclose(fp);
-
-    return ((strncmp(type, "sysfs", 5) == 0) ? 0 : -1);
-}
-
-int xc_find_device_number(const char *name)
-{
-    FILE *fp;
-    int i, major, minor;
-    char sysfsdir[MAX_PATH + 1];
-    static char *classlist[] = { "xen", "misc" };
-
-    for ( i = 0; i < (sizeof(classlist) / sizeof(classlist[0])); i++ )
-    {
-        if ( find_sysfsdir(sysfsdir) < 0 )
-            goto not_found;
-
-        /* <base>/class/<classname>/<devname>/dev */
-        strncat(sysfsdir, "/class/", MAX_PATH);
-        strncat(sysfsdir, classlist[i], MAX_PATH);
-        strncat(sysfsdir, "/", MAX_PATH);
-        strncat(sysfsdir, name, MAX_PATH);
-        strncat(sysfsdir, "/dev", MAX_PATH);
-
-        if ( (fp = fopen(sysfsdir, "r")) != NULL )
-            goto found;
-    }
-
- not_found:
-    errno = -ENOENT;
-    return -1;
-
- found:
-    if ( fscanf(fp, "%d:%d", &major, &minor) != 2 )
-    {
-        fclose(fp);
-        goto not_found;
-    }
-
-    fclose(fp);
-
-    return makedev(major, minor);
-}
-
-#define DEVXEN "/dev/xen"
-
-static int make_dev_xen(void)
-{
-    if ( mkdir(DEVXEN, 0755) != 0 )
-    {
-        struct stat st;
-        if ( (stat(DEVXEN, &st) != 0) || !S_ISDIR(st.st_mode) )
-            return -1;
-    }
-
-    return 0;
-}
-
-static int xendev_open(const char *dev)
-{
-    int fd, devnum;
-    struct stat st;
-    char *devname, *devpath;
-
-    devname = devpath = NULL;
-    fd = -1;
-
-    if ( asprintf(&devname, "xen!%s", dev) == 0 )
-        goto fail;
-
-    if ( asprintf(&devpath, "%s/%s", DEVXEN, dev) == 0 )
-        goto fail;
-
-    devnum = xc_find_device_number(dev);
-    if ( devnum == -1 )
-        devnum = xc_find_device_number(devname);
-
-    /*
-     * If we know what the correct device is and the path doesn't exist or 
-     * isn't a device, then remove it so we can create the device.
-     */
-    if ( (devnum != -1) &&
-         ((stat(devpath, &st) != 0) || !S_ISCHR(st.st_mode)) )
-    {
-        unlink(devpath);
-        if ( (make_dev_xen() == -1) ||
-             (mknod(devpath, S_IFCHR|0600, devnum) != 0) )
-            goto fail;
-    }
-
-    fd = open(devpath, O_RDWR);
-
- fail:
-    free(devname);
-    free(devpath);
-
-    return fd;
-}
+#define DEVXEN "/dev/xen/"
 
 int xc_evtchn_open(void)
 {
-    return xendev_open("evtchn");
+    return open(DEVXEN "evtchn", O_RDWR);
 }
 
 int xc_evtchn_close(int xce_handle)
@@ -551,7 +436,7 @@ void discard_file_cache(xc_interface *xch, int fd, int flush)
 
 int xc_gnttab_open(xc_interface *xch)
 {
-    return xendev_open("gntdev");
+    return open(DEVXEN "gntdev", O_RDWR);
 }
 
 int xc_gnttab_close(xc_interface *xch, int xcg_handle)