[PATCHv2] 1/3] libxc: prefer using privcmd character device

* [PATCHv2] 1/3] libxc: prefer using privcmd character device
@ 2015-11-24 20:14 Doug Goldstein
  2015-11-24 20:14 ` [PATCHv2] 2/3] update outdated header comment on privcmd.h Doug Goldstein
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: Doug Goldstein @ 2015-11-24 20:14 UTC (permalink / raw)
  To: xen-devel
  Cc: Ian Jackson, Wei Liu, Doug Goldstein, Ian Campbell, Stefano Stabellini

Prefer using the character device over the proc file if the character
device exists. This follows similar conversions of xenbus to avoid
issues with FMODE_ATOMIC_POS added in Linux 3.14 and newer.

CC: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: Ian Campbell <ian.campbell@citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
Signed-off-by: Doug Goldstein <cardoe@cardoe.com>
---
 tools/libxc/xc_linux_osdep.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/tools/libxc/xc_linux_osdep.c b/tools/libxc/xc_linux_osdep.c
index 76c55ff..c078b3d 100644
--- a/tools/libxc/xc_linux_osdep.c
+++ b/tools/libxc/xc_linux_osdep.c
@@ -46,7 +46,14 @@
 static xc_osdep_handle linux_privcmd_open(xc_interface *xch)
 {
     int flags, saved_errno;
-    int fd = open("/proc/xen/privcmd", O_RDWR);
+    int fd = open("/dev/xen/privcmd", O_RDWR); /* prefer this newer interface */
+
+    if ( fd == -1 && ( errno == ENOENT || errno == ENXIO ||
+                       errno == ENODEV || errno == EACCES ))
+    {
+        /* Fallback to /proc/xen/privcmd */
+        fd = open("/proc/xen/privcmd", O_RDWR);
+    }
 
     if ( fd == -1 )
     {
-- 
2.4.10

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