Re: [libvirt] [PATCH 2/2]: Call udevsettle in the appropriate places

Instead of relying solely on polling for /dev devices to appear in libvirt, we really should be synchronizing against udev. This is generally done by a call to udevsettle, which is exactly what this patch implements for the storage backends that are likely to create new /dev nodes. I believe I've read that even after udevsettle, you are not guaranteed that devices are all the way created, so we still need the polling in the rest of the sources, but this should give us a much better chance of things existing as we expect. Signed-off-by: Chris Lalancette <clalance(a)redhat.com&gt;

Index: src/storage_backend.c =================================================================== RCS file: /data/cvs/libvirt/src/storage_backend.c,v retrieving revision 1.29 diff -u -r1.29 storage_backend.c --- a/src/storage_backend.c 17 Nov 2008 11:19:33 -0000 1.29 +++ b/src/storage_backend.c 26 Nov 2008 12:40:19 -0000 @@ -270,6 +270,20 @@ return 0; } +void virStorageBackendWaitForDevices(virConnectPtr conn) +{ + const char *const settleprog[] = { UDEVSETTLE, NULL }; + int exitstatus; + + /* + * NOTE: we ignore errors here; this is just to make sure that any device + * nodes that are being created finish before we try to + * scan them. If this fails (udevsettle exits badly, or doesn't exist + * at all), then we still have a fallback mechanism anyway. + */ + virRun(conn, settleprog, &exitstatus); +}

Index: configure.in =================================================================== RCS file: /data/cvs/libvirt/configure.in,v retrieving revision 1.187 diff -u -r1.187 configure.in --- a/configure.in 25 Nov 2008 15:48:11 -0000 1.187 +++ b/configure.in 26 Nov 2008 12:40:19 -0000 @@ -115,11 +115,15 @@ [/sbin:/usr/sbin:/usr/local/sbin:$PATH]) AC_PATH_PROG([BRCTL], [brctl], [brctl], [/sbin:/usr/sbin:/usr/local/sbin:$PATH]) +AC_PATH_PROG([UDEVSETTLE], [udevsettle], [udevsettle], + [/sbin:/usr/sbin:/usr/local/sbin:$PATH])