runqemu: keep generating tap devices

in case there is no tap device the script tries to
generate a new one.
The new device is then unguarded for a moment, so
the newly generated device could be acquired
by a different instance or user, before it is locked to
the instance with acquire_taplock.
To fix that keep generating new tap devices in case
the lock can't be acquired up to 5 times.
If no tap device can be locked it fails in the existing
error handling

(From OE-Core rev: ae4e4fb703f63402cacbef772e70082e5760f78a)

Signed-off-by: Konrad Weihmann <kweihmann@outlook.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 23876576d054ebbab9b02c0012782aa56feda123)
Signed-off-by: Steve Sakoman <steve@sakoman.com>

1 files changed, 14 insertions, 10 deletions

diff --git a/scripts/runqemu b/scripts/runqemu
index 69cd44864e..fe395d1bc6 100755
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -1195,16 +1195,20 @@ to your build configuration.
             uid = os.getuid()
             logger.info("Setting up tap interface under sudo")
             cmd = ('sudo', self.qemuifup, str(gid))
-            try:
-                tap = subprocess.check_output(cmd).decode('utf-8').strip()
-            except subprocess.CalledProcessError as e:
-                logger.error('Setting up tap device failed:\n%s\nRun runqemu-gen-tapdevs to manually create one.' % str(e))
-                sys.exit(1)
-            lockfile = os.path.join(lockdir, tap)
-            self.taplock = lockfile + '.lock'
-            self.acquire_taplock()
-            self.cleantap = True
-            logger.debug('Created tap: %s' % tap)
+            for _ in range(5):
+                try:
+                    tap = subprocess.check_output(cmd).decode('utf-8').strip()
+                except subprocess.CalledProcessError as e:
+                    logger.error('Setting up tap device failed:\n%s\nRun runqemu-gen-tapdevs to manually create one.' % str(e))
+                    sys.exit(1)
+                lockfile = os.path.join(lockdir, tap)
+                self.taplock = lockfile + '.lock'
+                if self.acquire_taplock():
+                    self.cleantap = True
+                    logger.debug('Created tap: %s' % tap)
+                    break
+                else:
+                    tap = None
 
         if not tap:
             logger.error("Failed to setup tap device. Run runqemu-gen-tapdevs to manually create.")