[OE-core] [PATCHv4 1/3] runqemu: Allow to store more than one lock for network interfaces

[Aníbal Limón]

In order to support multiple tap devices in the same qemu virtual
machine.

Signed-off-by: Aníbal Limón <anibal.limon at linaro.org>
---
 scripts/runqemu | 50 +++++++++++++++++++++++++------------------------
 1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/scripts/runqemu b/scripts/runqemu
index 4079f2b17d..38dd1c30d9 100755
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -181,8 +181,7 @@ class BaseConfig(object):
         self.audio_enabled = False
         self.tcpserial_portnum = ''
         self.custombiosdir = ''
-        self.lock = ''
-        self.lock_descriptor = None
+        self.lock_descriptors = {}
         self.bitbake_e = ''
         self.snapshot = False
         self.wictypes = ('wic', 'wic.vmdk', 'wic.qcow2', 'wic.vdi')
@@ -204,30 +203,32 @@ class BaseConfig(object):
         # avoid cleanup twice
         self.cleaned = False
 
-    def acquire_lock(self, error=True):
-        logger.debug("Acquiring lockfile %s..." % self.lock)
+    def acquire_lock(self, lock, error=True):
+        logger.debug("Acquiring lockfile %s..." % lock)
+        descriptor = None
         try:
-            self.lock_descriptor = open(self.lock, 'w')
-            fcntl.flock(self.lock_descriptor, fcntl.LOCK_EX|fcntl.LOCK_NB)
+            descriptor = open(lock, 'w')
+            fcntl.flock(descriptor, fcntl.LOCK_EX|fcntl.LOCK_NB)
         except Exception as e:
-            msg = "Acquiring lockfile %s failed: %s" % (self.lock, e)
+            msg = "Acquiring lockfile %s failed: %s" % (lock, e)
             if error:
                 logger.error(msg)
             else:
                 logger.info(msg)
-            if self.lock_descriptor:
-                self.lock_descriptor.close()
-                self.lock_descriptor = None
+            if descriptor:
+                descriptor.close()
+                descriptor = None
             return False
+        self.lock_descriptors[lock] = descriptor
         return True
 
-    def release_lock(self):
-        if self.lock_descriptor:
-            logger.debug("Releasing lockfile for tap device '%s'" % self.tap)
-            fcntl.flock(self.lock_descriptor, fcntl.LOCK_UN)
-            self.lock_descriptor.close()
-            os.remove(self.lock)
-            self.lock_descriptor = None
+    def release_lock(self, lock):
+        if self.lock_descriptors[lock]:
+            logger.debug("Releasing lockfile for tap device '%s'" % lock)
+            fcntl.flock(self.lock_descriptors[lock], fcntl.LOCK_UN)
+            self.lock_descriptors[lock].close()
+            os.remove(lock)
+            self.lock_descriptors[lock] = None
 
     def get(self, key):
         if key in self.d:
@@ -1016,8 +1017,8 @@ class BaseConfig(object):
             if os.path.exists('%s.skip' % lockfile):
                 logger.info('Found %s.skip, skipping %s' % (lockfile, p))
                 continue
-            self.lock = lockfile + '.lock'
-            if self.acquire_lock(error=False):
+            lock = lockfile + '.lock'
+            if self.acquire_lock(lock, error=False):
                 tap = p
                 logger.info("Using preconfigured tap device %s" % tap)
                 logger.info("If this is not intended, touch %s.skip to make runqemu skip %s." %(lockfile, tap))
@@ -1035,8 +1036,8 @@ class BaseConfig(object):
             cmd = ('sudo', self.qemuifup, str(uid), str(gid), self.bindir_native)
             tap = subprocess.check_output(cmd).decode('utf-8').strip()
             lockfile = os.path.join(lockdir, tap)
-            self.lock = lockfile + '.lock'
-            self.acquire_lock()
+            lock = lockfile + '.lock'
+            self.acquire_lock(lock)
             self.cleantap = True
             logger.debug('Created tap: %s' % tap)
 
@@ -1268,8 +1269,8 @@ class BaseConfig(object):
         cmds = shlex.split(cmd)
         logger.info('Running %s\n' % cmd)
         pass_fds = []
-        if self.lock_descriptor:
-            pass_fds = [self.lock_descriptor.fileno()]
+        if self.lock_descriptors.keys():
+            pass_fds = [self.lock_descriptors[lock].fileno() for lock in self.lock_descriptors.keys()]
         process = subprocess.Popen(cmds, stderr=subprocess.PIPE, pass_fds=pass_fds)
         self.qemupid = process.pid
         retcode = process.wait()
@@ -1291,7 +1292,8 @@ class BaseConfig(object):
             cmd = ('sudo', self.qemuifdown, self.tap, self.bindir_native)
             logger.debug('Running %s' % str(cmd))
             subprocess.check_call(cmd)
-        self.release_lock()
+        for lock in self.lock_descriptors.keys():
+            self.release_lock(lock)
 
         if self.nfs_running:
             logger.info("Shutting down the userspace NFS server...")
-- 
2.20.1