From 7a6b2ce603a44db60a3ba7a4a62ec3c04c1db656 Mon Sep 17 00:00:00 2001 From: Chen Qi Date: Fri, 12 Jul 2019 15:31:13 +0800 Subject: qemurunner.py: fix race condition at qemu startup When handling pid file, qemu would first create the file, stat it, lock it and then write actually contents to it. So it's possbile that when reading the pid file, the content is empty. [YOCTO #13390] (From OE-Core rev: 170e59b203a02f8438b9aeab3a45f6fcd6608b1f) Signed-off-by: Chen Qi Signed-off-by: Richard Purdie --- meta/lib/oeqa/utils/qemurunner.py | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/meta/lib/oeqa/utils/qemurunner.py b/meta/lib/oeqa/utils/qemurunner.py index c16227fc38..68684aeb8a 100644 --- a/meta/lib/oeqa/utils/qemurunner.py +++ b/meta/lib/oeqa/utils/qemurunner.py @@ -425,13 +425,20 @@ class QemuRunner: if not self.runqemu or self.runqemu.poll() is not None: return False if os.path.isfile(self.qemu_pidfile): - f = open(self.qemu_pidfile, 'r') - qemu_pid = f.read() - f.close() - qemupid = int(qemu_pid) - if os.path.exists("/proc/" + str(qemupid)): - self.qemupid = qemupid - return True + # when handling pidfile, qemu creates the file, stat it, lock it and then write to it + # so it's possible that the file has been created but the content is empty + pidfile_timeout = time.time() + 3 + while time.time() < pidfile_timeout: + with open(self.qemu_pidfile, 'r') as f: + qemu_pid = f.read().strip() + # file created but not yet written contents + if not qemu_pid: + time.sleep(0.5) + continue + else: + if os.path.exists("/proc/" + qemu_pid): + self.qemupid = int(qemu_pid) + return True return False def run_serial(self, command, raw=False, timeout=60): -- cgit v1.2.3-54-g00ecf