test/py: handle exceptions in console creation

From: Stephen Warren <[email protected]>

u_boot_console.exec_attach.get_spawn() performs two steps:
1) Spawn a process to communicate with the serial console.
2) Reset the board so that U-Boot starts running from scratch.

Currently, if an exception happens in step (2), no cleanup is performed on the process created in step (1). That process stays running and may e.g. hold serial port locks, or simply continue to read data from the serial port, thus preventing it from reaching any other process that attempts to read from the same serial port later. While there is error cleanup code in u_boot_console_base.ensure_spawned(), this is not triggered since the exception prevents assignment to self.p there, and hence the exception handler has no object to operate upon in cleanup_spawn().

Solve this by enhancing u_boot_console.exec_attach.get_spawn() to clean up any objects it has created.

In theory, u_boot_spawn.Spawn's constructor has a similar issue, so fix this too.

Signed-off-by Stephen Warren <[email protected]>

---
 test/py/u_boot_console_exec_attach.py | 14 +++++++++-----
 test/py/u_boot_spawn.py               |  8 ++++++--
 2 files changed, 15 insertions(+), 7 deletions(-)

test/py/u_boot_console_exec_attach.py +0 -4

index 1be27c193079..445b58dda612 100644
@@ -58,10 +58,14 @@ class ConsoleExecAttach(ConsoleBase):
         args = [self.config.board_type, self.config.board_identity]
         s = Spawn(['u-boot-test-console'] + args)
 
-        self.log.action('Resetting board')
-        cmd = ['u-boot-test-reset'] + args
-        runner = self.log.get_runner(cmd[0], sys.stdout)
-        runner.run(cmd)

test/py/u_boot_console_exec_attach.py +0 -0

         return s

test/py/u_boot_spawn.py +6 -3

index 3d9cde5ee0d0..a5f4a8e91bae 100644
@@ -56,8 +56,12 @@ class Spawn(object):
             finally:
                 os._exit(255)
 
-        self.poll = select.poll()
-        self.poll.register(self.fd, select.POLLIN | select.POLLPRI | select.POLLERR | select.POLLHUP | select.POLLNVAL)
+        try:
+            self.poll = select.poll()
+            self.poll.register(self.fd, select.POLLIN | select.POLLPRI | select.POLLERR | select.POLLHUP | select.POLLNVAL)
+        except:
+            self.close()
+            raise
 
     def kill(self, sig):
         """Send unix signal "sig" to the child process.
--

2.7.0

Hi Stephen,

Quoted 18 lines · Stephen Warren

From: Stephen Warren <[email protected]>

u_boot_console.exec_attach.get_spawn() performs two steps:
1) Spawn a process to communicate with the serial console.
2) Reset the board so that U-Boot starts running from scratch.

Currently, if an exception happens in step (2), no cleanup is performed on the process created in step (1). That process stays running and may e.g. hold serial port locks, or simply continue to read data from the serial port, thus preventing it from reaching any other process that attempts to read from the same serial port later. While there is error cleanup code in u_boot_console_base.ensure_spawned(), this is not triggered since the exception prevents assignment to self.p there, and hence the exception handler has no object to operate upon in cleanup_spawn().

Solve this by enhancing u_boot_console.exec_attach.get_spawn() to clean up any objects it has created.

Quoted 9 lines

In theory, u_boot_spawn.Spawn's constructor has a similar issue, so fix this too.

Signed-off-by Stephen Warren <[email protected]>

---
 test/py/u_boot_console_exec_attach.py | 14 +++++++++-----
 test/py/u_boot_spawn.py               |  8 ++++++--
 2 files changed, 15 insertions(+), 7 deletions(-)

Acked-by Simon Glass <[email protected]>

But please see below.

Quoted 8 lines

test/py/u_boot_console_exec_attach.py +0 -0

index 1be27c193079..445b58dda612 100644
@@ -58,10 +58,14 @@ class ConsoleExecAttach(ConsoleBase):
         args = [self.config.board_type, self.config.board_identity]
         s = Spawn(['u-boot-test-console'] + args)
 

Quoted 4 lines

test/py/u_boot_console_exec_attach.py +0 -4

-        self.log.action('Resetting board')
-        cmd = ['u-boot-test-reset'] + args
-        runner = self.log.get_runner(cmd[0], sys.stdout)
-        runner.run(cmd)

test/py/u_boot_console_exec_attach.py class ConsoleExecAttach(ConsoleBase): · line 69

Quoted 10 lines

test/py/u_boot_console_exec_attach.py +9 -1

-        runner.close()
+        try:
+            self.log.action('Resetting board')
+            cmd = ['u-boot-test-reset'] + args
+            runner = self.log.get_runner(cmd[0], sys.stdout)
+            runner.run(cmd)
+            runner.close()
+        except:
+            s.close()
+            raise

Would try...finally work here? It might avoid the 'raise'.

From: Stephen Warren <[email protected]>

u_boot_console.exec_attach.get_spawn() performs two steps:
1) Spawn a process to communicate with the serial console.
2) Reset the board so that U-Boot starts running from scratch.

Currently, if an exception happens in step (2), no cleanup is performed on the process created in step (1). That process stays running and may e.g. hold serial port locks, or simply continue to read data from the serial port, thus preventing it from reaching any other process that attempts to read from the same serial port later. While there is error cleanup code in u_boot_console_base.ensure_spawned(), this is not triggered since the exception prevents assignment to self.p there, and hence the exception handler has no object to operate upon in cleanup_spawn().

Solve this by enhancing u_boot_console.exec_attach.get_spawn() to clean up any objects it has created.

In theory, u_boot_spawn.Spawn's constructor has a similar issue, so fix this too.

Signed-off-by Stephen Warren <[email protected]>

Acked-by Simon Glass <[email protected]>