[U-Boot] [PATCH] test/py: handle exceptions in console creation

[U-Boot] [PATCH] test/py: handle exceptions in console creation

[Stephen Warren]

From: Stephen Warren <swarren@nvidia.com>

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 <swarren@nvidia.com>
---
 test/py/u_boot_console_exec_attach.py | 14 +++++++++-----
 test/py/u_boot_spawn.py               |  8 ++++++--
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/test/py/u_boot_console_exec_attach.py b/test/py/u_boot_console_exec_attach.py
index 1be27c193079..445b58dda612 100644
--- a/test/py/u_boot_console_exec_attach.py
+++ b/test/py/u_boot_console_exec_attach.py
@@ -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)
-        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
 
         return s
diff --git a/test/py/u_boot_spawn.py b/test/py/u_boot_spawn.py
index 3d9cde5ee0d0..a5f4a8e91bae 100644
--- a/test/py/u_boot_spawn.py
+++ b/test/py/u_boot_spawn.py
@@ -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

[U-Boot] [PATCH] test/py: handle exceptions in console creation

[Simon Glass]

Hi Stephen,

On 10 February 2016 at 16:54, Stephen Warren <swarren@wwwdotorg.org> wrote:
> From: Stephen Warren <swarren@nvidia.com>
>
> 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 <swarren@nvidia.com>
> ---
>  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 <sjg@chromium.org>

But please see below.

> diff --git a/test/py/u_boot_console_exec_attach.py b/test/py/u_boot_console_exec_attach.py
> index 1be27c193079..445b58dda612 100644
> --- a/test/py/u_boot_console_exec_attach.py
> +++ b/test/py/u_boot_console_exec_attach.py
> @@ -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)
> -        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'.

>
>          return s
> diff --git a/test/py/u_boot_spawn.py b/test/py/u_boot_spawn.py
> index 3d9cde5ee0d0..a5f4a8e91bae 100644
> --- a/test/py/u_boot_spawn.py
> +++ b/test/py/u_boot_spawn.py
> @@ -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
>

[U-Boot] [PATCH] test/py: handle exceptions in console creation

[Stephen Warren]

On 02/14/2016 06:19 PM, Simon Glass wrote:
> Hi Stephen,
> 
> On 10 February 2016 at 16:54, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> From: Stephen Warren <swarren@nvidia.com>
>>
>> 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 <swarren@nvidia.com>
>> ---
>>  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 <sjg@chromium.org>
> 
> But please see below.
> 
>> diff --git a/test/py/u_boot_console_exec_attach.py b/test/py/u_boot_console_exec_attach.py
>> index 1be27c193079..445b58dda612 100644
>> --- a/test/py/u_boot_console_exec_attach.py
>> +++ b/test/py/u_boot_console_exec_attach.py
>> @@ -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)
>> -        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'.

In the non-error case, s is returned later in the function and continues
to be used by the caller. So, we don't want to tear it down except when
an exception occurred.

[U-Boot] test/py: handle exceptions in console creation

[Tom Rini]

On Wed, Feb 10, 2016 at 04:54:37PM -0700, Stephen Warren wrote:

> From: Stephen Warren <swarren@nvidia.com>
> 
> 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 <swarren@nvidia.com>
> Acked-by: Simon Glass <sjg@chromium.org>

Applied to u-boot/master, thanks!

-- 
Tom
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