[PATCH 1/2] test/py: Use loop mounts if guestmount fails in filesystem tests

[PATCH 1/2] test/py: Use loop mounts if guestmount fails in filesystem tests

[Alper Nebi Yasak]

If guestmount isn't available on the system, filesystem test setup falls
back to using loop mounts to prepare its disk images. If guestmount is
available but fails to work, the tests are immediately skipped. Instead
of giving up on a guestmount failure, try using loop mounts as an
attempt to keep tests running.

Also stop checking if guestmount is in PATH, as trying to run a missing
guestmount can now follow the same failure codepath and fall back to
loop mounts anyway.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
---

 test/py/tests/test_fs/conftest.py | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py
index 410a675b9714..e3c461635f8e 100644
--- a/test/py/tests/test_fs/conftest.py
+++ b/test/py/tests/test_fs/conftest.py
@@ -205,24 +205,23 @@ def mount_fs(fs_type, device, mount_point):
     """
     global fuse_mounted
 
-    fuse_mounted = False
     try:
-        if tool_is_in_path('guestmount'):
-            fuse_mounted = True
-            check_call('guestmount -a %s -m /dev/sda %s'
-                % (device, mount_point), shell=True)
-        else:
-            mount_opt = 'loop,rw'
-            if re.match('fat', fs_type):
-                mount_opt += ',umask=0000'
-
-            check_call('sudo mount -o %s %s %s'
-                % (mount_opt, device, mount_point), shell=True)
-
-            # may not be effective for some file systems
-            check_call('sudo chmod a+rw %s' % mount_point, shell=True)
+        check_call('guestmount -a %s -m /dev/sda %s'
+            % (device, mount_point), shell=True)
+        fuse_mounted = True
+        return
     except CalledProcessError:
-        raise
+        fuse_mounted = False
+
+    mount_opt = 'loop,rw'
+    if re.match('fat', fs_type):
+        mount_opt += ',umask=0000'
+
+    check_call('sudo mount -o %s %s %s'
+        % (mount_opt, device, mount_point), shell=True)
+
+    # may not be effective for some file systems
+    check_call('sudo chmod a+rw %s' % mount_point, shell=True)
 
 def umount_fs(mount_point):
     """Unmount a volume.
-- 
2.32.0.rc2

[PATCH 2/2] test/py: Wait for guestmount worker to exit after running guestunmount

[Alper Nebi Yasak]

Some filesystem tests are failing when their image is prepared with
guestmount, but succeeding if loop mounts are used instead. The reason
seems to be a race condition the guestmount(1) manual page explains:

    When guestunmount(1)/fusermount(1) exits, guestmount may still be
    running and cleaning up the mountpoint.  The disk image will not be
    fully finalized.

    This means that scripts like the following have a nasty race condition:

     guestmount -a disk.img -i /mnt
     # copy things into /mnt
     guestunmount /mnt
     # immediately try to use 'disk.img' ** UNSAFE **

    The solution is to use the --pid-file option to write the guestmount
    PID to a file, then after guestunmount spin waiting for this PID to
    exit.

The Python standard library has an os.waitpid() function for waiting a
child to terminate, but it cannot wait on non-child processes. Implement
a utility function that can do this by polling the process repeatedly
for a given duration, optionally killing the process if it won't
terminate on its own. Apply the suggested solution with this utility
function, which makes the failing tests succeed again.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
---

 test/py/tests/test_fs/conftest.py | 13 ++++++++++-
 test/py/u_boot_utils.py           | 36 +++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py
index e3c461635f8e..6b1ff05a8143 100644
--- a/test/py/tests/test_fs/conftest.py
+++ b/test/py/tests/test_fs/conftest.py
@@ -8,6 +8,7 @@
 import re
 from subprocess import call, check_call, check_output, CalledProcessError
 from fstest_defs import *
+import u_boot_utils as util
 
 supported_fs_basic = ['fat16', 'fat32', 'ext4']
 supported_fs_ext = ['fat16', 'fat32']
@@ -206,7 +207,7 @@ def mount_fs(fs_type, device, mount_point):
     global fuse_mounted
 
     try:
-        check_call('guestmount -a %s -m /dev/sda %s'
+        check_call('guestmount --pid-file guestmount.pid -a %s -m /dev/sda %s'
             % (device, mount_point), shell=True)
         fuse_mounted = True
         return
@@ -235,6 +236,16 @@ def umount_fs(mount_point):
     if fuse_mounted:
         call('sync')
         call('guestunmount %s' % mount_point, shell=True)
+
+        try:
+            with open("guestmount.pid", "r") as pidfile:
+                pid = int(pidfile.read())
+            util.waitpid(pid, kill=True)
+            os.remove("guestmount.pid")
+
+        except FileNotFoundError:
+            pass
+
     else:
         call('sudo umount %s' % mount_point, shell=True)
 
diff --git a/test/py/u_boot_utils.py b/test/py/u_boot_utils.py
index 939d82eec12a..e816c7fbb6a3 100644
--- a/test/py/u_boot_utils.py
+++ b/test/py/u_boot_utils.py
@@ -8,6 +8,7 @@
 import os
 import os.path
 import pytest
+import signal
 import sys
 import time
 import re
@@ -339,3 +340,38 @@ def crc32(u_boot_console, address, count):
     assert m, 'CRC32 operation failed.'
 
     return m.group(1)
+
+def waitpid(pid, timeout=60, kill=False):
+    """Wait a process to terminate by its PID
+
+    This is an alternative to a os.waitpid(pid, 0) call that works on
+    processes that aren't children of the python process.
+
+    Args:
+        pid: PID of a running process.
+        timeout: Time in seconds to wait.
+        kill: Whether to forcibly kill the process after timeout.
+
+    Returns:
+        True, if the process ended on its own.
+        False, if the process was killed by this function.
+
+    Raises:
+        TimeoutError, if the process is still running after timeout.
+    """
+    try:
+        for _ in range(timeout):
+            os.kill(pid, 0)
+            time.sleep(1)
+
+        if kill:
+            os.kill(pid, signal.SIGKILL)
+            return False
+
+    except ProcessLookupError:
+        return True
+
+    raise TimeoutError(
+        "Process with PID {} did not terminate after {} seconds."
+        .format(pid, timeout)
+    )
-- 
2.32.0.rc2

Re: [PATCH 1/2] test/py: Use loop mounts if guestmount fails in filesystem tests

[Simon Glass]

On Fri, 4 Jun 2021 at 13:05, Alper Nebi Yasak <alpernebiyasak@gmail.com> wrote:
>
> If guestmount isn't available on the system, filesystem test setup falls
> back to using loop mounts to prepare its disk images. If guestmount is
> available but fails to work, the tests are immediately skipped. Instead
> of giving up on a guestmount failure, try using loop mounts as an
> attempt to keep tests running.
>
> Also stop checking if guestmount is in PATH, as trying to run a missing
> guestmount can now follow the same failure codepath and fall back to
> loop mounts anyway.
>
> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
> ---
>
>  test/py/tests/test_fs/conftest.py | 31 +++++++++++++++----------------
>  1 file changed, 15 insertions(+), 16 deletions(-)

https://source.denx.de/u-boot/custodians/u-boot-dm/-/jobs/282788

thoughts below

>
> diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py
> index 410a675b9714..e3c461635f8e 100644
> --- a/test/py/tests/test_fs/conftest.py
> +++ b/test/py/tests/test_fs/conftest.py
> @@ -205,24 +205,23 @@ def mount_fs(fs_type, device, mount_point):
>      """
>      global fuse_mounted
>
> -    fuse_mounted = False
>      try:
> -        if tool_is_in_path('guestmount'):
> -            fuse_mounted = True
> -            check_call('guestmount -a %s -m /dev/sda %s'
> -                % (device, mount_point), shell=True)
> -        else:
> -            mount_opt = 'loop,rw'
> -            if re.match('fat', fs_type):
> -                mount_opt += ',umask=0000'
> -
> -            check_call('sudo mount -o %s %s %s'
> -                % (mount_opt, device, mount_point), shell=True)
> -
> -            # may not be effective for some file systems
> -            check_call('sudo chmod a+rw %s' % mount_point, shell=True)
> +        check_call('guestmount -a %s -m /dev/sda %s'
> +            % (device, mount_point), shell=True)
> +        fuse_mounted = True
> +        return
>      except CalledProcessError:
> -        raise
> +        fuse_mounted = False
> +
> +    mount_opt = 'loop,rw'
> +    if re.match('fat', fs_type):

This seems ambiguous. I think you should use:

   if 'fat' in fs_type:

or

   if fs_type.startswith('fat'):

or

  if fs_type == 'fat':

so it is clear what you mean.

> +        mount_opt += ',umask=0000'
> +
> +    check_call('sudo mount -o %s %s %s'
> +        % (mount_opt, device, mount_point), shell=True)
> +
> +    # may not be effective for some file systems
> +    check_call('sudo chmod a+rw %s' % mount_point, shell=True)
>
>  def umount_fs(mount_point):
>      """Unmount a volume.
> --
> 2.32.0.rc2
>

Regards,
Simon

Re: [PATCH 2/2] test/py: Wait for guestmount worker to exit after running guestunmount

[Simon Glass]

On Fri, 4 Jun 2021 at 13:05, Alper Nebi Yasak <alpernebiyasak@gmail.com> wrote:
>
> Some filesystem tests are failing when their image is prepared with
> guestmount, but succeeding if loop mounts are used instead. The reason
> seems to be a race condition the guestmount(1) manual page explains:
>
>     When guestunmount(1)/fusermount(1) exits, guestmount may still be
>     running and cleaning up the mountpoint.  The disk image will not be
>     fully finalized.
>
>     This means that scripts like the following have a nasty race condition:
>
>      guestmount -a disk.img -i /mnt
>      # copy things into /mnt
>      guestunmount /mnt
>      # immediately try to use 'disk.img' ** UNSAFE **
>
>     The solution is to use the --pid-file option to write the guestmount
>     PID to a file, then after guestunmount spin waiting for this PID to
>     exit.
>
> The Python standard library has an os.waitpid() function for waiting a
> child to terminate, but it cannot wait on non-child processes. Implement
> a utility function that can do this by polling the process repeatedly
> for a given duration, optionally killing the process if it won't
> terminate on its own. Apply the suggested solution with this utility
> function, which makes the failing tests succeed again.
>
> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
> ---
>
>  test/py/tests/test_fs/conftest.py | 13 ++++++++++-
>  test/py/u_boot_utils.py           | 36 +++++++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+), 1 deletion(-)
>

Reviewed-by: Simon Glass <sjg@chromium.org>

> diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py
> index e3c461635f8e..6b1ff05a8143 100644
> --- a/test/py/tests/test_fs/conftest.py
> +++ b/test/py/tests/test_fs/conftest.py
> @@ -8,6 +8,7 @@
>  import re
>  from subprocess import call, check_call, check_output, CalledProcessError
>  from fstest_defs import *
> +import u_boot_utils as util
>
>  supported_fs_basic = ['fat16', 'fat32', 'ext4']
>  supported_fs_ext = ['fat16', 'fat32']
> @@ -206,7 +207,7 @@ def mount_fs(fs_type, device, mount_point):
>      global fuse_mounted
>
>      try:
> -        check_call('guestmount -a %s -m /dev/sda %s'
> +        check_call('guestmount --pid-file guestmount.pid -a %s -m /dev/sda %s'
>              % (device, mount_point), shell=True)
>          fuse_mounted = True
>          return
> @@ -235,6 +236,16 @@ def umount_fs(mount_point):
>      if fuse_mounted:
>          call('sync')

should you remove guestmount.pid first in case it is there from a
previous crash?


>          call('guestunmount %s' % mount_point, shell=True)
> +
> +        try:
> +            with open("guestmount.pid", "r") as pidfile:
> +                pid = int(pidfile.read())
> +            util.waitpid(pid, kill=True)
> +            os.remove("guestmount.pid")
> +
> +        except FileNotFoundError:
> +            pass
> +
>      else:
>          call('sudo umount %s' % mount_point, shell=True)
>
> diff --git a/test/py/u_boot_utils.py b/test/py/u_boot_utils.py
> index 939d82eec12a..e816c7fbb6a3 100644
> --- a/test/py/u_boot_utils.py
> +++ b/test/py/u_boot_utils.py
> @@ -8,6 +8,7 @@
>  import os
>  import os.path
>  import pytest
> +import signal
>  import sys
>  import time
>  import re
> @@ -339,3 +340,38 @@ def crc32(u_boot_console, address, count):
>      assert m, 'CRC32 operation failed.'
>
>      return m.group(1)
> +
> +def waitpid(pid, timeout=60, kill=False):
> +    """Wait a process to terminate by its PID
> +
> +    This is an alternative to a os.waitpid(pid, 0) call that works on
> +    processes that aren't children of the python process.
> +
> +    Args:
> +        pid: PID of a running process.
> +        timeout: Time in seconds to wait.
> +        kill: Whether to forcibly kill the process after timeout.
> +
> +    Returns:
> +        True, if the process ended on its own.
> +        False, if the process was killed by this function.
> +
> +    Raises:
> +        TimeoutError, if the process is still running after timeout.
> +    """
> +    try:
> +        for _ in range(timeout):
> +            os.kill(pid, 0)
> +            time.sleep(1)
> +
> +        if kill:
> +            os.kill(pid, signal.SIGKILL)
> +            return False
> +
> +    except ProcessLookupError:
> +        return True
> +
> +    raise TimeoutError(
> +        "Process with PID {} did not terminate after {} seconds."
> +        .format(pid, timeout)
> +    )
> --
> 2.32.0.rc2
>

Re: [PATCH 1/2] test/py: Use loop mounts if guestmount fails in filesystem tests

[Alper Nebi Yasak]

On 26/06/2021 21:29, Simon Glass wrote:
> On Fri, 4 Jun 2021 at 13:05, Alper Nebi Yasak <alpernebiyasak@gmail.com> wrote:
>>
>> If guestmount isn't available on the system, filesystem test setup falls
>> back to using loop mounts to prepare its disk images. If guestmount is
>> available but fails to work, the tests are immediately skipped. Instead
>> of giving up on a guestmount failure, try using loop mounts as an
>> attempt to keep tests running.
>>
>> Also stop checking if guestmount is in PATH, as trying to run a missing
>> guestmount can now follow the same failure codepath and fall back to
>> loop mounts anyway.
>>
>> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
>> ---
>>
>>  test/py/tests/test_fs/conftest.py | 31 +++++++++++++++----------------
>>  1 file changed, 15 insertions(+), 16 deletions(-)
> 
> https://source.denx.de/u-boot/custodians/u-boot-dm/-/jobs/282788
> 
> thoughts below

That CI run doesn't have this patch/series applied.

>>
>> diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py
>> index 410a675b9714..e3c461635f8e 100644
>> --- a/test/py/tests/test_fs/conftest.py
>> +++ b/test/py/tests/test_fs/conftest.py
>> @@ -205,24 +205,23 @@ def mount_fs(fs_type, device, mount_point):
>>      """
>>      global fuse_mounted
>>
>> -    fuse_mounted = False
>>      try:
>> -        if tool_is_in_path('guestmount'):
>> -            fuse_mounted = True
>> -            check_call('guestmount -a %s -m /dev/sda %s'
>> -                % (device, mount_point), shell=True)
>> -        else:
>> -            mount_opt = 'loop,rw'
>> -            if re.match('fat', fs_type):
>> -                mount_opt += ',umask=0000'
>> -
>> -            check_call('sudo mount -o %s %s %s'
>> -                % (mount_opt, device, mount_point), shell=True)
>> -
>> -            # may not be effective for some file systems
>> -            check_call('sudo chmod a+rw %s' % mount_point, shell=True)
>> +        check_call('guestmount -a %s -m /dev/sda %s'
>> +            % (device, mount_point), shell=True)
>> +        fuse_mounted = True
>> +        return
>>      except CalledProcessError:
>> -        raise
>> +        fuse_mounted = False
>> +
>> +    mount_opt = 'loop,rw'
>> +    if re.match('fat', fs_type):
> 
> This seems ambiguous. I think you should use:
> 
>    if 'fat' in fs_type:
> 
> or
> 
>    if fs_type.startswith('fat'):
> 
> or
> 
>   if fs_type == 'fat':
> 
> so it is clear what you mean.

This just unindents existing code. I can send v2 with startswith('fat')
though.

(I think I should rewrite the tests with guestfish and remove these
mount functions instead; but I'm busy with other things for a while.)

>> +        mount_opt += ',umask=0000'
>> +
>> +    check_call('sudo mount -o %s %s %s'
>> +        % (mount_opt, device, mount_point), shell=True)
>> +
>> +    # may not be effective for some file systems
>> +    check_call('sudo chmod a+rw %s' % mount_point, shell=True)
>>
>>  def umount_fs(mount_point):
>>      """Unmount a volume.
>> --
>> 2.32.0.rc2
>>
> 
> Regards,
> Simon
> 

Re: [PATCH 2/2] test/py: Wait for guestmount worker to exit after running guestunmount

[Alper Nebi Yasak]

On 26/06/2021 21:29, Simon Glass wrote:
> On Fri, 4 Jun 2021 at 13:05, Alper Nebi Yasak <alpernebiyasak@gmail.com> wrote:
>>
>> Some filesystem tests are failing when their image is prepared with
>> guestmount, but succeeding if loop mounts are used instead. The reason
>> seems to be a race condition the guestmount(1) manual page explains:
>>
>>     When guestunmount(1)/fusermount(1) exits, guestmount may still be
>>     running and cleaning up the mountpoint.  The disk image will not be
>>     fully finalized.
>>
>>     This means that scripts like the following have a nasty race condition:
>>
>>      guestmount -a disk.img -i /mnt
>>      # copy things into /mnt
>>      guestunmount /mnt
>>      # immediately try to use 'disk.img' ** UNSAFE **
>>
>>     The solution is to use the --pid-file option to write the guestmount
>>     PID to a file, then after guestunmount spin waiting for this PID to
>>     exit.
>>
>> The Python standard library has an os.waitpid() function for waiting a
>> child to terminate, but it cannot wait on non-child processes. Implement
>> a utility function that can do this by polling the process repeatedly
>> for a given duration, optionally killing the process if it won't
>> terminate on its own. Apply the suggested solution with this utility
>> function, which makes the failing tests succeed again.
>>
>> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
>> ---
>>
>>  test/py/tests/test_fs/conftest.py | 13 ++++++++++-
>>  test/py/u_boot_utils.py           | 36 +++++++++++++++++++++++++++++++
>>  2 files changed, 48 insertions(+), 1 deletion(-)
>>
> 
> Reviewed-by: Simon Glass <sjg@chromium.org>
> 
>> diff --git a/test/py/tests/test_fs/conftest.py b/test/py/tests/test_fs/conftest.py
>> index e3c461635f8e..6b1ff05a8143 100644
>> --- a/test/py/tests/test_fs/conftest.py
>> +++ b/test/py/tests/test_fs/conftest.py
>> @@ -8,6 +8,7 @@
>>  import re
>>  from subprocess import call, check_call, check_output, CalledProcessError
>>  from fstest_defs import *
>> +import u_boot_utils as util
>>
>>  supported_fs_basic = ['fat16', 'fat32', 'ext4']
>>  supported_fs_ext = ['fat16', 'fat32']
>> @@ -206,7 +207,7 @@ def mount_fs(fs_type, device, mount_point):
>>      global fuse_mounted
>>
>>      try:
>> -        check_call('guestmount -a %s -m /dev/sda %s'
>> +        check_call('guestmount --pid-file guestmount.pid -a %s -m /dev/sda %s'
>>              % (device, mount_point), shell=True)
>>          fuse_mounted = True
>>          return
>> @@ -235,6 +236,16 @@ def umount_fs(mount_point):
>>      if fuse_mounted:
>>          call('sync')
> 
> should you remove guestmount.pid first in case it is there from a
> previous crash?

Guestmount overwrites the pid file without complaining, and the worker
deletes the file on its own when it terminates after the guestunmount call.

I think it's OK to ignore an existing pid file if the mount point is
clean. If not clean, that's the actual problem and both guestmount and
mount will fail, causing the tests to be skipped. We could clean mount
points automatically before attempting to mount.

>>          call('guestunmount %s' % mount_point, shell=True)
>> +
>> +        try:
>> +            with open("guestmount.pid", "r") as pidfile:
>> +                pid = int(pidfile.read())
>> +            util.waitpid(pid, kill=True)
>> +            os.remove("guestmount.pid")
>> +
>> +        except FileNotFoundError:
>> +            pass
>> +
>>      else:
>>          call('sudo umount %s' % mount_point, shell=True)
>>
>> diff --git a/test/py/u_boot_utils.py b/test/py/u_boot_utils.py
>> index 939d82eec12a..e816c7fbb6a3 100644
>> --- a/test/py/u_boot_utils.py
>> +++ b/test/py/u_boot_utils.py
>> @@ -8,6 +8,7 @@
>>  import os
>>  import os.path
>>  import pytest
>> +import signal
>>  import sys
>>  import time
>>  import re
>> @@ -339,3 +340,38 @@ def crc32(u_boot_console, address, count):
>>      assert m, 'CRC32 operation failed.'
>>
>>      return m.group(1)
>> +
>> +def waitpid(pid, timeout=60, kill=False):
>> +    """Wait a process to terminate by its PID
>> +
>> +    This is an alternative to a os.waitpid(pid, 0) call that works on
>> +    processes that aren't children of the python process.
>> +
>> +    Args:
>> +        pid: PID of a running process.
>> +        timeout: Time in seconds to wait.
>> +        kill: Whether to forcibly kill the process after timeout.
>> +
>> +    Returns:
>> +        True, if the process ended on its own.
>> +        False, if the process was killed by this function.
>> +
>> +    Raises:
>> +        TimeoutError, if the process is still running after timeout.
>> +    """
>> +    try:
>> +        for _ in range(timeout):
>> +            os.kill(pid, 0)
>> +            time.sleep(1)
>> +
>> +        if kill:
>> +            os.kill(pid, signal.SIGKILL)
>> +            return False
>> +
>> +    except ProcessLookupError:
>> +        return True
>> +
>> +    raise TimeoutError(
>> +        "Process with PID {} did not terminate after {} seconds."
>> +        .format(pid, timeout)
>> +    )
>> --
>> 2.32.0.rc2
>>

Re: [PATCH 1/2] test/py: Use loop mounts if guestmount fails in filesystem tests

[Tom Rini]

[-- Attachment #1: Type: text/plain, Size: 686 bytes --]

On Fri, Jun 04, 2021 at 10:04:45PM +0300, Alper Nebi Yasak wrote:

> If guestmount isn't available on the system, filesystem test setup falls
> back to using loop mounts to prepare its disk images. If guestmount is
> available but fails to work, the tests are immediately skipped. Instead
> of giving up on a guestmount failure, try using loop mounts as an
> attempt to keep tests running.
> 
> Also stop checking if guestmount is in PATH, as trying to run a missing
> guestmount can now follow the same failure codepath and fall back to
> loop mounts anyway.
> 
> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>

Applied to u-boot/master, thanks!

-- 
Tom

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Re: [PATCH 2/2] test/py: Wait for guestmount worker to exit after running guestunmount

[Tom Rini]

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On Fri, Jun 04, 2021 at 10:04:46PM +0300, Alper Nebi Yasak wrote:

> Some filesystem tests are failing when their image is prepared with
> guestmount, but succeeding if loop mounts are used instead. The reason
> seems to be a race condition the guestmount(1) manual page explains:
> 
>     When guestunmount(1)/fusermount(1) exits, guestmount may still be
>     running and cleaning up the mountpoint.  The disk image will not be
>     fully finalized.
> 
>     This means that scripts like the following have a nasty race condition:
> 
>      guestmount -a disk.img -i /mnt
>      # copy things into /mnt
>      guestunmount /mnt
>      # immediately try to use 'disk.img' ** UNSAFE **
> 
>     The solution is to use the --pid-file option to write the guestmount
>     PID to a file, then after guestunmount spin waiting for this PID to
>     exit.
> 
> The Python standard library has an os.waitpid() function for waiting a
> child to terminate, but it cannot wait on non-child processes. Implement
> a utility function that can do this by polling the process repeatedly
> for a given duration, optionally killing the process if it won't
> terminate on its own. Apply the suggested solution with this utility
> function, which makes the failing tests succeed again.
> 
> Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
> Reviewed-by: Simon Glass <sjg@chromium.org>

Applied to u-boot/master, thanks!

-- 
Tom

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