Commit e02b52ec authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

selftests: net: py: support ksft ready without wait 



There's a common synchronization problem when a script (Python test)
uses a C program to set up some state (usually start a receiving
process for traffic). The script needs to know when the process
has fully initialized. The inverse of the problem exists for shutting
the process down - we need a reliable way to tell the process to exit.

We added helpers to do this safely in
commit 71477137 ("selftests: drv-net: add a way to wait for a local process")
unfortunately the two operations (wait for init, and shutdown) are
controlled by a single parameter (ksft_wait). Add support for using
ksft_ready without using the second fd for exit.

This is useful for programs which wait for a specific number of packets
to rx so exit_wait is a good match, but we still need to wait for init.

Reviewed-by: default avatarPetr Machata <petrm@nvidia.com>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Reviewed-by: default avatarbreno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20251120021024.2944527-7-kuba@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 89268f7d

tools/testing/selftests/net/lib/py/utils.py

+12 −8
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ class cmd: 
    Use bkg() instead to run a command in the background.

    """

    def __init__(self, comm, shell=None, fail=True, ns=None, background=False,

                 host=None, timeout=5, ksft_wait=None):

                 host=None, timeout=5, ksft_ready=None, ksft_wait=None):

        if ns:

            comm = f'ip netns exec {ns} ' + comm
@@ -52,21 +52,25 @@ class cmd: 
            # ksft_wait lets us wait for the background process to fully start,

            # we pass an FD to the child process, and wait for it to write back.

            # Similarly term_fd tells child it's time to exit.

            pass_fds = ()

            pass_fds = []

            env = os.environ.copy()

            if ksft_wait is not None:

                rfd, ready_fd = os.pipe()

                wait_fd, self.ksft_term_fd = os.pipe()

                pass_fds = (ready_fd, wait_fd, )

                env["KSFT_READY_FD"] = str(ready_fd)

                pass_fds.append(wait_fd)

                env["KSFT_WAIT_FD"]  = str(wait_fd)

                ksft_ready = True  # ksft_wait implies ready

            if ksft_ready is not None:

                rfd, ready_fd = os.pipe()

                pass_fds.append(ready_fd)

                env["KSFT_READY_FD"] = str(ready_fd)



            self.proc = subprocess.Popen(comm, shell=shell, stdout=subprocess.PIPE,

                                         stderr=subprocess.PIPE, pass_fds=pass_fds,

                                         env=env)

            if ksft_wait is not None:

                os.close(ready_fd)

                os.close(wait_fd)

            if ksft_ready is not None:

                os.close(ready_fd)

                msg = fd_read_timeout(rfd, ksft_wait)

                os.close(rfd)

                if not msg:
@@ -116,10 +120,10 @@ class bkg(cmd): 
        with bkg("my_binary", ksft_wait=5):

    """

    def __init__(self, comm, shell=None, fail=None, ns=None, host=None,

                 exit_wait=False, ksft_wait=None):

                 exit_wait=False, ksft_ready=None, ksft_wait=None):

        super().__init__(comm, background=True,

                         shell=shell, fail=fail, ns=ns, host=host,

                         ksft_wait=ksft_wait)

                         ksft_ready=ksft_ready, ksft_wait=ksft_wait)

        self.terminate = not exit_wait and not ksft_wait

        self._exit_wait = exit_wait

        self.check_fail = fail