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Re: [PATCH v8 13/21] main: keep rcu_atfork callback enabled for qtest
From: |
Thomas Huth |
Subject: |
Re: [PATCH v8 13/21] main: keep rcu_atfork callback enabled for qtest |
Date: |
Thu, 18 Jun 2020 09:34:51 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 |
On 29/01/2020 06.34, Bulekov, Alexander wrote:
> The qtest-based fuzzer makes use of forking to reset-state between
> tests. Keep the callback enabled, so the call_rcu thread gets created
> within the child process.
>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
> vl.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/vl.c b/vl.c
> index bb77935f04..cf8e2d3ebb 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -3794,7 +3794,14 @@ void qemu_init(int argc, char **argv, char **envp)
> set_memory_options(&ram_slots, &maxram_size, machine_class);
>
> os_daemonize();
> - rcu_disable_atfork();
> +
> + /*
> + * If QTest is enabled, keep the rcu_atfork enabled, since system
> processes
> + * may be forked testing purposes (e.g. fork-server based fuzzing)
> + */
> + if (!qtest_enabled()) {
> + rcu_disable_atfork();
> + }
>
> if (pid_file && !qemu_write_pidfile(pid_file, &err)) {
> error_reportf_err(err, "cannot create PID file: ");
Hi Alexander,
I think this patch might maybe not work as expected: The qtest_enabled()
has been added before configure_accelerators() is called in main(). So
qtest_enabled() should always return "false" and thus
rcu_disabled_fork() is still called in any case... could you please
double-check whether it works for you and I just made a mistake, or
whether this is a bug indeed?
Thanks,
Thomas
- Re: [PATCH v8 13/21] main: keep rcu_atfork callback enabled for qtest,
Thomas Huth <=