Messages in this thread | | | From | John Ogness <> | Subject | Re: [PATCH rcu 11/12] torture: Flush printk() buffers before powering off | Date | Tue, 21 Jun 2022 22:58:27 +0206 |
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On 2022-06-21, "Paul E. McKenney" <paulmck@kernel.org> wrote: > The patch below will cause rcutorture to implicitly test this > functionality, unless told otherwise, for example, by using the > --bootargs "torture.printk_shutdown_bug_workaround" kvm.sh > argument. > > Thoughts?
I feel like this is dirtying the torture.* bootarg namespace a bit. Also, I am not sure how useful it is as a dynamic option. I assume that users would generally avoid using it, so its very existence might just be more noise in the documentation and code. It is an unusual feature:
"In case some bug shows up, here is a flag to avoid it."
I personally would just drop the patch and rely on a correctly functional kernel. But I am also not an rcutorture user. If _you_ think that such a flag is useful, feel free to include the patch.
> commit 204bf1e2a5a2fb68c15b4b64793ad0896db6f705 > Author: Paul E. McKenney <paulmck@kernel.org> > Date: Tue Jun 21 11:02:25 2022 -0700 > > torture: Optionally flush printk() buffers before powering off > > The rcutorture test suite produces quite a bit of console output at > the end of a test. This means that the new-in-2022 printk() kthreads > are likely to be in the process of flushing output at the time of the > torture_shutdown() function's call to kernel_power_off(). Normally, > rcutorture relies on printk() to flush any pending output upon shutdown, > the better to detect bugs in this area, for example, the one introduced > by 8e274732115f ("printk: extend console_lock for per-console locking"). > However, once such a bug is detected and reported, it is necessary to > test the rest of the system, without noise from the already-reported bug. > > This commit therefore adds a torture.printk_shutdown_bug_workaround > kernel parameter, which causes torture_shutdown() to invoke pr_flush(), > and print an informative message on the console, immediately before > invoking kernel_power_off(). When this kernel parameter is not specified, > it is up to printk() to flush its own buffers. > > Suggested-by: John Ogness <john.ogness@linutronix.de> > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: John Ogness <john.ogness@linutronix.de>
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