linux-kernel - Re: [PATCH PREEMPT_RT] kcov: fix locking splat from kcov_remote

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Message-ID: <20210810151428.3e02d386@oasis.local.home>
Date:   Tue, 10 Aug 2021 15:14:28 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Clark Williams <williams@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH PREEMPT_RT] kcov:  fix locking splat from
 kcov_remote_start()

On Tue, 10 Aug 2021 11:50:32 +0200
Sebastian Andrzej Siewior <bigeasy@...utronix.de> wrote:

> - With lock kcov_remote_lock acquired there is a possible
>   hash_for_each_safe() and list_for_each() iteration. I don't know what
>   the limits are here but with a raw_spinlock_t it will contribute to
>   the maximal latency. 

Note, anyone having a kernel with KCOV compiled in, probably doesn't
care about latency ;-) It's like worrying about latency when lockdep is
complied in.

-- Steve