From: "Paul E. McKenney" <paulmck@linux.ibm.com>
To: Scott Wood <swood@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
Juri Lelli <juri.lelli@redhat.com>,
Clark Williams <williams@redhat.com>,
linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RT 1/4] rcu: Acquire RCU lock when disabling BHs
Date: Thu, 20 Jun 2019 15:16:07 -0700 [thread overview]
Message-ID: <20190620221607.GA26519@linux.ibm.com> (raw)
In-Reply-To: <8bcc818b1b08850e109d1cde529ab98c4ed788df.camel@redhat.com>
On Thu, Jun 20, 2019 at 04:38:47PM -0500, Scott Wood wrote:
> On Thu, 2019-06-20 at 14:20 -0700, Paul E. McKenney wrote:
> > On Thu, Jun 20, 2019 at 04:06:02PM -0500, Scott Wood wrote:
> > > On Thu, 2019-06-20 at 13:53 -0700, Paul E. McKenney wrote:
> > > > And I have to ask...
> > > >
> > > > What did you do to test this change to kernel/softirq.c? My past
> > > > attempts
> > > > to do this sort of thing have always run afoul of open-coded BH
> > > > transitions.
> > >
> > > Mostly rcutorture and loads such as kernel builds, on a debug
> > > kernel. By
> > > "open-coded BH transition" do you mean directly manipulating the preempt
> > > count? That would already be broken on RT.
> >
> > OK, then maybe you guys have already done the needed cleanup work. Cool!
>
> Do you remember what code was doing such things? Grepping for the obvious
> things doesn't turn up anything outside the softirq code, even in the
> earlier non-RT kernels I checked.
It was many years ago, and it is quite possible that I am conflating
irqs with bh or some such. If it now works, it now works.
> > But don't the additions of rcu_read_lock() and rcu_read_unlock() want
> > to be protected by "!IS_ENABLED(CONFIG_PREEMPT_RT_FULL)" or similar?
>
> This is already a separate PREEMPT_RT_FULL-specific implementation.
Ah, sorry for the noise, then!
Thanx, Paul
next prev parent reply other threads:[~2019-06-20 22:16 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-19 1:19 [PATCH RT 0/4] Address rcutorture issues Scott Wood
2019-06-19 1:19 ` [PATCH RT 1/4] rcu: Acquire RCU lock when disabling BHs Scott Wood
2019-06-20 20:53 ` Paul E. McKenney
2019-06-20 21:06 ` Scott Wood
2019-06-20 21:20 ` Paul E. McKenney
2019-06-20 21:38 ` Scott Wood
2019-06-20 22:16 ` Paul E. McKenney [this message]
2019-06-19 1:19 ` [PATCH RT 2/4] sched: migrate_enable: Use sleeping_lock to indicate involuntary sleep Scott Wood
2019-06-19 1:19 ` [RFC PATCH RT 3/4] rcu: unlock special: Treat irq and preempt disabled the same Scott Wood
2019-06-20 21:10 ` Paul E. McKenney
2019-06-20 21:59 ` Scott Wood
2019-06-20 22:25 ` Paul E. McKenney
2019-06-20 23:08 ` Scott Wood
2019-06-22 0:26 ` Paul E. McKenney
2019-06-22 19:13 ` Paul E. McKenney
2019-06-24 17:40 ` Scott Wood
2019-06-19 1:19 ` [RFC PATCH RT 4/4] rcutorture: Avoid problematic critical section nesting Scott Wood
2019-06-20 21:18 ` Paul E. McKenney
2019-06-20 21:43 ` Scott Wood
2019-06-21 16:38 ` Sebastian Andrzej Siewior
2019-06-21 23:59 ` Paul E. McKenney
2019-06-26 15:08 ` Steven Rostedt
2019-06-26 16:49 ` Scott Wood
2019-06-27 18:00 ` Paul E. McKenney
2019-06-27 20:16 ` Scott Wood
2019-06-27 20:50 ` Paul E. McKenney
2019-06-27 22:46 ` Scott Wood
2019-06-28 0:52 ` Paul E. McKenney
2019-06-28 19:37 ` Scott Wood
2019-06-28 20:24 ` Paul E. McKenney
2019-06-20 19:12 ` [PATCH RT 0/4] Address rcutorture issues Paul E. McKenney
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