From: Frederic Weisbecker <frederic@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
x86 <x86@kernel.org>
Subject: Re: [tip: locking/core] lockdep: Annotate irq_work
Date: Sun, 22 Mar 2020 03:33:30 +0100 [thread overview]
Message-ID: <20200322023329.GC9634@lenoir> (raw)
In-Reply-To: <20200321181249.vy7xxkgrd65piapw@linutronix.de>
On Sat, Mar 21, 2020 at 07:12:49PM +0100, Sebastian Andrzej Siewior wrote:
> On 2020-03-21 17:40:58 [+0100], Frederic Weisbecker wrote:
> > > diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h
> > > index 9c17f9c..f23f540 100644
> > > --- a/include/linux/irqflags.h
> > > +++ b/include/linux/irqflags.h
> > > @@ -69,6 +69,17 @@ do { \
> > > current->irq_config = 0; \
> > > } while (0)
> > >
> > > +# define lockdep_irq_work_enter(__work) \
> > > + do { \
> > > + if (!(atomic_read(&__work->flags) & IRQ_WORK_HARD_IRQ))\
> > > + current->irq_config = 1; \
> >
> > So, irq_config == 1 means we are in a softirq? Are there other values for
> > irq_config? In which case there should be enums or something?
> > I can't find the patch that describes this.
>
> 0 means as-is, 1 means threaded / sleeping locks are okay.
So that's the kind of comment we need :-)
Also how about current->irq_locking instead?
And something like:
enum {
IRQ_LOCKING_NO_SLEEP,
IRQ_LOCKING_CAN_SLEEP
}
>
> > > --- a/kernel/time/tick-sched.c
> > > +++ b/kernel/time/tick-sched.c
> > > @@ -245,6 +245,7 @@ static void nohz_full_kick_func(struct irq_work *work)
> > >
> > > static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = {
> > > .func = nohz_full_kick_func,
> > > + .flags = ATOMIC_INIT(IRQ_WORK_HARD_IRQ),
> > > };
> >
> > I get why these need to be in hardirq but some basic explanations for
> > ordinary mortals as to why those two specifically and not all the others
> > (and there are many) would have been nice.
>
> Is the documentation patch in this series any good?
That describes the general rules but it doesn't tell anything about the
details of this patch. Especially why RCU and nohz_full irq works in particular
are special here and why it's fine for others to execute in softirq.
Thanks.
> > Thanks.
>
> Sebastian
next prev parent reply other threads:[~2020-03-22 2:33 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-21 11:25 [patch V3 00/20] Lock ordering documentation and annotation for lockdep Thomas Gleixner
2020-03-21 11:25 ` [patch V3 01/20] PCI/switchtec: Fix init_completion race condition with poll_wait() Thomas Gleixner
2020-03-21 11:25 ` [patch V3 02/20] pci/switchtec: Replace completion wait queue usage for poll Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 11:25 ` [patch V3 03/20] usb: gadget: Use completion interface instead of open coding it Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-03-25 8:37 ` [patch V3 03/20] " Felipe Balbi
2020-03-27 12:14 ` Sebastian Siewior
2020-03-21 11:25 ` [patch V3 04/20] orinoco_usb: Use the regular completion interfaces Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-03-21 11:25 ` [patch V3 05/20] acpi: Remove header dependency Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-03-21 11:25 ` [patch V3 06/20] nds32: Remove mm.h from asm/uaccess.h Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 11:25 ` [patch V3 07/20] csky: " Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 11:25 ` [patch V3 08/20] hexagon: " Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-23 21:46 ` [patch V3 08/20] " Brian Cain
2020-03-21 11:25 ` [patch V3 09/20] ia64: " Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 11:25 ` [patch V3 10/20] microblaze: " Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 11:25 ` [patch V3 11/20] rcuwait: Add @state argument to rcuwait_wait_event() Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra (Intel)
2020-03-21 11:25 ` [patch V3 12/20] powerpc/ps3: Convert half completion to rcuwait Thomas Gleixner
2020-03-21 13:22 ` Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra (Intel)
2020-03-27 19:14 ` [patch V3 12/20] " Geoff Levand
2020-03-21 11:25 ` [patch V3 13/20] Documentation: Add lock ordering and nesting documentation Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-03-23 2:55 ` [patch V3 13/20] " Paul E. McKenney
2020-03-24 23:13 ` Thomas Gleixner
2020-03-25 0:28 ` Paul E. McKenney
2020-03-25 12:27 ` Documentation/locking/locktypes: Further clarifications and wordsmithing Thomas Gleixner
2020-03-25 16:02 ` Sebastian Siewior
2020-03-25 16:39 ` Paul E. McKenney
2020-03-25 16:54 ` Sebastian Siewior
2020-03-25 16:58 ` [PATCH v2] Documentation/locking/locktypes: minor copy editor fixes Randy Dunlap
2020-03-26 2:40 ` Paul E. McKenney
2020-03-28 11:52 ` [tip: locking/core] Documentation/locking/locktypes: Minor " tip-bot2 for Randy Dunlap
2020-03-28 11:52 ` [tip: locking/core] Documentation/locking/locktypes: Further clarifications and wordsmithing tip-bot2 for Thomas Gleixner
2020-03-21 11:25 ` [patch V3 14/20] timekeeping: Split jiffies seqlock Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-03-21 11:25 ` [patch V3 15/20] sched/swait: Prepare usage in completions Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-03-21 11:26 ` [patch V3 16/20] completion: Use simple wait queues Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Thomas Gleixner
2020-03-23 15:20 ` [PATCH] completion: Use lockdep_assert_RT_in_threaded_ctx() in complete_all() Sebastian Siewior
2020-03-23 17:50 ` [tip: locking/core] " tip-bot2 for Sebastian Siewior
2020-03-21 11:26 ` [patch V3 17/20] lockdep: Introduce wait-type checks Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Peter Zijlstra
2020-03-21 11:26 ` [patch V3 18/20] lockdep: Add hrtimer context tracing bits Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 16:46 ` Frederic Weisbecker
2020-03-21 11:26 ` [patch V3 19/20] lockdep: Annotate irq_work Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 16:40 ` Frederic Weisbecker
2020-03-21 18:12 ` Sebastian Andrzej Siewior
2020-03-22 2:33 ` Frederic Weisbecker [this message]
2020-03-22 2:39 ` Frederic Weisbecker
2020-03-22 12:27 ` Sebastian Andrzej Siewior
2020-03-21 11:26 ` [patch V3 20/20] lockdep: Add posixtimer context tracing bits Thomas Gleixner
2020-03-21 15:53 ` [tip: locking/core] " tip-bot2 for Sebastian Andrzej Siewior
2020-03-21 17:19 ` [patch V3 00/20] Lock ordering documentation and annotation for lockdep Davidlohr Bueso
2020-03-21 17:45 ` Thomas Gleixner
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