From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@au1.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
"H. Peter Anvin" <hpa@zytor.com>,
James Hogan <james.hogan@imgtec.com>,
"James E.J. Bottomley" <jejb@parisc-linux.org>,
Helge Deller <deller@gmx.de>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
"David S. Miller" <davem@davemloft.net>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC GIT PULL] softirq: Consolidation and stack overrun fix
Date: Wed, 25 Sep 2013 06:55:47 +1000 [thread overview]
Message-ID: <1380056147.5443.61.camel@pasglop> (raw)
In-Reply-To: <20130924135622.GA21410@localhost.localdomain>
On Tue, 2013-09-24 at 15:56 +0200, Frederic Weisbecker wrote:
> On Tue, Sep 24, 2013 at 02:42:57PM +1000, Benjamin Herrenschmidt wrote:
> > On Tue, 2013-09-24 at 04:44 +0200, Frederic Weisbecker wrote:
> > > So the safest way to fix this is to unconditionally call do_softirq()
> > > from irq_exit().
> > > A performance penalty may come along but safety primes.
> > >
> > > We should probably do that and work on longer term solutions (Kconfig
> > > based arch switch, etc...)
> > > for the next merge window?
> >
> > As you prefer, though I'm keen on getting the "fast" version in RHEL7 if
> > RH will take it :-)
>
> So what is the fast version? Converting __do_softirq() to do_softirq()
> unconditionally.
>
> RH will accept any fix that goes upstream.
No, me fixing powerpc do_IRQ to do irq_exit run on the irq stack, and
your fix for everybody else with an ifdef such that x86_64 and powerpc
get to skip the additional stack switch.
> >
> > From the generic code POV, it's a one-liner #ifdef to select between
> > do_softirq and __do_softirq() right ? Then it's up to the arch to
> > #define I_CAN_DO_FAST !
>
> I'd rather say #define I_CAN_DO_SAFE :)
>
> But I guess the kind of symbol we want is some ARCH_HAS_IRQ_STACK_LOW_HANDLER
ARCH_IRQ_EXIT_ON_IRQ_STACK
Cheers,
Ben.
> >
> > > I'll respin the series plus the regression fix, unless somebody has a
> > > better solution.
> >
> > Cheers,
> > Ben.
> >
> >
next prev parent reply other threads:[~2013-09-24 20:57 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-19 19:51 [RFC GIT PULL] softirq: Consolidation and stack overrun fix Frederic Weisbecker
2013-09-19 19:51 ` [PATCH 1/3] irq: Consolidate do_softirq() arch overriden implementations Frederic Weisbecker
2013-09-19 19:51 ` [PATCH 2/3] irq: Execute softirq on its own stack on irq exit Frederic Weisbecker
2013-09-19 19:51 ` [PATCH 3/3] irq: Comment on the use of inline stack for ksoftirqd Frederic Weisbecker
2013-09-20 0:02 ` [RFC GIT PULL] softirq: Consolidation and stack overrun fix Linus Torvalds
2013-09-20 1:53 ` Benjamin Herrenschmidt
2013-09-20 11:03 ` Thomas Gleixner
2013-09-20 11:11 ` Peter Zijlstra
2013-09-21 0:55 ` Benjamin Herrenschmidt
2013-09-20 16:26 ` Frederic Weisbecker
2013-09-20 17:30 ` Thomas Gleixner
2013-09-20 18:37 ` Frederic Weisbecker
2013-09-20 22:14 ` Linus Torvalds
2013-09-21 7:47 ` Ingo Molnar
2013-09-21 18:58 ` Frederic Weisbecker
2013-09-21 21:45 ` Benjamin Herrenschmidt
2013-09-21 23:27 ` Frederic Weisbecker
2013-09-22 2:01 ` H. Peter Anvin
2013-09-22 4:39 ` Benjamin Herrenschmidt
2013-09-22 4:41 ` Benjamin Herrenschmidt
2013-09-22 16:24 ` Peter Zijlstra
2013-09-22 17:47 ` H. Peter Anvin
2013-09-22 22:00 ` Benjamin Herrenschmidt
2013-09-22 21:56 ` Benjamin Herrenschmidt
2013-09-22 22:22 ` Linus Torvalds
2013-09-22 22:38 ` Benjamin Herrenschmidt
2013-09-23 4:35 ` [PATCH] powerpc/irq: Run softirqs off the top of the irq stack Benjamin Herrenschmidt
2013-09-23 4:35 ` Benjamin Herrenschmidt
2013-09-23 7:56 ` Stephen Rothwell
2013-09-23 7:56 ` Stephen Rothwell
2013-09-23 10:13 ` Benjamin Herrenschmidt
2013-09-23 10:13 ` Benjamin Herrenschmidt
2013-09-23 16:47 ` Linus Torvalds
2013-09-23 16:47 ` Linus Torvalds
2013-09-23 20:51 ` Benjamin Herrenschmidt
2013-09-23 20:51 ` Benjamin Herrenschmidt
2013-09-24 5:42 ` [PATCH v2] " Benjamin Herrenschmidt
2013-09-24 5:42 ` Benjamin Herrenschmidt
2013-09-23 17:59 ` [RFC GIT PULL] softirq: Consolidation and stack overrun fix Chris Metcalf
2013-09-23 20:57 ` Benjamin Herrenschmidt
2013-09-24 19:27 ` Chris Metcalf
2013-09-24 20:58 ` Benjamin Herrenschmidt
2013-09-24 0:10 ` Benjamin Herrenschmidt
2013-09-24 1:19 ` Linus Torvalds
2013-09-24 1:52 ` Benjamin Herrenschmidt
2013-09-24 8:04 ` Peter Zijlstra
2013-09-24 8:16 ` Benjamin Herrenschmidt
2013-09-24 8:21 ` Peter Zijlstra
2013-09-24 9:31 ` Benjamin Herrenschmidt
2013-09-23 4:40 ` Benjamin Herrenschmidt
2013-09-23 5:01 ` David Miller
2013-09-24 2:44 ` Frederic Weisbecker
2013-09-24 4:42 ` Benjamin Herrenschmidt
2013-09-24 13:56 ` Frederic Weisbecker
2013-09-24 20:55 ` Benjamin Herrenschmidt [this message]
2013-09-25 8:46 ` Frederic Weisbecker
2013-09-21 0:52 ` Benjamin Herrenschmidt
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