From: Peter Zijlstra <peterz@infradead.org>
To: Marco Elver <elver@google.com>
Cc: LKMM Maintainers -- Akira Yokosawa <akiyks@gmail.com>,
Alan Stern <stern@rowland.harvard.edu>,
Alexander Potapenko <glider@google.com>,
Andrea Parri <parri.andrea@gmail.com>,
Andrey Konovalov <andreyknvl@google.com>,
Andy Lutomirski <luto@kernel.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Arnd Bergmann <arnd@arndb.de>, Boqun Feng <boqun.feng@gmail.com>,
Borislav Petkov <bp@alien8.de>, Daniel Axtens <dja@axtens.net>,
Daniel Lustig <dlustig@nvidia.com>,
dave.hansen@linux.intel.com, David Howells <dhowells@redhat.com>,
Dmitry Vyukov <dvyukov@google.com>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
Jade Alglave <j.alglave@ucl.ac.uk>,
Joel Fernandes <joel@joelfernandes.org>,
Jonathan Corbet <corbet@lwn.net>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Luc Maranget <luc.maranget@inria.fr>,
Mark Rutland <mark.rutland@arm.com>,
Nicholas Piggin <npiggin@gmail.com>,
"Paul E. McKenney" <paulmck@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
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linux-arch <linux-arch@vger.kernel.org>,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
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Subject: Re: [PATCH 1/8] kcsan: Add Kernel Concurrency Sanitizer infrastructure
Date: Thu, 17 Oct 2019 09:47:30 +0200 [thread overview]
Message-ID: <20191017074730.GW2328@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CANpmjNP4b9Eo3ZKE6maBs4ANS7K7sLiVB2CbebQnCH09TB+hZQ@mail.gmail.com>
On Wed, Oct 16, 2019 at 09:34:05PM +0200, Marco Elver wrote:
> On Wed, 16 Oct 2019 at 20:44, Peter Zijlstra <peterz@infradead.org> wrote:
> > > + /*
> > > + * Disable interrupts & preemptions, to ignore races due to accesses in
> > > + * threads running on the same CPU.
> > > + */
> > > + local_irq_save(irq_flags);
> > > + preempt_disable();
> >
> > Is there a point to that preempt_disable() here?
>
> We want to avoid being preempted while the watchpoint is set up;
> otherwise, we would report data-races for CPU-local data, which is
> incorrect.
Disabling IRQs already very much disables preemption. There is
absolutely no point in doing preempt_disable() when the whole section
already runs with IRQs disabled.
next prev parent reply other threads:[~2019-10-17 7:47 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-16 8:39 [PATCH 0/8] Add Kernel Concurrency Sanitizer (KCSAN) Marco Elver
2019-10-16 8:39 ` [PATCH 1/8] kcsan: Add Kernel Concurrency Sanitizer infrastructure Marco Elver
2019-10-16 9:42 ` Boqun Feng
2019-10-16 10:06 ` Marco Elver
2019-10-17 0:25 ` Boqun Feng
2019-10-16 11:49 ` Andrey Konovalov
2019-10-16 13:52 ` Marco Elver
2019-10-16 15:16 ` Mark Rutland
2019-10-16 15:53 ` Marco Elver
2019-10-16 18:43 ` Peter Zijlstra
2019-10-16 19:34 ` Marco Elver
2019-10-17 7:47 ` Peter Zijlstra [this message]
2019-10-17 7:49 ` Marco Elver
2019-10-16 8:39 ` [PATCH 2/8] objtool, kcsan: Add KCSAN runtime functions to whitelist Marco Elver
2019-10-16 8:39 ` [PATCH 3/8] build, kcsan: Add KCSAN build exceptions Marco Elver
2019-10-16 8:39 ` [PATCH 4/8] seqlock, kcsan: Add annotations for KCSAN Marco Elver
2019-10-16 8:39 ` [PATCH 5/8] seqlock: Require WRITE_ONCE surrounding raw_seqcount_barrier Marco Elver
2019-10-16 8:39 ` [PATCH 6/8] asm-generic, kcsan: Add KCSAN instrumentation for bitops Marco Elver
2019-10-16 8:39 ` [PATCH 7/8] locking/atomics, kcsan: Add KCSAN instrumentation Marco Elver
2019-10-16 11:18 ` Mark Rutland
2019-10-16 11:47 ` Marco Elver
2019-10-16 8:39 ` [PATCH 8/8] x86, kcsan: Enable KCSAN for x86 Marco Elver
2019-10-16 16:14 ` Dave Hansen
2019-10-16 17:04 ` Marco Elver
2019-10-17 14:15 ` [PATCH 0/8] Add Kernel Concurrency Sanitizer (KCSAN) Marco Elver
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