From: Ingo Molnar <mingo@kernel.org>
To: Yi Sun <yi.y.sun@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
jgross@suse.com, chao.p.peng@intel.com, chao.gao@intel.com,
isaku.yamahata@intel.com, michael.h.kelley@microsoft.com,
tianyu.lan@microsoft.com, "K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>
Subject: Re: [PATCH v4 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V
Date: Wed, 10 Oct 2018 07:50:26 +0200 [thread overview]
Message-ID: <20181010055026.GA17688@gmail.com> (raw)
In-Reply-To: <20181010022536.GH11769@yi.y.sun>
* Yi Sun <yi.y.sun@linux.intel.com> wrote:
> On 18-10-09 12:54:27, Ingo Molnar wrote:
> >
> > * Yi Sun <yi.y.sun@linux.intel.com> wrote:
> >
> > > Follow PV spinlock mechanism to implement the callback functions
> > > to allow the CPU idling and kicking operations on Hyper-V.
> >
> > > +#if defined(CONFIG_SMP)
> > > + smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
> > > +#endif
> >
> > What's wrong with using the common pattern of:
> >
> > #ifdef CONFIG_SMP
> >
> > ?
>
> There is no difference between "#ifdef" and "#if defined". I just copied
> it from "hv_smp_prepare_boot_cpu()". Do you need me submit a fix patch
> after this set is merged?
It's equivalent code, my point was that '#ifdef CONFIG_XYZ' is the shorter, more canonical
pattern we use in the kernel most of the time, it's shorter, easier to read. We only use
defined() for longer preprocessor directive conditions, and it's a pattern for "there's
something more complex here than a simple CONFIG_XYZ dependency".
Anyway, Thomas fixed it up in the latest iteration.
Thanks,
Ingo
next prev parent reply other threads:[~2018-10-10 5:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-08 8:29 [PATCH v4 0/2] Enable PV qspinlock for Hyper-V Yi Sun
2018-10-08 8:29 ` [PATCH v4 1/2] X86/Hyper-V: Add Guest IDLE MSR support Yi Sun
2018-10-08 8:29 ` [PATCH v4 2/2] locking/pvqspinlock, hv: Enable PV qspinlock for Hyper-V Yi Sun
2018-10-08 9:15 ` Juergen Gross
2018-10-09 9:30 ` [tip:x86/hyperv] x86/hyperv: " tip-bot for Yi Sun
2018-10-09 10:54 ` [PATCH v4 2/2] locking/pvqspinlock, hv: " Ingo Molnar
2018-10-10 2:25 ` Yi Sun
2018-10-10 5:50 ` Ingo Molnar [this message]
2018-10-10 8:02 ` Yi Sun
2018-10-09 12:28 ` [tip:x86/paravirt] x86/hyperv: " tip-bot for Yi Sun
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