From: Ashok Raj <ashok.raj@intel.com>
To: Zwane Mwaikambo <zwane@arm.linux.org.uk>, y@unix-os.sc.intel.com
Cc: Ashok Raj <ashok.raj@intel.com>, Andi Kleen <ak@muc.de>,
Andrew Morton <akpm@osdl.org>,
linux-kernel@vger.kernel.org, discuss@x86-64.org,
Rusty Russell <rusty@rustycorp.com.au>,
Srivattsa Vaddagiri <vatsa@in.ibm.com>
Subject: Re: [patch 2/5] x86_64: CPU hotplug support.
Date: Thu, 2 Jun 2005 17:08:20 -0700 [thread overview]
Message-ID: <20050602170820.B17378@unix-os.sc.intel.com> (raw)
In-Reply-To: <Pine.LNX.4.61.0506021742390.3157@montezuma.fsmlabs.com>; from zwane@arm.linux.org.uk on Thu, Jun 02, 2005 at 05:45:14PM -0600
On Thu, Jun 02, 2005 at 05:45:14PM -0600, Zwane Mwaikambo wrote:
> On Thu, 2 Jun 2005, Ashok Raj wrote:
>
> > > > + lock_ipi_call_lock();
> > > > cpu_set(smp_processor_id(), cpu_online_map);
> > > > mb();
> > > > + unlock_ipi_call_lock();
> > >
> > > What's that? Is this another smp_call_function race workaround? I thought
> > > there was an additional patch to avoid the broadcast.
> >
> > The other patch avoids sending to offline cpu's, but we read cpu_online_map
> > and clear self bit in smp_call_function. If a cpu comes online, dont we
> > want this cpu to take part in smp_call_function?
>
> The lock being held in smp_call_function whilst we access cpu_online_map
> should prevent another processor coming online within that operation
> shouldn't it? So There shouldn't be any processors coming online except
> for right after or before an smp_call_function.
precicely why we hold the same lock when we set the bit in cpu_online_map
during cpu_up as well.
next prev parent reply other threads:[~2005-06-03 0:09 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-02 12:57 [patch 0/5] x86_64 CPU hotplug patch series Ashok Raj
2005-06-02 12:57 ` [patch 1/5] x86_64: Change init sections for CPU hotplug support Ashok Raj
2005-06-02 20:14 ` Zwane Mwaikambo
2005-06-02 23:19 ` Ashok Raj
2005-06-02 12:57 ` [patch 2/5] x86_64: " Ashok Raj
2005-06-02 20:19 ` Zwane Mwaikambo
2005-06-02 23:33 ` Ashok Raj
2005-06-02 23:45 ` Zwane Mwaikambo
2005-06-03 0:08 ` Ashok Raj [this message]
2005-06-03 2:01 ` Shaohua Li
2005-06-03 14:25 ` Ashok Raj
2005-06-02 12:57 ` [patch 3/5] x86_64: CPU hotplug sibling map cleanup Ashok Raj
2005-06-02 12:57 ` [patch 4/5] x86_64: Dont use broadcast shortcut to make it cpu hotplug safe Ashok Raj
2005-06-02 12:58 ` [patch 5/5] x86_64: Provide ability to choose using shortcuts for IPI in flat mode Ashok Raj
2005-06-02 20:10 ` Zwane Mwaikambo
2005-06-02 23:15 ` Ashok Raj
2005-06-02 20:25 ` [patch 0/5] x86_64 CPU hotplug patch series Zwane Mwaikambo
2005-06-03 16:35 ` Andi Kleen
2005-06-03 17:15 ` Ashok Raj
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