From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH] xen: arm: wait 1000ms for a CPU to come up, instead of forever Date: Wed, 14 Jan 2015 14:27:22 +0000 Message-ID: <54B67CCA.9060205@linaro.org> References: <1421244060-1745-1-git-send-email-ian.campbell@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1421244060-1745-1-git-send-email-ian.campbell@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , xen-devel@lists.xen.org Cc: tim@xen.org, stefano.stabellini@eu.citrix.com List-Id: xen-devel@lists.xenproject.org Hi Ian, On 14/01/15 14:01, Ian Campbell wrote: > Otherwise continue without it, which is preferable to the current > infinite hang. Nice! > Slightly tweak the grammar of a comment in the same function. > > Signed-off-by: Ian Campbell > --- > xen/arch/arm/smpboot.c | 26 ++++++++++++++++++++++++-- > 1 file changed, 24 insertions(+), 2 deletions(-) > > diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c > index 14054ae..12538d4 100644 > --- a/xen/arch/arm/smpboot.c > +++ b/xen/arch/arm/smpboot.c > @@ -357,6 +357,7 @@ int __init cpu_up_send_sgi(int cpu) > int __cpu_up(unsigned int cpu) > { > int rc; > + s_time_t deadline; > > printk("Bringing up CPU%d\n", cpu); > > @@ -369,7 +370,7 @@ int __cpu_up(unsigned int cpu) > /* Tell the remote CPU which stack to boot on. */ > init_data.stack = idle_vcpu[cpu]->arch.stack; > > - /* Tell the remote CPU what is it's logical CPU ID */ > + /* Tell the remote CPU what its logical CPU ID is. */ > init_data.cpuid = cpu; > > /* Open the gate for this CPU */ > @@ -386,12 +387,33 @@ int __cpu_up(unsigned int cpu) > return rc; > } > > - while ( !cpu_online(cpu) ) > + deadline = NOW() + MILLISECS(1000); Most of cpu_up callbacks are waiting for the CPU to come back. I guess this deadline is for the time to initialize the CPU for Xen? If so, maybe you can add a comment for it. Also, any reason for 1s? > + > + while ( !cpu_online(cpu) && NOW() < deadline ) > { > cpu_relax(); > process_pending_softirqs(); > } > > + /* > + * Nuke start of day info before checking one last time if the CPU > + * actually came online. > + * > + * Doesn't completely avoid the posibility of it trying to possibility > + * progress with another CPUs stack etc, but better than nothing, > + * hopefully. > + */ > + init_data.stack = NULL; > + init_data.cpuid = ~0; > + smp_up_cpu = MPIDR_INVALID; > + clean_dcache(smp_up_cpu); I don't understand why you need to do this. Is it for pure clean up? If so, please explain it in the commit message. Regards, -- Julien Grall