From: marc_gonzalez@sigmadesigns•com (Marc Gonzalez)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 1/2] ARM: tango: add HOTPLUG_CPU support
Date: Tue, 28 Jun 2016 17:04:17 +0200 [thread overview]
Message-ID: <577291F1.8060105@sigmadesigns.com> (raw)
In-Reply-To: <57726DE0.8090308@arm.com>
On 28/06/2016 14:30, Robin Murphy wrote:
> On 28/06/16 12:59, Marc Gonzalez wrote:
>
>> +#ifdef CONFIG_HOTPLUG_CPU
>> +/*
>> + * cpu_kill() and cpu_die() run concurrently on different cores.
>> + * Firmware will only "kill" a core once it has properly "died".
>> + * Keep trying to kill a core until the operation succeeds, but
>> + * sleep between tries to give the core time to die.
>> + */
>> +static int tango_cpu_kill(unsigned int cpu)
>> +{
>> + do {
>> + msleep(10);
>> + } while (tango_aux_core_kill(cpu) != 0);
>
> Does the firmware guarantee that this will succeed (or at least report
> success) in finite time, regardless of how messed up the system might
> be? I'd imagine this should probably have either a timeout or a comment
> clarifying why it doesn't need a timeout.
Good point.
The FW allows only one thread at a time. If a thread is wedged inside
the FW, no other thread can use the FW. In that situation, cpu0 would
remain stuck inside tango_cpu_kill().
Note, that if tango_cpu_kill() starts failing, then secondary cores
will remain "zombies". So the system is mostly hosed anyway...
Only cpu0 will be available.
Regards.
next prev parent reply other threads:[~2016-06-28 15:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-28 11:55 [PATCH v3 0/2] [for arm-soc] mach-tango updates for v4.8 Marc Gonzalez
2016-06-28 11:59 ` [PATCH v3 1/2] ARM: tango: add HOTPLUG_CPU support Marc Gonzalez
2016-06-28 12:30 ` Robin Murphy
2016-06-28 15:04 ` Marc Gonzalez [this message]
2016-06-28 15:16 ` Robin Murphy
2016-06-29 12:28 ` Marc Gonzalez
2016-06-29 12:21 ` [PATCH v4 " Marc Gonzalez
2016-06-28 12:01 ` [PATCH v3 2/2] Update ARM/TANGO section Marc Gonzalez
2016-07-05 12:32 ` [PATCH v3 0/2] [for arm-soc] mach-tango updates for v4.8 Mason
2016-07-06 3:57 ` Olof Johansson
2016-07-06 20:04 ` Arnd Bergmann
2016-07-07 4:45 ` Olof Johansson
2016-07-07 8:50 ` Mason
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