From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com
Cc: linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Question about tboot_wait_for_aps()
Date: Tue, 24 Jul 2012 08:58:53 -0700 [thread overview]
Message-ID: <20120724155853.GA32362@linux.vnet.ibm.com> (raw)
Hello!
While taking another pass through the CPU_DYING notifiers, I came upon
the following:
static int tboot_wait_for_aps(int num_aps)
{
unsigned long timeout;
timeout = AP_WAIT_TIMEOUT*HZ;
while (atomic_read((atomic_t *)&tboot->num_in_wfs) != num_aps &&
timeout) {
mdelay(1);
timeout--;
}
if (timeout)
pr_warning("tboot wait for APs timeout\n");
return !(atomic_read((atomic_t *)&tboot->num_in_wfs) == num_aps);
}
Questions:
1. Why AP_WAIT_TIMEOUT*HZ? Given the mdelay(), shouldn't this
instead be AP_WAIT_TIMEOUT*1000? The definition of AP_WAIT_TIMEOUT
indicates that it is in seconds.
2. Who changes ->num_in_wfs? Any other CPUs are in stop_machine(),
plus I don't see any assignments to this field. Does the boot
firmware run again to make this change, sort of like SMIs?
I guess that the good news is that I don't seen anything that cares about
stop_machine(). ;-)
Thanx, Paul
reply other threads:[~2012-07-24 16:40 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120724155853.GA32362@linux.vnet.ibm.com \
--to=paulmck@linux.vnet.ibm.com \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=tglx@linutronix.de \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.