From: Dexuan Cui <decui@microsoft.com>
To: "tglx@linutronix.de" <tglx@linutronix.de>,
"riel@surriel.com" <riel@surriel.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"jpoimboe@redhat.com" <jpoimboe@redhat.com>,
"luto@kernel.org" <luto@kernel.org>,
Stephen Hemminger <sthemmin@microsoft.com>,
Sasha Levin <Alexander.Levin@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
KY Srinivasan <kys@microsoft.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Michael Kelley <mikelley@microsoft.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>,
"apw@canonical.com" <apw@canonical.com>,
"olaf@aepfle.de" <olaf@aepfle.de>, vkuznets <vkuznets@redhat.com>,
"jasowang@redhat.com" <jasowang@redhat.com>,
Dexuan Cui <decui@microsoft.com>
Subject: [PATCH] smp: Do not warn if smp_call_function_single() is doing a self call.
Date: Fri, 12 Apr 2019 23:53:57 +0000 [thread overview]
Message-ID: <20190412235341.29379-1-decui@microsoft.com> (raw)
If smp_call_function_single() is calling the function for itself, it's safe
to run with irqs_disabled() == true.
I hit the warning because I'm in the below path in the .suspend callback of
a "syscore_ops" to support hibernation for a VM running on Hyper-V:
hv_synic_cleanup() ->
clockevents_unbind_device() ->
clockevents_unbind() ->
smp_call_function_single().
When the .suspend callback runs, only CPU0 is online and irqs_disabled() is
true.
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
kernel/smp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/smp.c b/kernel/smp.c
index f4cf1b0bb3b8..4fdf6a378def 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -288,7 +288,7 @@ int smp_call_function_single(int cpu, smp_call_func_t func, void *info,
* can't happen.
*/
WARN_ON_ONCE(cpu_online(this_cpu) && irqs_disabled()
- && !oops_in_progress);
+ && cpu != smp_processor_id() && !oops_in_progress);
csd = &csd_stack;
if (!wait) {
--
2.19.1
next reply other threads:[~2019-04-12 23:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-12 23:53 Dexuan Cui [this message]
2019-04-14 6:58 ` [PATCH] smp: Do not warn if smp_call_function_single() is doing a self call Vitaly Kuznetsov
2019-04-15 12:21 ` Peter Zijlstra
2019-04-15 23:39 ` Dexuan Cui
2019-04-16 9:31 ` Peter Zijlstra
2019-04-16 11:20 ` Vitaly Kuznetsov
2019-04-16 20:13 ` Thomas Gleixner
2019-04-17 23:50 ` Dexuan Cui
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