linux-kernel - [PATCH] Kick CPUS that might be sleeping in cpus_idle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1199911330.975.3.camel@localhost.localdomain>
Date:	Wed, 09 Jan 2008 15:42:10 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	"Brown, Len" <len.brown@...el.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	Adam Belay <abelay@...ell.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andi Kleen <ak@...e.de>
Subject: [PATCH] Kick CPUS that might be sleeping in cpus_idle_wait

This patch is different than the first patch I sent out.
This one just sends an IPI to all CPUS that don't check in after 1 sec.


Sometimes cpu_idle_wait gets stuck because it might miss CPUS that are
already in idle, have no tasks waiting to run and have no interrupts
going to them.  This is common on bootup when switching cpu idle
governors.

This patch gives those CPUS that don't check in an IPI kick.

Signed-off-by: Steven Rostedt <srostedt@...hat.com>
---
 arch/x86/kernel/process_32.c |   11 +++++++++++
 arch/x86/kernel/process_64.c |   11 +++++++++++
 2 files changed, 22 insertions(+)

Index: linux-compile-i386.git/arch/x86/kernel/process_32.c
===================================================================
--- linux-compile-i386.git.orig/arch/x86/kernel/process_32.c	2008-01-09 14:09:36.000000000 -0500
+++ linux-compile-i386.git/arch/x86/kernel/process_32.c	2008-01-09 14:09:45.000000000 -0500
@@ -204,6 +204,10 @@ void cpu_idle(void)
 	}
 }
 
+static void do_nothing(void *unused)
+{
+}
+
 void cpu_idle_wait(void)
 {
 	unsigned int cpu, this_cpu = get_cpu();
@@ -228,6 +232,13 @@ void cpu_idle_wait(void)
 				cpu_clear(cpu, map);
 		}
 		cpus_and(map, map, cpu_online_map);
+		/*
+		 * We waited 1 sec, if a CPU still did not call idle
+		 * it may be because it is in idle and not waking up
+		 * because it has nothing to do.
+		 * Give all the remaining CPUS a kick.
+		 */
+		smp_call_function_mask(map, do_nothing, 0, 0);
 	} while (!cpus_empty(map));
 
 	set_cpus_allowed(current, tmp);
Index: linux-compile-i386.git/arch/x86/kernel/process_64.c
===================================================================
--- linux-compile-i386.git.orig/arch/x86/kernel/process_64.c	2008-01-09 14:09:36.000000000 -0500
+++ linux-compile-i386.git/arch/x86/kernel/process_64.c	2008-01-09 15:17:20.000000000 -0500
@@ -135,6 +135,10 @@ static void poll_idle (void)
 	cpu_relax();
 }
 
+static void do_nothing(void *unused)
+{
+}
+
 void cpu_idle_wait(void)
 {
 	unsigned int cpu, this_cpu = get_cpu();
@@ -160,6 +164,13 @@ void cpu_idle_wait(void)
 				cpu_clear(cpu, map);
 		}
 		cpus_and(map, map, cpu_online_map);
+		/*
+		 * We waited 1 sec, if a CPU still did not call idle
+		 * it may be because it is in idle and not waking up
+		 * because it has nothing to do.
+		 * Give all the remaining CPUS a kick.
+		 */
+		smp_call_function_mask(map, do_nothing, 0, 0);
 	} while (!cpus_empty(map));
 
 	set_cpus_allowed(current, tmp);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/