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Groups > linux.kernel > #1622805

[patch V2 12/13] cpufreq/sparc-us2e: Replace racy task affinity logic

From Thomas Gleixner <tglx@linutronix.de>
Newsgroups linux.kernel
Subject [patch V2 12/13] cpufreq/sparc-us2e: Replace racy task affinity logic
Date 2017-04-13 10:20 +0200
Message-ID <tvI8W-cb-5@gated-at.bofh.it> (permalink)
References <tvx3P-QV-3@gated-at.bofh.it> <tvx3P-QV-13@gated-at.bofh.it>
Organization linux.* mail to news gateway

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spu_queue_register() needs to invoke setup functions on a particular
CPU. This is achieved by temporarily setting the affinity of the
calling user space thread to the requested CPU and reset it to the original
affinity afterwards.

That's racy vs. CPU hotplug and concurrent affinity settings for that
thread resulting in code executing on the wrong CPU and overwriting the
new affinity setting.

Replace it by using work_on_cpu_safe() which guarantees to run the code on
the requested CPU or to fail in case the CPU is offline.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
---

V2: Fixup build-bot complaint

 drivers/crypto/n2_core.c |   31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

--- a/drivers/crypto/n2_core.c
+++ b/drivers/crypto/n2_core.c
@@ -65,6 +65,11 @@ struct spu_queue {
 	struct list_head	list;
 };
 
+struct spu_qreg {
+	struct spu_queue	*queue;
+	unsigned long		type;
+};
+
 static struct spu_queue **cpu_to_cwq;
 static struct spu_queue **cpu_to_mau;
 
@@ -1631,31 +1636,27 @@ static void queue_cache_destroy(void)
 	kmem_cache_destroy(queue_cache[HV_NCS_QTYPE_CWQ - 1]);
 }
 
-static int spu_queue_register(struct spu_queue *p, unsigned long q_type)
+static long spu_queue_register_workfn(void *arg)
 {
-	cpumask_var_t old_allowed;
+	struct spu_qreg *qr = arg;
+	struct spu_queue *p = qr->queue;
+	unsigned long q_type = qr->type;
 	unsigned long hv_ret;
 
-	if (cpumask_empty(&p->sharing))
-		return -EINVAL;
-
-	if (!alloc_cpumask_var(&old_allowed, GFP_KERNEL))
-		return -ENOMEM;
-
-	cpumask_copy(old_allowed, &current->cpus_allowed);
-
-	set_cpus_allowed_ptr(current, &p->sharing);
-
 	hv_ret = sun4v_ncs_qconf(q_type, __pa(p->q),
 				 CWQ_NUM_ENTRIES, &p->qhandle);
 	if (!hv_ret)
 		sun4v_ncs_sethead_marker(p->qhandle, 0);
 
-	set_cpus_allowed_ptr(current, old_allowed);
+	return hv_ret ? -EINVAL : 0;
+}
 
-	free_cpumask_var(old_allowed);
+static int spu_queue_register(struct spu_queue *p, unsigned long q_type)
+{
+	int cpu = cpumask_any_and(&p->sharing, cpu_online_mask);
+	struct spu_qreg qr = { .queue = p, .type = q_type };
 
-	return (hv_ret ? -EINVAL : 0);
+	return work_on_cpu_safe(cpu, spu_queue_register_workfn, &qr);
 }
 
 static int spu_queue_setup(struct spu_queue *p)

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Thread

[patch 00/13] sched/treewide: Clean up various racy task affinity  issues Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
  [patch 12/13] cpufreq/sparc-us2e: Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    Re: [patch 12/13] cpufreq/sparc-us2e: Replace racy task affinity  logic Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-13 05:00 +0200
    [patch V2 12/13] cpufreq/sparc-us2e: Replace racy task affinity  logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-13 10:20 +0200
      [patch V3 12/13] cpufreq/sparc-us2e: Replace racy task affinity  logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-13 10:30 +0200
        [tip:sched/core] cpufreq/sparc-us2e: Replace racy task affinity  logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
      Re: [patch V2 12/13] cpufreq/sparc-us2e: Replace racy task  affinity logic David Miller <davem@davemloft.net> - 2017-04-13 17:00 +0200
  [patch 03/13] ia64/salinfo: Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    [tip:sched/core] ia64/salinfo: Replace racy task affinity logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  [patch 04/13] ia64/sn/hwperf: Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    [patch V 2 04/13] ia64/sn/hwperf: Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 23:00 +0200
      [tip:sched/core] ia64/sn/hwperf: Replace racy task affinity logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  [patch 11/13] cpufreq/sparc-us3: Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    Re: [patch 11/13] cpufreq/sparc-us3: Replace racy task affinity logic Viresh Kumar <viresh.kumar@linaro.org> - 2017-04-13 04:50 +0200
    [tip:sched/core] cpufreq/sparc-us3: Replace racy task affinity  logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  [patch 01/13] ia64/topology: Remove cpus_allowed manipulation Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    [tip:sched/core] ia64/topology: Remove cpus_allowed manipulation tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  [patch 07/13] ACPI/processor: Fix error handling in  __acpi_processor_start() Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    [tip:sched/core] ACPI/processor: Fix error handling in  __acpi_processor_start() tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  [patch 08/13] ACPI/processor: Replace racy task affinity logic. Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    Re: [patch 08/13] ACPI/processor: Replace racy task affinity logic. Peter Zijlstra <peterz@infradead.org> - 2017-04-13 13:50 +0200
      Re: [patch 08/13] ACPI/processor: Replace racy task affinity  logic. Thomas Gleixner <tglx@linutronix.de> - 2017-04-13 14:10 +0200
        Re: [patch 08/13] ACPI/processor: Replace racy task affinity logic. Peter Zijlstra <peterz@infradead.org> - 2017-04-13 15:00 +0200
    [tip:sched/core] ACPI/processor: Replace racy task affinity logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  [patch 13/13] crypto: n2 - Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    Re: [patch 13/13] crypto: n2 - Replace racy task affinity logic Herbert Xu <herbert@gondor.apana.org.au> - 2017-04-13 07:40 +0200
    [patch V2 13/13] crypto: n2 - Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-13 10:30 +0200
      Re: [patch V2 13/13] crypto: n2 - Replace racy task affinity logic David Miller <davem@davemloft.net> - 2017-04-13 17:00 +0200
      [tip:sched/core] crypto: N2 - Replace racy task affinity logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:40 +0200
  [patch 05/13] powerpc/smp: Replace open coded task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    Re: [patch 05/13] powerpc/smp: Replace open coded task affinity logic Michael Ellerman <mpe@ellerman.id.au> - 2017-04-13 07:50 +0200
    [tip:sched/core] powerpc/smp: Replace open coded task affinity  logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  [patch 06/13] sparc/sysfs: Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    Re: [patch 06/13] sparc/sysfs: Replace racy task affinity logic David Miller <davem@davemloft.net> - 2017-04-13 04:00 +0200
      [patch V2 06/13] sparc/sysfs: Replace racy task affinity logic Thomas Gleixner <tglx@linutronix.de> - 2017-04-13 10:20 +0200
        [tip:sched/core] sparc/sysfs: Replace racy task affinity logic tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:20 +0200
  [patch 02/13] workqueue: Provide work_on_cpu_safe() Thomas Gleixner <tglx@linutronix.de> - 2017-04-12 22:30 +0200
    Re: [patch 02/13] workqueue: Provide work_on_cpu_safe() Dou Liyang <douly.fnst@cn.fujitsu.com> - 2017-04-13 13:20 +0200
      Re: [patch 02/13] workqueue: Provide work_on_cpu_safe() Thomas Gleixner <tglx@linutronix.de> - 2017-04-13 23:30 +0200
    Re: [patch 02/13] workqueue: Provide work_on_cpu_safe() Tejun Heo <tj@kernel.org> - 2017-04-14 06:20 +0200
    Re: [patch 02/13] workqueue: Provide work_on_cpu_safe() Peter Zijlstra <peterz@infradead.org> - 2017-04-14 11:00 +0200
      Re: [patch 02/13] workqueue: Provide work_on_cpu_safe() Thomas Gleixner <tglx@linutronix.de> - 2017-04-14 12:00 +0200
        Re: [patch 02/13] workqueue: Provide work_on_cpu_safe() Peter Zijlstra <peterz@infradead.org> - 2017-04-14 12:00 +0200
    [tip:sched/core] workqueue: Provide work_on_cpu_safe() tip-bot for Thomas Gleixner <tipbot@zytor.com> - 2017-04-15 16:30 +0200
  Re: [patch 00/13] sched/treewide: Clean up various racy task  affinity issues Peter Zijlstra <peterz@infradead.org> - 2017-04-13 11:10 +0200

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