From: Thomas Gleixner <tglx@linutronix.de> To: LKML <linux-kernel@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>, Sebastian Siewior <bigeasy@linutronix.de>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, "David S. Miller" <davem@davemloft.net>, Fenghua Yu <fenghua.yu@intel.com>, Herbert Xu <herbert@gondor.apana.org.au>, Lai Jiangshan <jiangshanlai@gmail.com>, Len Brown <lenb@kernel.org>, Michael Ellerman <mpe@ellerman.id.au>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Tejun Heo <tj@kernel.org>, Tony Luck <tony.luck@intel.com>, Viresh Kumar <viresh.kumar@linaro.org>, Paul Mackerras <paulus@samba.org>, linuxppc-dev@lists.ozlabs.org Subject: [patch 05/13] powerpc/smp: Replace open coded task affinity logic Date: Wed, 12 Apr 2017 22:07:31 +0200 [thread overview] Message-ID: <20170412201042.518053336@linutronix.de> (raw) In-Reply-To: 20170412200726.941336635@linutronix.de [-- Attachment #1: powerpc-smp--Use-work-function-instead-of-affinity-games.patch --] [-- Type: text/plain, Size: 2437 bytes --] Init task invokes smp_ops->setup_cpu() from smp_cpus_done(). Init task can run on any online CPU at this point, but the setup_cpu() callback requires to be invoked on the boot 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. That's actually not a problem in this context as neither CPU hotplug nor affinity settings can happen, but the access to task_struct::cpus_allowed is about to restricted. Replace it with a call to work_on_cpu_safe() which achieves the same result. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org --- arch/powerpc/kernel/smp.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -787,24 +787,21 @@ static struct sched_domain_topology_leve { NULL, }, }; -void __init smp_cpus_done(unsigned int max_cpus) +static __init long smp_setup_cpu_workfn(void *data __always_unused) { - cpumask_var_t old_mask; + smp_ops->setup_cpu(boot_cpuid); + return 0; +} - /* We want the setup_cpu() here to be called from CPU 0, but our - * init thread may have been "borrowed" by another CPU in the meantime - * se we pin us down to CPU 0 for a short while +void __init smp_cpus_done(unsigned int max_cpus) +{ + /* + * We want the setup_cpu() here to be called on the boot CPU, but + * init might run on any CPU, so make sure it's invoked on the boot + * CPU. */ - alloc_cpumask_var(&old_mask, GFP_NOWAIT); - cpumask_copy(old_mask, ¤t->cpus_allowed); - set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid)); - if (smp_ops && smp_ops->setup_cpu) - smp_ops->setup_cpu(boot_cpuid); - - set_cpus_allowed_ptr(current, old_mask); - - free_cpumask_var(old_mask); + work_on_cpu_safe(boot_cpuid, smp_setup_cpu_workfn, NULL); if (smp_ops && smp_ops->bringup_done) smp_ops->bringup_done(); @@ -812,7 +809,6 @@ void __init smp_cpus_done(unsigned int m dump_numa_cpu_topology(); set_sched_topology(powerpc_topology); - } #ifdef CONFIG_HOTPLUG_CPU
WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de> To: LKML <linux-kernel@vger.kernel.org> Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>, Sebastian Siewior <bigeasy@linutronix.de>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, "David S. Miller" <davem@davemloft.net>, Fenghua Yu <fenghua.yu@intel.com>, Herbert Xu <herbert@gondor.apana.org.au>, Lai Jiangshan <jiangshanlai@gmail.com>, Len Brown <lenb@kernel.org>, Michael Ellerman <mpe@ellerman.id.au>, "Rafael J. Wysocki" <rjw@rjwysocki.net>, Tejun Heo <tj@kernel.org>, Tony Luck <tony.luck@intel.com>, Viresh Kumar <viresh.kumar@linaro.org>, Paul Mackerras <paulus@samba.org>, linuxppc-dev@lists.ozlabs.org Subject: [patch 05/13] powerpc/smp: Replace open coded task affinity logic Date: Wed, 12 Apr 2017 22:07:31 +0200 [thread overview] Message-ID: <20170412201042.518053336@linutronix.de> (raw) In-Reply-To: 20170412200726.941336635@linutronix.de Init task invokes smp_ops->setup_cpu() from smp_cpus_done(). Init task can run on any online CPU at this point, but the setup_cpu() callback requires to be invoked on the boot 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. That's actually not a problem in this context as neither CPU hotplug nor affinity settings can happen, but the access to task_struct::cpus_allowed is about to restricted. Replace it with a call to work_on_cpu_safe() which achieves the same result. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: linuxppc-dev@lists.ozlabs.org --- arch/powerpc/kernel/smp.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -787,24 +787,21 @@ static struct sched_domain_topology_leve { NULL, }, }; -void __init smp_cpus_done(unsigned int max_cpus) +static __init long smp_setup_cpu_workfn(void *data __always_unused) { - cpumask_var_t old_mask; + smp_ops->setup_cpu(boot_cpuid); + return 0; +} - /* We want the setup_cpu() here to be called from CPU 0, but our - * init thread may have been "borrowed" by another CPU in the meantime - * se we pin us down to CPU 0 for a short while +void __init smp_cpus_done(unsigned int max_cpus) +{ + /* + * We want the setup_cpu() here to be called on the boot CPU, but + * init might run on any CPU, so make sure it's invoked on the boot + * CPU. */ - alloc_cpumask_var(&old_mask, GFP_NOWAIT); - cpumask_copy(old_mask, ¤t->cpus_allowed); - set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid)); - if (smp_ops && smp_ops->setup_cpu) - smp_ops->setup_cpu(boot_cpuid); - - set_cpus_allowed_ptr(current, old_mask); - - free_cpumask_var(old_mask); + work_on_cpu_safe(boot_cpuid, smp_setup_cpu_workfn, NULL); if (smp_ops && smp_ops->bringup_done) smp_ops->bringup_done(); @@ -812,7 +809,6 @@ void __init smp_cpus_done(unsigned int m dump_numa_cpu_topology(); set_sched_topology(powerpc_topology); - } #ifdef CONFIG_HOTPLUG_CPU
next prev parent reply other threads:[~2017-04-12 20:20 UTC|newest] Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-04-12 20:07 [patch 00/13] sched/treewide: Clean up various racy task affinity issues Thomas Gleixner 2017-04-12 20:07 ` [patch 01/13] ia64/topology: Remove cpus_allowed manipulation Thomas Gleixner 2017-04-12 20:07 ` Thomas Gleixner 2017-04-15 14:15 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 02/13] workqueue: Provide work_on_cpu_safe() Thomas Gleixner 2017-04-13 11:11 ` Dou Liyang 2017-04-13 21:28 ` Thomas Gleixner 2017-04-14 4:18 ` Tejun Heo 2017-04-14 8:54 ` Peter Zijlstra 2017-04-14 9:51 ` Thomas Gleixner 2017-04-14 9:56 ` Peter Zijlstra 2017-04-15 14:16 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 03/13] ia64/salinfo: Replace racy task affinity logic Thomas Gleixner 2017-04-12 20:07 ` Thomas Gleixner 2017-04-15 14:17 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 04/13] ia64/sn/hwperf: " Thomas Gleixner 2017-04-12 20:07 ` Thomas Gleixner 2017-04-12 20:53 ` [patch V 2 " Thomas Gleixner 2017-04-12 20:53 ` Thomas Gleixner 2017-04-15 14:17 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` Thomas Gleixner [this message] 2017-04-12 20:07 ` [patch 05/13] powerpc/smp: Replace open coded " Thomas Gleixner 2017-04-13 5:47 ` Michael Ellerman 2017-04-15 14:18 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 06/13] sparc/sysfs: Replace racy " Thomas Gleixner 2017-04-12 20:07 ` Thomas Gleixner 2017-04-13 1:52 ` David Miller 2017-04-13 1:52 ` David Miller 2017-04-13 8:17 ` [patch V2 " Thomas Gleixner 2017-04-13 8:17 ` Thomas Gleixner 2017-04-15 14:18 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 07/13] ACPI/processor: Fix error handling in __acpi_processor_start() Thomas Gleixner 2017-04-15 14:19 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 08/13] ACPI/processor: Replace racy task affinity logic Thomas Gleixner 2017-04-13 11:39 ` Peter Zijlstra 2017-04-13 12:01 ` Thomas Gleixner 2017-04-13 12:52 ` Peter Zijlstra 2017-04-15 14:19 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 09/13] cpufreq/ia64: " Thomas Gleixner 2017-04-12 20:55 ` [patch V2 " Thomas Gleixner 2017-04-15 14:20 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-13 2:42 ` [patch 09/13] " Viresh Kumar 2017-04-12 20:07 ` [patch 10/13] cpufreq/sh: " Thomas Gleixner 2017-04-13 2:46 ` Viresh Kumar 2017-04-15 14:20 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 11/13] cpufreq/sparc-us3: " Thomas Gleixner 2017-04-13 2:48 ` Viresh Kumar 2017-04-15 14:21 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-12 20:07 ` [patch 12/13] cpufreq/sparc-us2e: " Thomas Gleixner 2017-04-13 2:50 ` Viresh Kumar 2017-04-13 8:19 ` [patch V2 " Thomas Gleixner 2017-04-13 8:22 ` [patch V3 " Thomas Gleixner 2017-04-15 14:21 ` [tip:sched/core] " tip-bot for Thomas Gleixner 2017-04-13 14:50 ` [patch V2 12/13] " David Miller 2017-04-12 20:07 ` [patch 13/13] crypto: n2 - " Thomas Gleixner 2017-04-13 4:56 ` Herbert Xu 2017-04-13 8:20 ` [patch V2 " Thomas Gleixner 2017-04-13 14:51 ` David Miller 2017-04-15 14:22 ` [tip:sched/core] crypto: N2 " tip-bot for Thomas Gleixner 2017-04-13 9:02 ` [patch 00/13] sched/treewide: Clean up various racy task affinity issues Peter Zijlstra
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