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https://github.com/torvalds/linux
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570a752b7a
is_percpu_thread() more elegantly handles SMP vs UP, and further checks the presence of PF_NO_SETAFFINITY. This lets us catch cases where check_preemption_disabled() can race with a concurrent sched_setaffinity(). Signed-off-by: Yejune Deng <yejune.deng@gmail.com> [Amended changelog] Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210510151024.2448573-3-valentin.schneider@arm.com
68 lines
1.4 KiB
C
68 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* lib/smp_processor_id.c
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*
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* DEBUG_PREEMPT variant of smp_processor_id().
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*/
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#include <linux/export.h>
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#include <linux/kprobes.h>
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#include <linux/sched.h>
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noinstr static
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unsigned int check_preemption_disabled(const char *what1, const char *what2)
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{
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int this_cpu = raw_smp_processor_id();
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if (likely(preempt_count()))
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goto out;
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if (irqs_disabled())
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goto out;
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if (is_percpu_thread())
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goto out;
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#ifdef CONFIG_SMP
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if (current->migration_disabled)
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goto out;
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#endif
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/*
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* It is valid to assume CPU-locality during early bootup:
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*/
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if (system_state < SYSTEM_SCHEDULING)
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goto out;
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/*
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* Avoid recursion:
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*/
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preempt_disable_notrace();
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instrumentation_begin();
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if (!printk_ratelimit())
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goto out_enable;
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printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
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what1, what2, preempt_count() - 1, current->comm, current->pid);
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printk("caller is %pS\n", __builtin_return_address(0));
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dump_stack();
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instrumentation_end();
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out_enable:
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preempt_enable_no_resched_notrace();
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out:
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return this_cpu;
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}
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noinstr unsigned int debug_smp_processor_id(void)
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{
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return check_preemption_disabled("smp_processor_id", "");
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}
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EXPORT_SYMBOL(debug_smp_processor_id);
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noinstr void __this_cpu_preempt_check(const char *op)
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{
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check_preemption_disabled("__this_cpu_", op);
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}
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EXPORT_SYMBOL(__this_cpu_preempt_check);
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