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https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux-stable.git
synced 2025-11-04 07:44:51 +10:00
4ab0a9409a
Impact: fix debug_smp_processor_id() for CONFIG_CPUMASK_OFFSTACK=y The scheduler now uses the new cpumask API, which deals up to nr_cpumask_bits, whereas the API used NR_CPUS bits. If CONFIG_CPUMASK_OFFSTACK=y these two are not equal, so the top bits are undefined. Leading to bug 12518 "BUG: using smp_processor_id() in preemptible [00000000] code: dellWirelessCtl/..." The fix is simple: use the modern API in the check. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
/*
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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/module.h>
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#include <linux/kallsyms.h>
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#include <linux/sched.h>
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notrace unsigned int debug_smp_processor_id(void)
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{
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unsigned long preempt_count = preempt_count();
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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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/*
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* Kernel threads bound to a single CPU can safely use
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* smp_processor_id():
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*/
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if (cpumask_equal(¤t->cpus_allowed, cpumask_of(this_cpu)))
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goto out;
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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_RUNNING)
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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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if (!printk_ratelimit())
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goto out_enable;
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printk(KERN_ERR "BUG: using smp_processor_id() in preemptible [%08x] "
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"code: %s/%d\n",
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preempt_count() - 1, current->comm, current->pid);
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print_symbol("caller is %s\n", (long)__builtin_return_address(0));
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dump_stack();
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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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EXPORT_SYMBOL(debug_smp_processor_id);
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