genirq/matrix: Deal with the sillyness of for_each_cpu() on UP
Most of the CPU mask operations behave the same way, but for_each_cpu() and it's variants ignore the cpumask argument and claim that CPU0 is always in the mask. This is historical, inconsistent and annoying behaviour. The matrix allocator uses for_each_cpu() and can be called on UP with an empty cpumask. The calling code does not expect that this succeeds but until commite027fffff7
("x86/irq: Unbreak interrupt affinity setting") this went unnoticed. That commit added a WARN_ON() to catch cases which move an interrupt from one vector to another on the same CPU. The warning triggers on UP. Add a check for the cpumask being empty to prevent this. Fixes:2f75d9e1c9
("genirq: Implement bitmap matrix allocator") Reported-by: kernel test robot <rong.a.chen@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org
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e027fffff7
Коммит
784a083037
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@ -380,6 +380,13 @@ int irq_matrix_alloc(struct irq_matrix *m, const struct cpumask *msk,
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unsigned int cpu, bit;
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struct cpumap *cm;
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/*
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* Not required in theory, but matrix_find_best_cpu() uses
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* for_each_cpu() which ignores the cpumask on UP .
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*/
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if (cpumask_empty(msk))
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return -EINVAL;
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cpu = matrix_find_best_cpu(m, msk);
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if (cpu == UINT_MAX)
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return -ENOSPC;
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