Commit 1bd845bc authored Sep 08, 2017 by Mathias Krause Committed by Herbert Xu Oct 07, 2017

padata: set cpu_index of unused CPUs to -1

The parallel queue per-cpu data structure gets initialized only for CPUs
in the 'pcpu' CPU mask set. This is not sufficient as the reorder timer
may run on a different CPU and might wrongly decide it's the target CPU
for the next reorder item as per-cpu memory gets memset(0) and we might
be waiting for the first CPU in cpumask.pcpu, i.e. cpu_index 0.

Make the '__this_cpu_read(pd->pqueue->cpu_index) == next_queue->cpu_index'
compare in padata_get_next() fail in this case by initializing the
cpu_index member of all per-cpu parallel queues. Use -1 for unused ones.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

parent 5e1a6462

kernel/padata.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -384,8 +384,14 @@ static void padata_init_pqueues(struct parallel_data *pd)
		struct padata_parallel_queue *pqueue;

		cpu_index = 0;
		for_each_cpu(cpu, pd->cpumask.pcpu) {
		for_each_possible_cpu(cpu) {
		pqueue = per_cpu_ptr(pd->pqueue, cpu);

		if (!cpumask_test_cpu(cpu, pd->cpumask.pcpu)) {
		pqueue->cpu_index = -1;
		continue;
		}

		pqueue->pd = pd;
		pqueue->cpu_index = cpu_index;
		cpu_index++;

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