* [bug report] ARM: sun9i: smp: Support CPU/cluster power down and hotplugging for cpu1~7
@ 2019-05-14 10:04 Dan Carpenter
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From: Dan Carpenter @ 2019-05-14 10:04 UTC (permalink / raw)
To: wens; +Cc: linux-arm-kernel
Hello Chen-Yu Tsai,
The patch 7cbea6327e76: "ARM: sun9i: smp: Support CPU/cluster power
down and hotplugging for cpu1~7" from Jan 17, 2018, leads to the
following static checker warning:
arch/arm/mach-sunxi/mc_smp.c:581 sunxi_mc_smp_cpu_kill()
error: scheduling with locks held: 'spin_lock:boot_lock'
arch/arm/mach-sunxi/mc_smp.c
546 /* wait for CPU core to die and enter WFI */
547 count = TIMEOUT_USEC / POLL_USEC;
548 spin_lock_irq(&boot_lock);
^^^^^^^^^^^^^^^^^^^^^^^^^
Atomic context.
549 for (tries = 0; tries < count; tries++) {
550 spin_unlock_irq(&boot_lock);
551 usleep_range(POLL_USEC / 2, POLL_USEC);
552 spin_lock_irq(&boot_lock);
553
554 /*
555 * If the user turns off a bunch of cores at the same
556 * time, the kernel might call cpu_kill before some of
557 * them are ready. This is because boot_lock serializes
558 * both cpu_die and cpu_kill callbacks. Either one could
559 * run first. We should wait for cpu_die to complete.
560 */
561 if (sunxi_mc_smp_cpu_table[cluster][cpu])
562 continue;
563
564 reg = readl(cpucfg_base + CPUCFG_CX_STATUS(cluster));
565 if (reg & CPUCFG_CX_STATUS_STANDBYWFI(cpu))
566 break;
567 }
568
569 if (tries >= count) {
570 ret = ETIMEDOUT;
571 goto out;
572 }
573
574 /* power down CPU core */
575 sunxi_cpu_powerdown(cpu, cluster);
576
577 if (!sunxi_mc_smp_cluster_is_down(cluster))
578 goto out;
579
580 /* wait for cluster L2 WFI */
581 ret = readl_poll_timeout(cpucfg_base + CPUCFG_CX_STATUS(cluster), reg,
582 reg & CPUCFG_CX_STATUS_STANDBYWFIL2,
583 POLL_USEC, TIMEOUT_USEC);
^^^^^^^^^
This is 100. Use zero instead to avoid sleeping?
584 if (ret) {
585 /*
586 * Ignore timeout on the cluster. Leaving the cluster on
587 * will not affect system execution, just use a bit more
588 * power. But returning an error here will only confuse
589 * the user as the CPU has already been shutdown.
590 */
591 ret = 0;
592 goto out;
593 }
594
595 /* Power down cluster */
596 sunxi_cluster_powerdown(cluster);
597
598 out:
599 spin_unlock_irq(&boot_lock);
^^^^^^^^^
600 pr_debug("%s: cluster %u cpu %u powerdown: %d\n",
601 __func__, cluster, cpu, ret);
602 return !ret;
603 }
regards,
dan carpenter
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