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Revision 787252a10d9422f3058df9a4821f389e5326c440 authored by Nathan Lynch on 15 October 2021, 17:39:02 UTC, committed by Michael Ellerman on 20 October 2021, 10:38:01 UTC 
powerpc/smp: do not decrement idle task preempt count in CPU offline
 
With PREEMPT_COUNT=y, when a CPU is offlined and then onlined again, we
get:

BUG: scheduling while atomic: swapper/1/0/0x00000000
no locks held by swapper/1/0.
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.0-rc2+ #100
Call Trace:
 dump_stack_lvl+0xac/0x108
 __schedule_bug+0xac/0xe0
 __schedule+0xcf8/0x10d0
 schedule_idle+0x3c/0x70
 do_idle+0x2d8/0x4a0
 cpu_startup_entry+0x38/0x40
 start_secondary+0x2ec/0x3a0
 start_secondary_prolog+0x10/0x14

This is because powerpc's arch_cpu_idle_dead() decrements the idle task's
preempt count, for reasons explained in commit a7c2bb8279d2 ("powerpc:
Re-enable preemption before cpu_die()"), specifically "start_secondary()
expects a preempt_count() of 0."

However, since commit 2c669ef6979c ("powerpc/preempt: Don't touch the idle
task's preempt_count during hotplug") and commit f1a0a376ca0c ("sched/core:
Initialize the idle task with preemption disabled"), that justification no
longer holds.

The idle task isn't supposed to re-enable preemption, so remove the
vestigial preempt_enable() from the CPU offline path.

Tested with pseries and powernv in qemu, and pseries on PowerVM.

Fixes: 2c669ef6979c ("powerpc/preempt: Don't touch the idle task's preempt_count during hotplug")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211015173902.2278118-1-nathanl@linux.ibm.com
1 parent 496c5fe
Raw File
da7219.h 
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * da7219.h - DA7219 ASoC Codec Driver Platform Data
 *
 * Copyright (c) 2015 Dialog Semiconductor
 *
 * Author: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
 */

#ifndef __DA7219_PDATA_H
#define __DA7219_PDATA_H

/* Mic Bias */
enum da7219_micbias_voltage {
	DA7219_MICBIAS_1_6V = 0,
	DA7219_MICBIAS_1_8V,
	DA7219_MICBIAS_2_0V,
	DA7219_MICBIAS_2_2V,
	DA7219_MICBIAS_2_4V,
	DA7219_MICBIAS_2_6V,
};

/* Mic input type */
enum da7219_mic_amp_in_sel {
	DA7219_MIC_AMP_IN_SEL_DIFF = 0,
	DA7219_MIC_AMP_IN_SEL_SE_P,
	DA7219_MIC_AMP_IN_SEL_SE_N,
};

struct da7219_aad_pdata;

enum da7219_dai_clks {
	DA7219_DAI_WCLK_IDX = 0,
	DA7219_DAI_BCLK_IDX,
	DA7219_DAI_NUM_CLKS,
};

struct da7219_pdata {
	bool wakeup_source;

	const char *dai_clk_names[DA7219_DAI_NUM_CLKS];

	/* Mic */
	enum da7219_micbias_voltage micbias_lvl;
	enum da7219_mic_amp_in_sel mic_amp_in_sel;

	/* AAD */
	struct da7219_aad_pdata *aad_pdata;
};

#endif /* __DA7219_PDATA_H */
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