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
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
omap-hdmi-audio.h
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* hdmi-audio.c -- OMAP4+ DSS HDMI audio support library
*
* Copyright (C) 2014 Texas Instruments Incorporated - https://www.ti.com
*
* Author: Jyri Sarha <jsarha@ti.com>
*/
#ifndef __OMAP_HDMI_AUDIO_H__
#define __OMAP_HDMI_AUDIO_H__
#include <linux/platform_data/omapdss.h>
struct omap_dss_audio {
struct snd_aes_iec958 *iec;
struct snd_cea_861_aud_if *cea;
};
struct omap_hdmi_audio_ops {
int (*audio_startup)(struct device *dev,
void (*abort_cb)(struct device *dev));
int (*audio_shutdown)(struct device *dev);
int (*audio_start)(struct device *dev);
void (*audio_stop)(struct device *dev);
int (*audio_config)(struct device *dev,
struct omap_dss_audio *dss_audio);
};
/* HDMI audio initalization data */
struct omap_hdmi_audio_pdata {
struct device *dev;
unsigned int version;
phys_addr_t audio_dma_addr;
const struct omap_hdmi_audio_ops *ops;
};
#endif /* __OMAP_HDMI_AUDIO_H__ */
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