Revision b90d72a6bfdb5e5c62cd223a8cdf4045bfbcb94d authored by Will Deacon on 12 January 2021, 22:18:55 UTC, committed by Catalin Marinas on 13 January 2021, 15:08:41 UTC
This reverts commit 367c820ef08082e68df8a3bc12e62393af21e4b5. lockup_detector_init() makes heavy use of per-cpu variables and must be called with preemption disabled. Usually, it's handled early during boot in kernel_init_freeable(), before SMP has been initialised. Since we do not know whether or not our PMU interrupt can be signalled as an NMI until considerably later in the boot process, the Arm PMU driver attempts to re-initialise the lockup detector off the back of a device_initcall(). Unfortunately, this is called from preemptible context and results in the following splat: | BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1 | caller is debug_smp_processor_id+0x20/0x2c | CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.10.0+ #276 | Hardware name: linux,dummy-virt (DT) | Call trace: | dump_backtrace+0x0/0x3c0 | show_stack+0x20/0x6c | dump_stack+0x2f0/0x42c | check_preemption_disabled+0x1cc/0x1dc | debug_smp_processor_id+0x20/0x2c | hardlockup_detector_event_create+0x34/0x18c | hardlockup_detector_perf_init+0x2c/0x134 | watchdog_nmi_probe+0x18/0x24 | lockup_detector_init+0x44/0xa8 | armv8_pmu_driver_init+0x54/0x78 | do_one_initcall+0x184/0x43c | kernel_init_freeable+0x368/0x380 | kernel_init+0x1c/0x1cc | ret_from_fork+0x10/0x30 Rather than bodge this with raw_smp_processor_id() or randomly disabling preemption, simply revert the culprit for now until we figure out how to do this properly. Reported-by: Lecopzer Chen <lecopzer.chen@mediatek.com> Signed-off-by: Will Deacon <will@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Alexandru Elisei <alexandru.elisei@arm.com> Link: https://lore.kernel.org/r/20201221162249.3119-1-lecopzer.chen@mediatek.com Link: https://lore.kernel.org/r/20210112221855.10666-1-will@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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seq_oss.h
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef __SOUND_SEQ_OSS_H
#define __SOUND_SEQ_OSS_H
/*
* OSS compatible sequencer driver
*
* Copyright (C) 1998,99 Takashi Iwai
*/
#include <sound/asequencer.h>
#include <sound/seq_kernel.h>
/*
* argument structure for synthesizer operations
*/
struct snd_seq_oss_arg {
/* given by OSS sequencer */
int app_index; /* application unique index */
int file_mode; /* file mode - see below */
int seq_mode; /* sequencer mode - see below */
/* following must be initialized in open callback */
struct snd_seq_addr addr; /* opened port address */
void *private_data; /* private data for lowlevel drivers */
/* note-on event passing mode: initially given by OSS seq,
* but configurable by drivers - see below
*/
int event_passing;
};
/*
* synthesizer operation callbacks
*/
struct snd_seq_oss_callback {
struct module *owner;
int (*open)(struct snd_seq_oss_arg *p, void *closure);
int (*close)(struct snd_seq_oss_arg *p);
int (*ioctl)(struct snd_seq_oss_arg *p, unsigned int cmd, unsigned long arg);
int (*load_patch)(struct snd_seq_oss_arg *p, int format, const char __user *buf, int offs, int count);
int (*reset)(struct snd_seq_oss_arg *p);
int (*raw_event)(struct snd_seq_oss_arg *p, unsigned char *data);
};
/* flag: file_mode */
#define SNDRV_SEQ_OSS_FILE_ACMODE 3
#define SNDRV_SEQ_OSS_FILE_READ 1
#define SNDRV_SEQ_OSS_FILE_WRITE 2
#define SNDRV_SEQ_OSS_FILE_NONBLOCK 4
/* flag: seq_mode */
#define SNDRV_SEQ_OSS_MODE_SYNTH 0
#define SNDRV_SEQ_OSS_MODE_MUSIC 1
/* flag: event_passing */
#define SNDRV_SEQ_OSS_PROCESS_EVENTS 0 /* key == 255 is processed as velocity change */
#define SNDRV_SEQ_OSS_PASS_EVENTS 1 /* pass all events to callback */
#define SNDRV_SEQ_OSS_PROCESS_KEYPRESS 2 /* key >= 128 will be processed as key-pressure */
/* default control rate: fixed */
#define SNDRV_SEQ_OSS_CTRLRATE 100
/* default max queue length: configurable by module option */
#define SNDRV_SEQ_OSS_MAX_QLEN 1024
/*
* data pointer to snd_seq_register_device
*/
struct snd_seq_oss_reg {
int type;
int subtype;
int nvoices;
struct snd_seq_oss_callback oper;
void *private_data;
};
/* device id */
#define SNDRV_SEQ_DEV_ID_OSS "seq-oss"
#endif /* __SOUND_SEQ_OSS_H */
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