Files
linux/include/linux/panic.h
Jinchao Wang d0d9c72355 panic: introduce helper functions for panic state
Patch series "panic: introduce panic status function family", v2.

This series introduces a family of helper functions to manage panic state
and updates existing code to use them.

Before this series, panic state helpers were scattered and inconsistent. 
For example, panic_in_progress() was defined in printk/printk.c, not in
panic.c or panic.h.  As a result, developers had to look in unexpected
places to understand or re-use panic state logic.  Other checks were open-
coded, duplicating logic across panic, crash, and watchdog paths.

The new helpers centralize the functionality in panic.c/panic.h:
  - panic_try_start()
  - panic_reset()
  - panic_in_progress()
  - panic_on_this_cpu()
  - panic_on_other_cpu()

Patches 1–8 add the helpers and convert panic/crash and printk/nbcon
code to use them.

Patch 9 fixes a bug in the watchdog subsystem by skipping checks when a
panic is in progress, avoiding interference with the panic CPU.

Together, this makes panic state handling simpler, more discoverable, and
more robust.


This patch (of 9):

This patch introduces four new helper functions to abstract the management
of the panic_cpu variable.  These functions will be used in subsequent
patches to refactor existing code.

The direct use of panic_cpu can be error-prone and ambiguous, as it
requires manual checks to determine which CPU is handling the panic.  The
new helpers clarify intent:

panic_try_start():
Atomically sets the current CPU as the panicking CPU.

panic_reset():
Reset panic_cpu to PANIC_CPU_INVALID.

panic_in_progress():
Checks if a panic has been triggered.

panic_on_this_cpu():
Returns true if the current CPU is the panic originator.

panic_on_other_cpu():
Returns true if a panic is on another CPU.

This change lays the groundwork for improved code readability
and robustness in the panic handling subsystem.

Link: https://lkml.kernel.org/r/20250825022947.1596226-1-wangjinchao600@gmail.com
Link: https://lkml.kernel.org/r/20250825022947.1596226-2-wangjinchao600@gmail.com
Signed-off-by: Jinchao Wang <wangjinchao600@gmail.com>
Cc: Anna Schumaker <anna.schumaker@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Kees Cook <kees@kernel.org>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Luo Gengkun <luogengkun@huaweicloud.com>
Cc: Max Kellermann <max.kellermann@ionos.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: oushixiong <oushixiong@kylinos.cn>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Qianqiang Liu <qianqiang.liu@163.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Yury Norov (NVIDIA) <yury.norov@gmail.com>b
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-09-13 17:32:51 -07:00

107 lines
3.0 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PANIC_H
#define _LINUX_PANIC_H
#include <linux/compiler_attributes.h>
#include <linux/stdarg.h>
#include <linux/types.h>
struct pt_regs;
extern long (*panic_blink)(int state);
__printf(1, 2)
void panic(const char *fmt, ...) __noreturn __cold;
__printf(1, 0)
void vpanic(const char *fmt, va_list args) __noreturn __cold;
void nmi_panic(struct pt_regs *regs, const char *msg);
void check_panic_on_warn(const char *origin);
extern void oops_enter(void);
extern void oops_exit(void);
extern bool oops_may_print(void);
extern bool panic_triggering_all_cpu_backtrace;
extern int panic_timeout;
extern unsigned long panic_print;
extern int panic_on_oops;
extern int panic_on_warn;
extern unsigned long panic_on_taint;
extern bool panic_on_taint_nousertaint;
extern int sysctl_panic_on_stackoverflow;
extern bool crash_kexec_post_notifiers;
extern void __stack_chk_fail(void);
void abort(void);
/*
* panic_cpu is used for synchronizing panic() and crash_kexec() execution. It
* holds a CPU number which is executing panic() currently. A value of
* PANIC_CPU_INVALID means no CPU has entered panic() or crash_kexec().
*/
extern atomic_t panic_cpu;
#define PANIC_CPU_INVALID -1
bool panic_try_start(void);
void panic_reset(void);
bool panic_in_progress(void);
bool panic_on_this_cpu(void);
bool panic_on_other_cpu(void);
/*
* Only to be used by arch init code. If the user over-wrote the default
* CONFIG_PANIC_TIMEOUT, honor it.
*/
static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
{
if (panic_timeout == arch_default_timeout)
panic_timeout = timeout;
}
/* This cannot be an enum because some may be used in assembly source. */
#define TAINT_PROPRIETARY_MODULE 0
#define TAINT_FORCED_MODULE 1
#define TAINT_CPU_OUT_OF_SPEC 2
#define TAINT_FORCED_RMMOD 3
#define TAINT_MACHINE_CHECK 4
#define TAINT_BAD_PAGE 5
#define TAINT_USER 6
#define TAINT_DIE 7
#define TAINT_OVERRIDDEN_ACPI_TABLE 8
#define TAINT_WARN 9
#define TAINT_CRAP 10
#define TAINT_FIRMWARE_WORKAROUND 11
#define TAINT_OOT_MODULE 12
#define TAINT_UNSIGNED_MODULE 13
#define TAINT_SOFTLOCKUP 14
#define TAINT_LIVEPATCH 15
#define TAINT_AUX 16
#define TAINT_RANDSTRUCT 17
#define TAINT_TEST 18
#define TAINT_FWCTL 19
#define TAINT_FLAGS_COUNT 20
#define TAINT_FLAGS_MAX ((1UL << TAINT_FLAGS_COUNT) - 1)
struct taint_flag {
char c_true; /* character printed when tainted */
char c_false; /* character printed when not tainted */
bool module; /* also show as a per-module taint flag */
const char *desc; /* verbose description of the set taint flag */
};
extern const struct taint_flag taint_flags[TAINT_FLAGS_COUNT];
enum lockdep_ok {
LOCKDEP_STILL_OK,
LOCKDEP_NOW_UNRELIABLE,
};
extern const char *print_tainted(void);
extern const char *print_tainted_verbose(void);
extern void add_taint(unsigned flag, enum lockdep_ok);
extern int test_taint(unsigned flag);
extern unsigned long get_taint(void);
#endif /* _LINUX_PANIC_H */