766c268bc6
dump_stack() implements its own cpu-reentrant spinning lock to best-effort serialize stack traces in the printk log. However, there are other functions (such as show_regs()) that can also benefit from this serialization. Move the cpu-reentrant spinning lock (cpu lock) into new helper functions printk_cpu_lock_irqsave()/printk_cpu_unlock_irqrestore() so that it is available for others as well. For !CONFIG_SMP the cpu lock is a NOP. Note that having multiple cpu locks in the system can easily lead to deadlock. Code needing a cpu lock should use the printk cpu lock, since the printk cpu lock could be acquired from any code and any context. Also note that it is not necessary for a cpu lock to disable interrupts. However, in upcoming work this cpu lock will be used for emergency tasks (for example, atomic consoles during kernel crashes) and any interruptions while holding the cpu lock should be avoided if possible. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> [pmladek@suse.com: Backported on top of 5.13-rc1.] Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20210617095051.4808-2-john.ogness@linutronix.de
99 lines
2.6 KiB
C
99 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Provide a default dump_stack() function for architectures
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* which don't implement their own.
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*/
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/smp.h>
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#include <linux/atomic.h>
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#include <linux/kexec.h>
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#include <linux/utsname.h>
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#include <linux/stop_machine.h>
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static char dump_stack_arch_desc_str[128];
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/**
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* dump_stack_set_arch_desc - set arch-specific str to show with task dumps
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* @fmt: printf-style format string
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* @...: arguments for the format string
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*
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* The configured string will be printed right after utsname during task
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* dumps. Usually used to add arch-specific system identifiers. If an
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* arch wants to make use of such an ID string, it should initialize this
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* as soon as possible during boot.
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*/
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void __init dump_stack_set_arch_desc(const char *fmt, ...)
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{
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va_list args;
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va_start(args, fmt);
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vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
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fmt, args);
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va_end(args);
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}
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/**
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* dump_stack_print_info - print generic debug info for dump_stack()
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* @log_lvl: log level
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*
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* Arch-specific dump_stack() implementations can use this function to
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* print out the same debug information as the generic dump_stack().
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*/
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void dump_stack_print_info(const char *log_lvl)
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{
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printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n",
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log_lvl, raw_smp_processor_id(), current->pid, current->comm,
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kexec_crash_loaded() ? "Kdump: loaded " : "",
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print_tainted(),
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init_utsname()->release,
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(int)strcspn(init_utsname()->version, " "),
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init_utsname()->version);
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if (dump_stack_arch_desc_str[0] != '\0')
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printk("%sHardware name: %s\n",
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log_lvl, dump_stack_arch_desc_str);
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print_worker_info(log_lvl, current);
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print_stop_info(log_lvl, current);
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}
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/**
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* show_regs_print_info - print generic debug info for show_regs()
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* @log_lvl: log level
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*
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* show_regs() implementations can use this function to print out generic
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* debug information.
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*/
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void show_regs_print_info(const char *log_lvl)
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{
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dump_stack_print_info(log_lvl);
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}
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static void __dump_stack(void)
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{
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dump_stack_print_info(KERN_DEFAULT);
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show_stack(NULL, NULL, KERN_DEFAULT);
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}
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/**
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* dump_stack - dump the current task information and its stack trace
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*
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* Architectures can override this implementation by implementing its own.
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*/
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asmlinkage __visible void dump_stack(void)
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{
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unsigned long flags;
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/*
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* Permit this cpu to perform nested stack dumps while serialising
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* against other CPUs
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*/
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printk_cpu_lock_irqsave(flags);
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__dump_stack();
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printk_cpu_unlock_irqrestore(flags);
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}
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EXPORT_SYMBOL(dump_stack);
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