printk: rename nmi.c and exported api
A preparation patch for printk_safe work. No functional change. - rename nmi.c to print_safe.c - add `printk_safe' prefix to some (which used both by printk-safe and printk-nmi) of the exported functions. Link: http://lkml.kernel.org/r/20161227141611.940-3-sergey.senozhatsky@gmail.com Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Calvin Owens <calvinowens@fb.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Peter Hurley <peter@hurleysoftware.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
parent
bd66a89249
commit
f92bac3b14
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@ -147,17 +147,17 @@ void early_printk(const char *s, ...) { }
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#endif
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#endif
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#ifdef CONFIG_PRINTK_NMI
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#ifdef CONFIG_PRINTK_NMI
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extern void printk_nmi_init(void);
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extern void printk_safe_init(void);
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extern void printk_nmi_enter(void);
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extern void printk_nmi_enter(void);
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extern void printk_nmi_exit(void);
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extern void printk_nmi_exit(void);
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extern void printk_nmi_flush(void);
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extern void printk_safe_flush(void);
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extern void printk_nmi_flush_on_panic(void);
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extern void printk_safe_flush_on_panic(void);
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#else
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#else
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static inline void printk_nmi_init(void) { }
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static inline void printk_safe_init(void) { }
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static inline void printk_nmi_enter(void) { }
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static inline void printk_nmi_enter(void) { }
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static inline void printk_nmi_exit(void) { }
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static inline void printk_nmi_exit(void) { }
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static inline void printk_nmi_flush(void) { }
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static inline void printk_safe_flush(void) { }
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static inline void printk_nmi_flush_on_panic(void) { }
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static inline void printk_safe_flush_on_panic(void) { }
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#endif /* PRINTK_NMI */
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#endif /* PRINTK_NMI */
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#ifdef CONFIG_PRINTK
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#ifdef CONFIG_PRINTK
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16
init/Kconfig
16
init/Kconfig
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@ -875,17 +875,19 @@ config LOG_CPU_MAX_BUF_SHIFT
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13 => 8 KB for each CPU
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13 => 8 KB for each CPU
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12 => 4 KB for each CPU
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12 => 4 KB for each CPU
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config NMI_LOG_BUF_SHIFT
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config PRINTK_SAFE_LOG_BUF_SHIFT
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int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
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int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
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range 10 21
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range 10 21
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default 13
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default 13
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depends on PRINTK_NMI
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depends on PRINTK
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help
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help
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Select the size of a per-CPU buffer where NMI messages are temporary
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Select the size of an alternate printk per-CPU buffer where messages
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stored. They are copied to the main log buffer in a safe context
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printed from usafe contexts are temporary stored. One example would
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to avoid a deadlock. The value defines the size as a power of 2.
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be NMI messages, another one - printk recursion. The messages are
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copied to the main log buffer in a safe context to avoid a deadlock.
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The value defines the size as a power of 2.
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NMI messages are rare and limited. The largest one is when
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Those messages are rare and limited. The largest one is when
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a backtrace is printed. It usually fits into 4KB. Select
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a backtrace is printed. It usually fits into 4KB. Select
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8KB if you want to be on the safe side.
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8KB if you want to be on the safe side.
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@ -580,7 +580,7 @@ asmlinkage __visible void __init start_kernel(void)
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timekeeping_init();
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timekeeping_init();
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time_init();
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time_init();
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sched_clock_postinit();
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sched_clock_postinit();
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printk_nmi_init();
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printk_safe_init();
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perf_event_init();
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perf_event_init();
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profile_init();
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profile_init();
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call_function_init();
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call_function_init();
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@ -916,7 +916,7 @@ void crash_kexec(struct pt_regs *regs)
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old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
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old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
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if (old_cpu == PANIC_CPU_INVALID) {
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if (old_cpu == PANIC_CPU_INVALID) {
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/* This is the 1st CPU which comes here, so go ahead. */
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/* This is the 1st CPU which comes here, so go ahead. */
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printk_nmi_flush_on_panic();
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printk_safe_flush_on_panic();
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__crash_kexec(regs);
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__crash_kexec(regs);
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/*
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/*
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@ -188,7 +188,7 @@ void panic(const char *fmt, ...)
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* Bypass the panic_cpu check and call __crash_kexec directly.
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* Bypass the panic_cpu check and call __crash_kexec directly.
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*/
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*/
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if (!_crash_kexec_post_notifiers) {
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if (!_crash_kexec_post_notifiers) {
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printk_nmi_flush_on_panic();
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printk_safe_flush_on_panic();
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__crash_kexec(NULL);
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__crash_kexec(NULL);
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/*
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/*
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@ -213,7 +213,7 @@ void panic(const char *fmt, ...)
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atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
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atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
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/* Call flush even twice. It tries harder with a single online CPU */
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/* Call flush even twice. It tries harder with a single online CPU */
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printk_nmi_flush_on_panic();
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printk_safe_flush_on_panic();
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kmsg_dump(KMSG_DUMP_PANIC);
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kmsg_dump(KMSG_DUMP_PANIC);
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/*
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/*
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@ -1,3 +1,3 @@
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obj-y = printk.o
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obj-y = printk.o
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obj-$(CONFIG_PRINTK_NMI) += nmi.o
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obj-$(CONFIG_PRINTK_NMI) += printk_safe.o
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obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o
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obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o
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@ -1,5 +1,5 @@
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/*
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/*
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* nmi.c - Safe printk in NMI context
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* printk_safe.c - Safe printk in NMI context
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*
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*
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* This program is free software; you can redistribute it and/or
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* modify it under the terms of the GNU General Public License
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@ -39,18 +39,18 @@
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* were handled or when IRQs are blocked.
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* were handled or when IRQs are blocked.
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*/
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*/
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DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
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DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
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static int printk_nmi_irq_ready;
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static int printk_safe_irq_ready;
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atomic_t nmi_message_lost;
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atomic_t nmi_message_lost;
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#define NMI_LOG_BUF_LEN ((1 << CONFIG_NMI_LOG_BUF_SHIFT) - \
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#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \
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sizeof(atomic_t) - sizeof(struct irq_work))
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sizeof(atomic_t) - sizeof(struct irq_work))
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struct nmi_seq_buf {
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struct printk_safe_seq_buf {
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atomic_t len; /* length of written data */
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atomic_t len; /* length of written data */
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struct irq_work work; /* IRQ work that flushes the buffer */
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struct irq_work work; /* IRQ work that flushes the buffer */
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unsigned char buffer[NMI_LOG_BUF_LEN];
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unsigned char buffer[SAFE_LOG_BUF_LEN];
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};
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};
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static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
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static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
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/*
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/*
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* Safe printk() for NMI context. It uses a per-CPU buffer to
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* Safe printk() for NMI context. It uses a per-CPU buffer to
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@ -60,7 +60,7 @@ static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
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*/
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*/
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static int vprintk_nmi(const char *fmt, va_list args)
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static int vprintk_nmi(const char *fmt, va_list args)
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{
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{
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struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
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struct printk_safe_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
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int add = 0;
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int add = 0;
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size_t len;
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size_t len;
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@ -91,7 +91,7 @@ again:
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goto again;
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goto again;
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/* Get flushed in a more safe context. */
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/* Get flushed in a more safe context. */
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if (add && printk_nmi_irq_ready) {
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if (add && printk_safe_irq_ready) {
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/* Make sure that IRQ work is really initialized. */
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/* Make sure that IRQ work is really initialized. */
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smp_rmb();
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smp_rmb();
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irq_work_queue(&s->work);
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irq_work_queue(&s->work);
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return add;
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return add;
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}
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}
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static void printk_nmi_flush_line(const char *text, int len)
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static void printk_safe_flush_line(const char *text, int len)
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{
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{
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/*
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/*
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* The buffers are flushed in NMI only on panic. The messages must
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* The buffers are flushed in NMI only on panic. The messages must
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@ -111,11 +111,10 @@ static void printk_nmi_flush_line(const char *text, int len)
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printk_deferred("%.*s", len, text);
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printk_deferred("%.*s", len, text);
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else
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else
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printk("%.*s", len, text);
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printk("%.*s", len, text);
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}
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}
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/* printk part of the temporary buffer line by line */
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/* printk part of the temporary buffer line by line */
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static int printk_nmi_flush_buffer(const char *start, size_t len)
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static int printk_safe_flush_buffer(const char *start, size_t len)
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{
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{
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const char *c, *end;
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const char *c, *end;
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bool header;
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bool header;
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@ -127,7 +126,7 @@ static int printk_nmi_flush_buffer(const char *start, size_t len)
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/* Print line by line. */
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/* Print line by line. */
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while (c < end) {
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while (c < end) {
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if (*c == '\n') {
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if (*c == '\n') {
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printk_nmi_flush_line(start, c - start + 1);
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printk_safe_flush_line(start, c - start + 1);
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start = ++c;
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start = ++c;
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header = true;
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header = true;
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continue;
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continue;
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continue;
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continue;
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}
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}
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printk_nmi_flush_line(start, c - start);
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printk_safe_flush_line(start, c - start);
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start = c++;
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start = c++;
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header = true;
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header = true;
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continue;
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continue;
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@ -154,8 +153,8 @@ static int printk_nmi_flush_buffer(const char *start, size_t len)
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if (start < end && !header) {
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if (start < end && !header) {
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static const char newline[] = KERN_CONT "\n";
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static const char newline[] = KERN_CONT "\n";
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printk_nmi_flush_line(start, end - start);
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printk_safe_flush_line(start, end - start);
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printk_nmi_flush_line(newline, strlen(newline));
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printk_safe_flush_line(newline, strlen(newline));
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}
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}
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return len;
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return len;
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@ -165,11 +164,12 @@ static int printk_nmi_flush_buffer(const char *start, size_t len)
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* Flush data from the associated per_CPU buffer. The function
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* Flush data from the associated per_CPU buffer. The function
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* can be called either via IRQ work or independently.
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* can be called either via IRQ work or independently.
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*/
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*/
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static void __printk_nmi_flush(struct irq_work *work)
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static void __printk_safe_flush(struct irq_work *work)
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{
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{
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static raw_spinlock_t read_lock =
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static raw_spinlock_t read_lock =
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__RAW_SPIN_LOCK_INITIALIZER(read_lock);
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__RAW_SPIN_LOCK_INITIALIZER(read_lock);
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struct nmi_seq_buf *s = container_of(work, struct nmi_seq_buf, work);
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struct printk_safe_seq_buf *s =
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container_of(work, struct printk_safe_seq_buf, work);
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unsigned long flags;
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unsigned long flags;
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size_t len;
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size_t len;
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int i;
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int i;
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* buffer size.
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* buffer size.
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*/
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*/
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if ((i && i >= len) || len > sizeof(s->buffer)) {
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if ((i && i >= len) || len > sizeof(s->buffer)) {
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const char *msg = "printk_nmi_flush: internal error\n";
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const char *msg = "printk_safe_flush: internal error\n";
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printk_nmi_flush_line(msg, strlen(msg));
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printk_safe_flush_line(msg, strlen(msg));
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len = 0;
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len = 0;
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}
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}
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/* Make sure that data has been written up to the @len */
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/* Make sure that data has been written up to the @len */
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smp_rmb();
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smp_rmb();
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i += printk_nmi_flush_buffer(s->buffer + i, len - i);
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i += printk_safe_flush_buffer(s->buffer + i, len - i);
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/*
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/*
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* Check that nothing has got added in the meantime and truncate
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* Check that nothing has got added in the meantime and truncate
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}
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}
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/**
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/**
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* printk_nmi_flush - flush all per-cpu nmi buffers.
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* printk_safe_flush - flush all per-cpu nmi buffers.
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*
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*
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* The buffers are flushed automatically via IRQ work. This function
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* The buffers are flushed automatically via IRQ work. This function
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* is useful only when someone wants to be sure that all buffers have
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* is useful only when someone wants to be sure that all buffers have
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* been flushed at some point.
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* been flushed at some point.
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*/
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*/
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void printk_nmi_flush(void)
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void printk_safe_flush(void)
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{
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{
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int cpu;
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int cpu;
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for_each_possible_cpu(cpu)
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for_each_possible_cpu(cpu)
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__printk_nmi_flush(&per_cpu(nmi_print_seq, cpu).work);
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__printk_safe_flush(&per_cpu(nmi_print_seq, cpu).work);
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}
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}
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/**
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/**
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* printk_nmi_flush_on_panic - flush all per-cpu nmi buffers when the system
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* printk_safe_flush_on_panic - flush all per-cpu nmi buffers when the system
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* goes down.
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* goes down.
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*
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*
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* Similar to printk_nmi_flush() but it can be called even in NMI context when
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* Similar to printk_safe_flush() but it can be called even in NMI context when
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* the system goes down. It does the best effort to get NMI messages into
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* the system goes down. It does the best effort to get NMI messages into
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* the main ring buffer.
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* the main ring buffer.
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*
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*
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* Note that it could try harder when there is only one CPU online.
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* Note that it could try harder when there is only one CPU online.
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*/
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*/
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void printk_nmi_flush_on_panic(void)
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void printk_safe_flush_on_panic(void)
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{
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{
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/*
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/*
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* Make sure that we could access the main ring buffer.
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* Make sure that we could access the main ring buffer.
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@ -259,25 +259,25 @@ void printk_nmi_flush_on_panic(void)
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raw_spin_lock_init(&logbuf_lock);
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raw_spin_lock_init(&logbuf_lock);
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}
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}
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printk_nmi_flush();
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printk_safe_flush();
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}
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}
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void __init printk_nmi_init(void)
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void __init printk_safe_init(void)
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{
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{
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int cpu;
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int cpu;
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for_each_possible_cpu(cpu) {
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for_each_possible_cpu(cpu) {
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struct nmi_seq_buf *s = &per_cpu(nmi_print_seq, cpu);
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struct printk_safe_seq_buf *s = &per_cpu(nmi_print_seq, cpu);
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init_irq_work(&s->work, __printk_nmi_flush);
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init_irq_work(&s->work, __printk_safe_flush);
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}
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}
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/* Make sure that IRQ works are initialized before enabling. */
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/* Make sure that IRQ works are initialized before enabling. */
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smp_wmb();
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smp_wmb();
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printk_nmi_irq_ready = 1;
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printk_safe_irq_ready = 1;
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/* Flush pending messages that did not have scheduled IRQ works. */
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/* Flush pending messages that did not have scheduled IRQ works. */
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printk_nmi_flush();
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printk_safe_flush();
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}
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}
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void printk_nmi_enter(void)
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void printk_nmi_enter(void)
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@ -77,7 +77,7 @@ void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
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* Force flush any remote buffers that might be stuck in IRQ context
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* Force flush any remote buffers that might be stuck in IRQ context
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* and therefore could not run their irq_work.
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* and therefore could not run their irq_work.
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*/
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*/
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printk_nmi_flush();
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printk_safe_flush();
|
||||||
|
|
||||||
clear_bit_unlock(0, &backtrace_flag);
|
clear_bit_unlock(0, &backtrace_flag);
|
||||||
put_cpu();
|
put_cpu();
|
||||||
|
|
Loading…
Reference in New Issue