diff options
| -rw-r--r-- | include/linux/printk.h | 12 | ||||
| -rw-r--r-- | init/Kconfig | 16 | ||||
| -rw-r--r-- | init/main.c | 2 | ||||
| -rw-r--r-- | kernel/kexec_core.c | 2 | ||||
| -rw-r--r-- | kernel/panic.c | 4 | ||||
| -rw-r--r-- | kernel/printk/Makefile | 2 | ||||
| -rw-r--r-- | kernel/printk/printk_safe.c (renamed from kernel/printk/nmi.c) | 64 | ||||
| -rw-r--r-- | lib/nmi_backtrace.c | 2 |
8 files changed, 53 insertions, 51 deletions
diff --git a/include/linux/printk.h b/include/linux/printk.h index 3472cc6b7a60..37e933eeffb2 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -147,17 +147,17 @@ void early_printk(const char *s, ...) { } #endif #ifdef CONFIG_PRINTK_NMI -extern void printk_nmi_init(void); +extern void printk_safe_init(void); extern void printk_nmi_enter(void); extern void printk_nmi_exit(void); -extern void printk_nmi_flush(void); -extern void printk_nmi_flush_on_panic(void); +extern void printk_safe_flush(void); +extern void printk_safe_flush_on_panic(void); #else -static inline void printk_nmi_init(void) { } +static inline void printk_safe_init(void) { } static inline void printk_nmi_enter(void) { } static inline void printk_nmi_exit(void) { } -static inline void printk_nmi_flush(void) { } -static inline void printk_nmi_flush_on_panic(void) { } +static inline void printk_safe_flush(void) { } +static inline void printk_safe_flush_on_panic(void) { } #endif /* PRINTK_NMI */ #ifdef CONFIG_PRINTK diff --git a/init/Kconfig b/init/Kconfig index 223b734abccd..760b7d0bc9d7 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -875,17 +875,19 @@ config LOG_CPU_MAX_BUF_SHIFT 13 => 8 KB for each CPU 12 => 4 KB for each CPU -config NMI_LOG_BUF_SHIFT - int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)" +config PRINTK_SAFE_LOG_BUF_SHIFT + int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)" range 10 21 default 13 - depends on PRINTK_NMI + depends on PRINTK help - Select the size of a per-CPU buffer where NMI messages are temporary - stored. They are copied to the main log buffer in a safe context - to avoid a deadlock. The value defines the size as a power of 2. + Select the size of an alternate printk per-CPU buffer where messages + printed from usafe contexts are temporary stored. One example would + be NMI messages, another one - printk recursion. The messages are + copied to the main log buffer in a safe context to avoid a deadlock. + The value defines the size as a power of 2. - NMI messages are rare and limited. The largest one is when + Those messages are rare and limited. The largest one is when a backtrace is printed. It usually fits into 4KB. Select 8KB if you want to be on the safe side. diff --git a/init/main.c b/init/main.c index b0c9d6facef9..b4ca17d9bdeb 100644 --- a/init/main.c +++ b/init/main.c @@ -580,7 +580,7 @@ asmlinkage __visible void __init start_kernel(void) timekeeping_init(); time_init(); sched_clock_postinit(); - printk_nmi_init(); + printk_safe_init(); perf_event_init(); profile_init(); call_function_init(); diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 5617cc412444..14bb9eb76665 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -916,7 +916,7 @@ void crash_kexec(struct pt_regs *regs) old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu); if (old_cpu == PANIC_CPU_INVALID) { /* This is the 1st CPU which comes here, so go ahead. */ - printk_nmi_flush_on_panic(); + printk_safe_flush_on_panic(); __crash_kexec(regs); /* diff --git a/kernel/panic.c b/kernel/panic.c index c51edaa04fce..8c8efcd310e7 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -188,7 +188,7 @@ void panic(const char *fmt, ...) * Bypass the panic_cpu check and call __crash_kexec directly. */ if (!_crash_kexec_post_notifiers) { - printk_nmi_flush_on_panic(); + printk_safe_flush_on_panic(); __crash_kexec(NULL); /* @@ -213,7 +213,7 @@ void panic(const char *fmt, ...) atomic_notifier_call_chain(&panic_notifier_list, 0, buf); /* Call flush even twice. It tries harder with a single online CPU */ - printk_nmi_flush_on_panic(); + printk_safe_flush_on_panic(); kmsg_dump(KMSG_DUMP_PANIC); /* diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile index abb0042a427b..607928119f26 100644 --- a/kernel/printk/Makefile +++ b/kernel/printk/Makefile @@ -1,3 +1,3 @@ obj-y = printk.o -obj-$(CONFIG_PRINTK_NMI) += nmi.o +obj-$(CONFIG_PRINTK_NMI) += printk_safe.o obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o diff --git a/kernel/printk/nmi.c b/kernel/printk/printk_safe.c index f011aaef583c..fc80359dcd78 100644 --- a/kernel/printk/nmi.c +++ b/kernel/printk/printk_safe.c @@ -1,5 +1,5 @@ /* - * nmi.c - Safe printk in NMI context + * printk_safe.c - Safe printk in NMI context * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -39,18 +39,18 @@ * were handled or when IRQs are blocked. */ DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default; -static int printk_nmi_irq_ready; +static int printk_safe_irq_ready; atomic_t nmi_message_lost; -#define NMI_LOG_BUF_LEN ((1 << CONFIG_NMI_LOG_BUF_SHIFT) - \ +#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \ sizeof(atomic_t) - sizeof(struct irq_work)) -struct nmi_seq_buf { +struct printk_safe_seq_buf { atomic_t len; /* length of written data */ struct irq_work work; /* IRQ work that flushes the buffer */ - unsigned char buffer[NMI_LOG_BUF_LEN]; + unsigned char buffer[SAFE_LOG_BUF_LEN]; }; -static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq); +static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq); /* * Safe printk() for NMI context. It uses a per-CPU buffer to @@ -60,7 +60,7 @@ static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq); */ static int vprintk_nmi(const char *fmt, va_list args) { - struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq); + struct printk_safe_seq_buf *s = this_cpu_ptr(&nmi_print_seq); int add = 0; size_t len; @@ -91,7 +91,7 @@ again: goto again; /* Get flushed in a more safe context. */ - if (add && printk_nmi_irq_ready) { + if (add && printk_safe_irq_ready) { /* Make sure that IRQ work is really initialized. */ smp_rmb(); irq_work_queue(&s->work); @@ -100,7 +100,7 @@ again: return add; } -static void printk_nmi_flush_line(const char *text, int len) +static void printk_safe_flush_line(const char *text, int len) { /* * The buffers are flushed in NMI only on panic. The messages must @@ -111,11 +111,10 @@ static void printk_nmi_flush_line(const char *text, int len) printk_deferred("%.*s", len, text); else printk("%.*s", len, text); - } /* printk part of the temporary buffer line by line */ -static int printk_nmi_flush_buffer(const char *start, size_t len) +static int printk_safe_flush_buffer(const char *start, size_t len) { const char *c, *end; bool header; @@ -127,7 +126,7 @@ static int printk_nmi_flush_buffer(const char *start, size_t len) /* Print line by line. */ while (c < end) { if (*c == '\n') { - printk_nmi_flush_line(start, c - start + 1); + printk_safe_flush_line(start, c - start + 1); start = ++c; header = true; continue; @@ -140,7 +139,7 @@ static int printk_nmi_flush_buffer(const char *start, size_t len) continue; } - printk_nmi_flush_line(start, c - start); + printk_safe_flush_line(start, c - start); start = c++; header = true; continue; @@ -154,8 +153,8 @@ static int printk_nmi_flush_buffer(const char *start, size_t len) if (start < end && !header) { static const char newline[] = KERN_CONT "\n"; - printk_nmi_flush_line(start, end - start); - printk_nmi_flush_line(newline, strlen(newline)); + printk_safe_flush_line(start, end - start); + printk_safe_flush_line(newline, strlen(newline)); } return len; @@ -165,11 +164,12 @@ static int printk_nmi_flush_buffer(const char *start, size_t len) * Flush data from the associated per_CPU buffer. The function * can be called either via IRQ work or independently. */ -static void __printk_nmi_flush(struct irq_work *work) +static void __printk_safe_flush(struct irq_work *work) { static raw_spinlock_t read_lock = __RAW_SPIN_LOCK_INITIALIZER(read_lock); - struct nmi_seq_buf *s = container_of(work, struct nmi_seq_buf, work); + struct printk_safe_seq_buf *s = + container_of(work, struct printk_safe_seq_buf, work); unsigned long flags; size_t len; int i; @@ -194,9 +194,9 @@ more: * buffer size. */ if ((i && i >= len) || len > sizeof(s->buffer)) { - const char *msg = "printk_nmi_flush: internal error\n"; + const char *msg = "printk_safe_flush: internal error\n"; - printk_nmi_flush_line(msg, strlen(msg)); + printk_safe_flush_line(msg, strlen(msg)); len = 0; } @@ -205,7 +205,7 @@ more: /* Make sure that data has been written up to the @len */ smp_rmb(); - i += printk_nmi_flush_buffer(s->buffer + i, len - i); + i += printk_safe_flush_buffer(s->buffer + i, len - i); /* * Check that nothing has got added in the meantime and truncate @@ -221,31 +221,31 @@ out: } /** - * printk_nmi_flush - flush all per-cpu nmi buffers. + * printk_safe_flush - flush all per-cpu nmi buffers. * * The buffers are flushed automatically via IRQ work. This function * is useful only when someone wants to be sure that all buffers have * been flushed at some point. */ -void printk_nmi_flush(void) +void printk_safe_flush(void) { int cpu; for_each_possible_cpu(cpu) - __printk_nmi_flush(&per_cpu(nmi_print_seq, cpu).work); + __printk_safe_flush(&per_cpu(nmi_print_seq, cpu).work); } /** - * printk_nmi_flush_on_panic - flush all per-cpu nmi buffers when the system + * printk_safe_flush_on_panic - flush all per-cpu nmi buffers when the system * goes down. * - * Similar to printk_nmi_flush() but it can be called even in NMI context when + * Similar to printk_safe_flush() but it can be called even in NMI context when * the system goes down. It does the best effort to get NMI messages into * the main ring buffer. * * Note that it could try harder when there is only one CPU online. */ -void printk_nmi_flush_on_panic(void) +void printk_safe_flush_on_panic(void) { /* * Make sure that we could access the main ring buffer. @@ -259,25 +259,25 @@ void printk_nmi_flush_on_panic(void) raw_spin_lock_init(&logbuf_lock); } - printk_nmi_flush(); + printk_safe_flush(); } -void __init printk_nmi_init(void) +void __init printk_safe_init(void) { int cpu; for_each_possible_cpu(cpu) { - struct nmi_seq_buf *s = &per_cpu(nmi_print_seq, cpu); + struct printk_safe_seq_buf *s = &per_cpu(nmi_print_seq, cpu); - init_irq_work(&s->work, __printk_nmi_flush); + init_irq_work(&s->work, __printk_safe_flush); } /* Make sure that IRQ works are initialized before enabling. */ smp_wmb(); - printk_nmi_irq_ready = 1; + printk_safe_irq_ready = 1; /* Flush pending messages that did not have scheduled IRQ works. */ - printk_nmi_flush(); + printk_safe_flush(); } void printk_nmi_enter(void) diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c index 75554754eadf..5f7999eacad5 100644 --- a/lib/nmi_backtrace.c +++ b/lib/nmi_backtrace.c @@ -77,7 +77,7 @@ void nmi_trigger_cpumask_backtrace(const cpumask_t *mask, * Force flush any remote buffers that might be stuck in IRQ context * and therefore could not run their irq_work. */ - printk_nmi_flush(); + printk_safe_flush(); clear_bit_unlock(0, &backtrace_flag); put_cpu(); |