diff options
Diffstat (limited to 'kernel/printk/printk_safe.c')
| -rw-r--r-- | kernel/printk/printk_safe.c | 58 |
1 files changed, 37 insertions, 21 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index d7d091309054..a0a74c533e4b 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -308,24 +308,33 @@ static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args) void printk_nmi_enter(void) { - /* - * The size of the extra per-CPU buffer is limited. Use it only when - * the main one is locked. If this CPU is not in the safe context, - * the lock must be taken on another CPU and we could wait for it. - */ - if ((this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK) && - raw_spin_is_locked(&logbuf_lock)) { - this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK); - } else { - this_cpu_or(printk_context, PRINTK_NMI_DEFERRED_CONTEXT_MASK); - } + this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK); } void printk_nmi_exit(void) { - this_cpu_and(printk_context, - ~(PRINTK_NMI_CONTEXT_MASK | - PRINTK_NMI_DEFERRED_CONTEXT_MASK)); + this_cpu_and(printk_context, ~PRINTK_NMI_CONTEXT_MASK); +} + +/* + * Marks a code that might produce many messages in NMI context + * and the risk of losing them is more critical than eventual + * reordering. + * + * It has effect only when called in NMI context. Then printk() + * will try to store the messages into the main logbuf directly + * and use the per-CPU buffers only as a fallback when the lock + * is not available. + */ +void printk_nmi_direct_enter(void) +{ + if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK) + this_cpu_or(printk_context, PRINTK_NMI_DIRECT_CONTEXT_MASK); +} + +void printk_nmi_direct_exit(void) +{ + this_cpu_and(printk_context, ~PRINTK_NMI_DIRECT_CONTEXT_MASK); } #else @@ -363,6 +372,20 @@ void __printk_safe_exit(void) __printf(1, 0) int vprintk_func(const char *fmt, va_list args) { + /* + * Try to use the main logbuf even in NMI. But avoid calling console + * drivers that might have their own locks. + */ + if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK) && + raw_spin_trylock(&logbuf_lock)) { + int len; + + len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args); + raw_spin_unlock(&logbuf_lock); + defer_console_output(); + return len; + } + /* Use extra buffer in NMI when logbuf_lock is taken or in safe mode. */ if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK) return vprintk_nmi(fmt, args); @@ -371,13 +394,6 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args) if (this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK) return vprintk_safe(fmt, args); - /* - * Use the main logbuf when logbuf_lock is available in NMI. - * But avoid calling console drivers that might have their own locks. - */ - if (this_cpu_read(printk_context) & PRINTK_NMI_DEFERRED_CONTEXT_MASK) - return vprintk_deferred(fmt, args); - /* No obstacles. */ return vprintk_default(fmt, args); } |