diff options
Diffstat (limited to 'kernel/printk/printk_safe.c')
| -rw-r--r-- | kernel/printk/printk_safe.c | 30 |
1 files changed, 11 insertions, 19 deletions
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index 2e9e3ed7d63e..7a1414622051 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -16,7 +16,7 @@ #include "internal.h" /* - * printk() could not take logbuf_lock in NMI context. Instead, + * In NMI and safe mode, printk() avoids taking locks. Instead, * it uses an alternative implementation that temporary stores * the strings into a per-CPU buffer. The content of the buffer * is later flushed into the main ring buffer via IRQ work. @@ -267,17 +267,9 @@ void printk_safe_flush(void) void printk_safe_flush_on_panic(void) { /* - * Make sure that we could access the main ring buffer. + * Make sure that we could access the safe buffers. * Do not risk a double release when more CPUs are up. */ - if (raw_spin_is_locked(&logbuf_lock)) { - if (num_online_cpus() > 1) - return; - - debug_locks_off(); - raw_spin_lock_init(&logbuf_lock); - } - if (raw_spin_is_locked(&safe_read_lock)) { if (num_online_cpus() > 1) return; @@ -319,9 +311,7 @@ void noinstr printk_nmi_exit(void) * 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. + * will store the messages into the main logbuf directly. */ void printk_nmi_direct_enter(void) { @@ -367,7 +357,7 @@ void __printk_safe_exit(void) this_cpu_dec(printk_context); } -__printf(1, 0) int vprintk_func(const char *fmt, va_list args) +asmlinkage int vprintk(const char *fmt, va_list args) { #ifdef CONFIG_KGDB_KDB /* Allow to pass printk() to kdb but avoid a recursion. */ @@ -376,20 +366,21 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args) #endif /* - * Try to use the main logbuf even in NMI. But avoid calling console + * 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)) { + if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK)) { + unsigned long flags; int len; + printk_safe_enter_irqsave(flags); len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args); - raw_spin_unlock(&logbuf_lock); + printk_safe_exit_irqrestore(flags); defer_console_output(); return len; } - /* Use extra buffer in NMI when logbuf_lock is taken or in safe mode. */ + /* Use extra buffer in NMI. */ if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK) return vprintk_nmi(fmt, args); @@ -420,3 +411,4 @@ void __init printk_safe_init(void) /* Flush pending messages that did not have scheduled IRQ works. */ printk_safe_flush(); } +EXPORT_SYMBOL(vprintk); |