diff options
Diffstat (limited to 'kernel/printk/printk.c')
| -rw-r--r-- | kernel/printk/printk.c | 86 |
1 files changed, 48 insertions, 38 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 9bf5404397e0..b77150ad1965 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -16,6 +16,8 @@ * 01Mar01 Andrew Morton */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include <linux/kernel.h> #include <linux/mm.h> #include <linux/tty.h> @@ -192,16 +194,7 @@ int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, return 0; } -/* - * Number of registered extended console drivers. - * - * If extended consoles are present, in-kernel cont reassembly is disabled - * and each fragment is stored as a separate log entry with proper - * continuation flag so that every emitted message has full metadata. This - * doesn't change the result for regular consoles or /proc/kmsg. For - * /dev/kmsg, as long as the reader concatenates messages according to - * consecutive continuation flags, the end result should be the same too. - */ +/* Number of registered extended console drivers. */ static int nr_ext_console_drivers; /* @@ -423,6 +416,7 @@ static u32 log_next_idx; /* the next printk record to write to the console */ static u64 console_seq; static u32 console_idx; +static u64 exclusive_console_stop_seq; /* the next printk record to read after the last 'clear' command */ static u64 clear_seq; @@ -437,6 +431,7 @@ static u32 clear_idx; /* record buffer */ #define LOG_ALIGN __alignof__(struct printk_log) #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) +#define LOG_BUF_LEN_MAX (u32)(1 << 31) static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); static char *log_buf = __log_buf; static u32 log_buf_len = __LOG_BUF_LEN; @@ -1037,18 +1032,28 @@ void log_buf_vmcoreinfo_setup(void) static unsigned long __initdata new_log_buf_len; /* we practice scaling the ring buffer by powers of 2 */ -static void __init log_buf_len_update(unsigned size) +static void __init log_buf_len_update(u64 size) { + if (size > (u64)LOG_BUF_LEN_MAX) { + size = (u64)LOG_BUF_LEN_MAX; + pr_err("log_buf over 2G is not supported.\n"); + } + if (size) size = roundup_pow_of_two(size); if (size > log_buf_len) - new_log_buf_len = size; + new_log_buf_len = (unsigned long)size; } /* save requested log_buf_len since it's too early to process it */ static int __init log_buf_len_setup(char *str) { - unsigned size = memparse(str, &str); + u64 size; + + if (!str) + return -EINVAL; + + size = memparse(str, &str); log_buf_len_update(size); @@ -1093,7 +1098,7 @@ void __init setup_log_buf(int early) { unsigned long flags; char *new_log_buf; - int free; + unsigned int free; if (log_buf != __log_buf) return; @@ -1113,7 +1118,7 @@ void __init setup_log_buf(int early) } if (unlikely(!new_log_buf)) { - pr_err("log_buf_len: %ld bytes not available\n", + pr_err("log_buf_len: %lu bytes not available\n", new_log_buf_len); return; } @@ -1126,8 +1131,8 @@ void __init setup_log_buf(int early) memcpy(log_buf, __log_buf, __LOG_BUF_LEN); logbuf_unlock_irqrestore(flags); - pr_info("log_buf_len: %d bytes\n", log_buf_len); - pr_info("early log buf free: %d(%d%%)\n", + pr_info("log_buf_len: %u bytes\n", log_buf_len); + pr_info("early log buf free: %u(%u%%)\n", free, (free * 100) / __LOG_BUF_LEN); } @@ -1767,12 +1772,8 @@ static void cont_flush(void) static bool cont_add(int facility, int level, enum log_flags flags, const char *text, size_t len) { - /* - * If ext consoles are present, flush and skip in-kernel - * continuation. See nr_ext_console_drivers definition. Also, if - * the line gets too long, split it up in separate records. - */ - if (nr_ext_console_drivers || cont.len + len > sizeof(cont.buf)) { + /* If the line gets too long, split it up in separate records. */ + if (cont.len + len > sizeof(cont.buf)) { cont_flush(); return false; } @@ -1795,9 +1796,6 @@ static bool cont_add(int facility, int level, enum log_flags flags, const char * cont_flush(); } - if (cont.len > (sizeof(cont.buf) * 80) / 100) - cont_flush(); - return true; } @@ -1889,8 +1887,9 @@ asmlinkage int vprintk_emit(int facility, int level, const char *fmt, va_list args) { int printed_len; - bool in_sched = false; + bool in_sched = false, pending_output; unsigned long flags; + u64 curr_log_seq; if (level == LOGLEVEL_SCHED) { level = LOGLEVEL_DEFAULT; @@ -1902,11 +1901,13 @@ asmlinkage int vprintk_emit(int facility, int level, /* This stops the holder of console_sem just where we want him */ logbuf_lock_irqsave(flags); + curr_log_seq = log_next_seq; printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args); + pending_output = (curr_log_seq != log_next_seq); logbuf_unlock_irqrestore(flags); /* If called from the scheduler, we can not call up(). */ - if (!in_sched) { + if (!in_sched && pending_output) { /* * Disable preemption to avoid being preempted while holding * console_sem which would prevent anyone from printing to @@ -1923,7 +1924,8 @@ asmlinkage int vprintk_emit(int facility, int level, preempt_enable(); } - wake_up_klogd(); + if (pending_output) + wake_up_klogd(); return printed_len; } EXPORT_SYMBOL(vprintk_emit); @@ -2009,6 +2011,7 @@ static u64 syslog_seq; static u32 syslog_idx; static u64 console_seq; static u32 console_idx; +static u64 exclusive_console_stop_seq; static u64 log_first_seq; static u32 log_first_idx; static u64 log_next_seq; @@ -2351,8 +2354,9 @@ again: printk_safe_enter_irqsave(flags); raw_spin_lock(&logbuf_lock); if (console_seq < log_first_seq) { - len = sprintf(text, "** %u printk messages dropped **\n", - (unsigned)(log_first_seq - console_seq)); + len = sprintf(text, + "** %llu printk messages dropped **\n", + log_first_seq - console_seq); /* messages are gone, move to first one */ console_seq = log_first_seq; @@ -2376,6 +2380,12 @@ skip: goto skip; } + /* Output to all consoles once old messages replayed. */ + if (unlikely(exclusive_console && + console_seq >= exclusive_console_stop_seq)) { + exclusive_console = NULL; + } + len += msg_print_text(msg, console_msg_format & MSG_FORMAT_SYSLOG, text + len, @@ -2418,10 +2428,6 @@ skip: console_locked = 0; - /* Release the exclusive_console once it is used */ - if (unlikely(exclusive_console)) - exclusive_console = NULL; - raw_spin_unlock(&logbuf_lock); up_console_sem(); @@ -2688,8 +2694,7 @@ void register_console(struct console *newcon) } if (newcon->flags & CON_EXTENDED) - if (!nr_ext_console_drivers++) - pr_info("printk: continuation disabled due to ext consoles, expect more fragments in /dev/kmsg\n"); + nr_ext_console_drivers++; if (newcon->flags & CON_PRINTBUFFER) { /* @@ -2699,13 +2704,18 @@ void register_console(struct console *newcon) logbuf_lock_irqsave(flags); console_seq = syslog_seq; console_idx = syslog_idx; - logbuf_unlock_irqrestore(flags); /* * We're about to replay the log buffer. Only do this to the * just-registered console to avoid excessive message spam to * the already-registered consoles. + * + * Set exclusive_console with disabled interrupts to reduce + * race window with eventual console_flush_on_panic() that + * ignores console_lock. */ exclusive_console = newcon; + exclusive_console_stop_seq = console_seq; + logbuf_unlock_irqrestore(flags); } console_unlock(); console_sysfs_notify(); |