diff options
| -rw-r--r-- | kernel/printk/printk.c | 42 |
1 files changed, 39 insertions, 3 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 9f088ed..7131dd4 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -351,6 +351,32 @@ static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) return size; } +/* + * Define how much of the log buffer we could take at maximum. The value + * must be greater than two. Note that only half of the buffer is available + * when the index points to the middle. + */ +#define MAX_LOG_TAKE_PART 4 +static const char trunc_msg[] = "<truncated>"; + +static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, + u16 *dict_len, u32 *pad_len) +{ + /* + * The message should not take the whole buffer. Otherwise, it might + * get removed too soon. + */ + u32 max_text_len = log_buf_len / MAX_LOG_TAKE_PART; + if (*text_len > max_text_len) + *text_len = max_text_len; + /* enable the warning message */ + *trunc_msg_len = strlen(trunc_msg); + /* disable the "dict" completely */ + *dict_len = 0; + /* compute the size again, count also the warning message */ + return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); +} + /* insert record into the buffer, discard old ones, update heads */ static void log_store(int facility, int level, enum log_flags flags, u64 ts_nsec, @@ -359,13 +385,19 @@ static void log_store(int facility, int level, { struct printk_log *msg; u32 size, pad_len; + u16 trunc_msg_len = 0; /* number of '\0' padding bytes to next message */ size = msg_used_size(text_len, dict_len, &pad_len); - /* if message does not fit empty log buffer, ignore it */ - if (log_make_free_space(size)) - return; + if (log_make_free_space(size)) { + /* truncate the message if it is too long for empty buffer */ + size = truncate_msg(&text_len, &trunc_msg_len, + &dict_len, &pad_len); + /* survive when the log buffer is too small for trunc_msg */ + if (log_make_free_space(size)) + return; + } if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { /* @@ -381,6 +413,10 @@ static void log_store(int facility, int level, msg = (struct printk_log *)(log_buf + log_next_idx); memcpy(log_text(msg), text, text_len); msg->text_len = text_len; + if (trunc_msg_len) { + memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); + msg->text_len += trunc_msg_len; + } memcpy(log_dict(msg), dict, dict_len); msg->dict_len = dict_len; msg->facility = facility; |