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authorKay Sievers <kay@vrfy.org>2012-07-16 18:35:30 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-16 18:35:30 -0700
commitd39f3d77c9b1fe7cc33a14beb4a4849af0a4ac22 (patch)
treebf3a4fd34aa850a5f30f966dfd98a40a424f6b9a /kernel/printk.c
parent96efedf1491cdf0616e5e4fff0711cebf20f69c7 (diff)
downloadlinux-d39f3d77c9b1fe7cc33a14beb4a4849af0a4ac22.tar.gz
kmsg - export "continuation record" flag to /dev/kmsg
In some cases we are forced to store individual records for a continuation line print. Export a flag to allow the external re-construction of the line. The flag allows us to apply a similar logic externally which is used internally when the console, /proc/kmsg or the syslog() output is printed. $ cat /dev/kmsg 4,165,0,-;Free swap = 0kB 4,166,0,-;Total swap = 0kB 6,167,0,c;[ 4,168,0,+;0 4,169,0,+;1 4,170,0,+;2 4,171,0,+;3 4,172,0,+;] 6,173,0,-;[0 1 2 3 ] 6,174,0,-;Console: colour VGA+ 80x25 6,175,0,-;console [tty0] enabled Signed-off-by: Kay Sievers <kay@vrfy.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel/printk.c')
-rw-r--r--kernel/printk.c23
1 files changed, 21 insertions, 2 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index 6c3d5bf14da..a41106e1907 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -361,6 +361,7 @@ static void log_store(int facility, int level,
struct devkmsg_user {
u64 seq;
u32 idx;
+ enum log_flags prev;
struct mutex lock;
char buf[8192];
};
@@ -426,6 +427,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
struct log *msg;
u64 ts_usec;
size_t i;
+ char cont = '-';
size_t len;
ssize_t ret;
@@ -463,8 +465,25 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
msg = log_from_idx(user->idx);
ts_usec = msg->ts_nsec;
do_div(ts_usec, 1000);
- len = sprintf(user->buf, "%u,%llu,%llu;",
- (msg->facility << 3) | msg->level, user->seq, ts_usec);
+
+ /*
+ * If we couldn't merge continuation line fragments during the print,
+ * export the stored flags to allow an optional external merge of the
+ * records. Merging the records isn't always neccessarily correct, like
+ * when we hit a race during printing. In most cases though, it produces
+ * better readable output. 'c' in the record flags mark the first
+ * fragment of a line, '+' the following.
+ */
+ if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
+ cont = 'c';
+ else if ((msg->flags & LOG_CONT) ||
+ ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
+ cont = '+';
+
+ len = sprintf(user->buf, "%u,%llu,%llu,%c;",
+ (msg->facility << 3) | msg->level,
+ user->seq, ts_usec, cont);
+ user->prev = msg->flags;
/* escape non-printable characters */
for (i = 0; i < msg->text_len; i++) {