printk: make reading the kernel log flush pending lines
That will mean that any possible subsequent continuation will now be
broken up onto a line of its own (since reading the log has finalized
the beginning og the line), but if user space has activated system
logging (or if there's a kernel message dump going on) that is the right
thing to do.
And now that we actually get the continuation flags _right_ for this
all, the user space logger that is reading the kernel messages can
actually see the continuation marker. Not that anybody seems to really
bother with it (or care), but in theory user space can do its own
message stitching.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index f6fe60d..170d3a8 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -783,6 +783,8 @@
return ret;
}
+static void cont_flush(void);
+
static ssize_t devkmsg_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -798,6 +800,7 @@
if (ret)
return ret;
raw_spin_lock_irq(&logbuf_lock);
+ cont_flush();
while (user->seq == log_next_seq) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
@@ -860,6 +863,7 @@
return -ESPIPE;
raw_spin_lock_irq(&logbuf_lock);
+ cont_flush();
switch (whence) {
case SEEK_SET:
/* the first record */
@@ -898,6 +902,7 @@
poll_wait(file, &log_wait, wait);
raw_spin_lock_irq(&logbuf_lock);
+ cont_flush();
if (user->seq < log_next_seq) {
/* return error when data has vanished underneath us */
if (user->seq < log_first_seq)
@@ -1284,6 +1289,7 @@
size_t skip;
raw_spin_lock_irq(&logbuf_lock);
+ cont_flush();
if (syslog_seq < log_first_seq) {
/* messages are gone, move to first one */
syslog_seq = log_first_seq;
@@ -1343,6 +1349,7 @@
return -ENOMEM;
raw_spin_lock_irq(&logbuf_lock);
+ cont_flush();
if (buf) {
u64 next_seq;
u64 seq;
@@ -1504,6 +1511,7 @@
/* Number of chars in the log buffer */
case SYSLOG_ACTION_SIZE_UNREAD:
raw_spin_lock_irq(&logbuf_lock);
+ cont_flush();
if (syslog_seq < log_first_seq) {
/* messages are gone, move to first one */
syslog_seq = log_first_seq;
@@ -3016,6 +3024,7 @@
dumper->active = true;
raw_spin_lock_irqsave(&logbuf_lock, flags);
+ cont_flush();
dumper->cur_seq = clear_seq;
dumper->cur_idx = clear_idx;
dumper->next_seq = log_next_seq;
@@ -3106,6 +3115,7 @@
bool ret;
raw_spin_lock_irqsave(&logbuf_lock, flags);
+ cont_flush();
ret = kmsg_dump_get_line_nolock(dumper, syslog, line, size, len);
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
@@ -3148,6 +3158,7 @@
goto out;
raw_spin_lock_irqsave(&logbuf_lock, flags);
+ cont_flush();
if (dumper->cur_seq < log_first_seq) {
/* messages are gone, move to first available one */
dumper->cur_seq = log_first_seq;
