printk: finalize records with trailing newlines

Any record with a trailing newline (LOG_NEWLINE flag) cannot
be continued because the newline has been stripped and will
not be visible if the message is appended. This was already
handled correctly when committing in log_output() but was
not handled correctly when committing in log_store().

Fixes: f5f022e5 ("printk: reimplement log_cont using record extension")
Link: https://lore.kernel.org/r/20201126114836.14750-1-john.ogness@linutronix.deReported-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

kernel/printk/printk.c

@@ -528,8 +528,8 @@ static int log_store(u32 caller_id, int facility, int level,
 	if (dev_info)
 		memcpy(&r.info->dev_info, dev_info, sizeof(r.info->dev_info));
 
-	/* insert message */
-	if ((flags & LOG_CONT) || !(flags & LOG_NEWLINE))
+	/* A message without a trailing newline can be continued. */
+	if (!(flags & LOG_NEWLINE))
 		prb_commit(&e);
 	else
 		prb_final_commit(&e);