printk: introduce struct printk_buffers

Introduce a new struct printk_buffers to contain all the buffers
needed to read and format a printk message for output. Putting the
buffers inside a struct reduces the number of buffer pointers that
need to be tracked. Also, it allows usage of the sizeof() macro for
the buffer sizes, rather than expecting certain sized buffers being
passed in.

Note that since the output buffer for normal consoles is now
CONSOLE_EXT_LOG_MAX instead of CONSOLE_LOG_MAX, multi-line
messages that may have been previously truncated will now be
printed in full. This should be considered a feature and not a bug
since the CONSOLE_LOG_MAX restriction was about limiting static
buffer usage rather than limiting printed text.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20230109100800.1085541-5-john.ogness@linutronix.de

1 files changed, 10 insertions, 0 deletions

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index f394332410c9..6080d289a342 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -82,3 +82,13 @@ u16 printk_parse_prefix(const char *text, int *level,
 
 static inline bool printk_percpu_data_ready(void) { return false; }
 #endif /* CONFIG_PRINTK */
+
+/**
+ * struct printk_buffers - Buffers to read/format/output printk messages.
+ * @outbuf:	After formatting, contains text to output.
+ * @scratchbuf:	Used as temporary ringbuffer reading and string-print space.
+ */
+struct printk_buffers {
+	char	outbuf[CONSOLE_EXT_LOG_MAX];
+	char	scratchbuf[LOG_LINE_MAX];
+};