printk: fix kmsg_dump_get_buffer length calulations

[ Upstream commit 89ccf18f032f26946e2ea6258120472eec6aa745 ]

kmsg_dump_get_buffer() uses @syslog to determine if the syslog
prefix should be written to the buffer. However, when calculating
the maximum number of records that can fit into the buffer, it
always counts the bytes from the syslog prefix.

Use @syslog when calculating the maximum number of records that can
fit into the buffer.

Fixes: e2ae715d66bf ("kmsg - kmsg_dump() use iterator to receive log buffer content")
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20210113164413.1599-1-john.ogness@linutronix.de
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index bc1e3b5..801f8bc 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3376,7 +3376,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
        while (prb_read_valid_info(prb, seq, &info, &line_count)) {
                if (r.info->seq >= dumper->next_seq)
                        break;
-               l += get_record_print_text_size(&info, line_count, true, time);
+               l += get_record_print_text_size(&info, line_count, syslog, time);
                seq = r.info->seq + 1;
        }
 
@@ -3386,7 +3386,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
                                                &info, &line_count)) {
                if (r.info->seq >= dumper->next_seq)
                        break;
-               l -= get_record_print_text_size(&info, line_count, true, time);
+               l -= get_record_print_text_size(&info, line_count, syslog, time);
                seq = r.info->seq + 1;
        }