printk: fix kmsg_dump_get_buffer length calulations

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

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index c8847ee571f0e1f22b022ceb99835e5813ac2702..96e24074c96267dfbd1f0bbaf23758b4d7d3619a 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3423,7 +3423,7 @@ 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;
        }
 
@@ -3433,7 +3433,7 @@ 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;
        }