linux-kernel - [PATCH] printk: fix kmsg_dump_get

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Date:   Wed, 13 Jan 2021 17:50:13 +0106
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] 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@...utronix.de>
---
 kernel/printk/printk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ffdd0dc7ec6d..848b56efc9d7 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3427,7 +3427,7 @@ 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;
 	}
 
@@ -3437,7 +3437,7 @@ 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;
 	}
 
-- 
2.20.1