[Crash-utility] [PATCH] Fix for the "log -a" option

[qiwuchen55 at gmail.com]

From: chenqiwu <chenqiwu at xiaomi.com>

Fix for the "log -a" option. The printk logbuf is a ring buffer,
if log_first_idx is larger than log_next_idx, there are two buffer
zones must be handled for logdump:
1) [log_first_idx, log_buf_len]
2) [0, log_next_idx]

However, the original code ignores the logdump for the second buffer
zone if log_first_idx is larger than log_next_idx. Without this patch,
the option fails with the following error message "duplicate log_buf
message pointer".

Signed-off-by: chenqiwu <chenqiwu at xiaomi.com>
---
 kernel.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel.c b/kernel.c
index 68ee282..7604fac 100644
--- a/kernel.c
+++ b/kernel.c
@@ -5278,8 +5278,12 @@ dump_variable_length_record_log(int msg_flags)
 		idx = log_next(idx, logbuf);
 
 		if (idx >= log_buf_len) {
-			error(INFO, "\ninvalid log_buf entry encountered\n");
-			break;
+			if (log_first_idx > log_next_idx)
+				idx = 0;
+			else {
+				error(INFO, "\ninvalid log_buf entry encountered\n");
+				break;
+			}
 		}
 
 		if (CRASHDEBUG(1) && (idx == log_next_idx))
-- 
1.9.1