The patch titled
Subject: printk: add clear_idx symbol to vmcoreinfo
has been added to the -mm tree. Its filename is
printk-add-clear_idx-symbol-to-vmcoreinfo.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/printk-add-clear_idx-symbol-to-vmcoreinfo.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/printk-add-clear_idx-symbol-to-vmcoreinfo.patch
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------------------------------------------------------
From: Ivan Delalande <colona@xxxxxxxxxx>
Subject: printk: add clear_idx symbol to vmcoreinfo
This allows us to extract from the vmcore only the messages emitted since
the last time the ring buffer was cleared. We just have to make sure its
value is always up-to-date, when old messages are discarded to free space
in log_make_free_space() for example.
Signed-off-by: Zeyu Zhao <zzy8200@xxxxxxxxx>
Signed-off-by: Ivan Delalande <colona@xxxxxxxxxx>
Cc: Kay Sievers <kay@xxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk/printk.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff -puN kernel/printk/printk.c~printk-add-clear_idx-symbol-to-vmcoreinfo kernel/printk/printk.c
--- a/kernel/printk/printk.c~printk-add-clear_idx-symbol-to-vmcoreinfo
+++ a/kernel/printk/printk.c
@@ -368,16 +368,20 @@ static int logbuf_has_space(u32 msg_size
static int log_make_free_space(u32 msg_size)
{
- while (log_first_seq < log_next_seq) {
- if (logbuf_has_space(msg_size, false))
- return 0;
+ while (log_first_seq < log_next_seq &&
+ !logbuf_has_space(msg_size, false)) {
/* drop old messages until we have enough contiguous space */
log_first_idx = log_next(log_first_idx);
log_first_seq++;
}
+ if (clear_seq < log_first_seq) {
+ clear_seq = log_first_seq;
+ clear_idx = log_first_idx;
+ }
+
/* sequence numbers are equal, so the log buffer is empty */
- if (logbuf_has_space(msg_size, true))
+ if (logbuf_has_space(msg_size, log_first_seq == log_next_seq))
return 0;
return -ENOMEM;
@@ -855,6 +859,7 @@ void log_buf_kexec_setup(void)
VMCOREINFO_SYMBOL(log_buf);
VMCOREINFO_SYMBOL(log_buf_len);
VMCOREINFO_SYMBOL(log_first_idx);
+ VMCOREINFO_SYMBOL(clear_idx);
VMCOREINFO_SYMBOL(log_next_idx);
/*
* Export struct printk_log size and field offsets. User space tools can
@@ -1217,12 +1222,6 @@ static int syslog_print_all(char __user
u32 idx;
enum log_flags prev;
- if (clear_seq < log_first_seq) {
- /* messages are gone, move to first available one */
- clear_seq = log_first_seq;
- clear_idx = log_first_idx;
- }
-
/*
* Find first record that fits, including all following records,
* into the user-provided buffer for this dump.
_
Patches currently in -mm which might be from colona@xxxxxxxxxx are
printk-add-clear_idx-symbol-to-vmcoreinfo.patch
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