kdb: Revive dmesg command
The kgdb dmesg command is broken after the printk rework. The old logic
in kdb code makes no sense in terms of current printk/logging storage
format, and KDB simply hangs forever.
This patch revives the command by switching to kmsg_dumper iterator.
The code is now much more simpler and shorter.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 67b847d..df17c93 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -14,6 +14,7 @@
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/kernel.h>
+#include <linux/kmsg_dump.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/sysrq.h>
@@ -2040,8 +2041,15 @@
*/
static int kdb_dmesg(int argc, const char **argv)
{
- char *syslog_data[4], *start, *end, c = '\0', *p;
- int diag, logging, logsize, lines = 0, adjust = 0, n;
+ int diag;
+ int logging;
+ int lines = 0;
+ int adjust = 0;
+ int n = 0;
+ int skip = 0;
+ struct kmsg_dumper dumper = { .active = 1 };
+ size_t len;
+ char buf[201];
if (argc > 2)
return KDB_ARGCOUNT;
@@ -2064,22 +2072,10 @@
kdb_set(2, setargs);
}
- /* syslog_data[0,1] physical start, end+1. syslog_data[2,3]
- * logical start, end+1. */
- kdb_syslog_data(syslog_data);
- if (syslog_data[2] == syslog_data[3])
- return 0;
- logsize = syslog_data[1] - syslog_data[0];
- start = syslog_data[2];
- end = syslog_data[3];
-#define KDB_WRAP(p) (((p - syslog_data[0]) % logsize) + syslog_data[0])
- for (n = 0, p = start; p < end; ++p) {
- c = *KDB_WRAP(p);
- if (c == '\n')
- ++n;
- }
- if (c != '\n')
- ++n;
+ kmsg_dump_rewind(&dumper);
+ while (kmsg_dump_get_line(&dumper, 1, NULL, 0, NULL))
+ n++;
+
if (lines < 0) {
if (adjust >= n)
kdb_printf("buffer only contains %d lines, nothing "
@@ -2087,21 +2083,11 @@
else if (adjust - lines >= n)
kdb_printf("buffer only contains %d lines, last %d "
"lines printed\n", n, n - adjust);
- if (adjust) {
- for (; start < end && adjust; ++start) {
- if (*KDB_WRAP(start) == '\n')
- --adjust;
- }
- if (start < end)
- ++start;
- }
- for (p = start; p < end && lines; ++p) {
- if (*KDB_WRAP(p) == '\n')
- ++lines;
- }
- end = p;
+ skip = adjust;
+ lines = abs(lines);
} else if (lines > 0) {
- int skip = n - (adjust + lines);
+ skip = n - lines - adjust;
+ lines = abs(lines);
if (adjust >= n) {
kdb_printf("buffer only contains %d lines, "
"nothing printed\n", n);
@@ -2112,35 +2098,24 @@
kdb_printf("buffer only contains %d lines, first "
"%d lines printed\n", n, lines);
}
- for (; start < end && skip; ++start) {
- if (*KDB_WRAP(start) == '\n')
- --skip;
- }
- for (p = start; p < end && lines; ++p) {
- if (*KDB_WRAP(p) == '\n')
- --lines;
- }
- end = p;
+ } else {
+ lines = n;
}
- /* Do a line at a time (max 200 chars) to reduce protocol overhead */
- c = '\n';
- while (start != end) {
- char buf[201];
- p = buf;
- if (KDB_FLAG(CMD_INTERRUPT))
- return 0;
- while (start < end && (c = *KDB_WRAP(start)) &&
- (p - buf) < sizeof(buf)-1) {
- ++start;
- *p++ = c;
- if (c == '\n')
- break;
+
+ if (skip >= n || skip < 0)
+ return 0;
+
+ kmsg_dump_rewind(&dumper);
+ while (kmsg_dump_get_line(&dumper, 1, buf, sizeof(buf), &len)) {
+ if (skip) {
+ skip--;
+ continue;
}
- *p = '\0';
- kdb_printf("%s", buf);
+ if (!lines--)
+ break;
+
+ kdb_printf("%.*s\n", (int)len - 1, buf);
}
- if (c != '\n')
- kdb_printf("\n");
return 0;
}
