From bc792e612e78a24ae0b30cc5b85f2368379ba4d4 Mon Sep 17 00:00:00 2001 From: Anton Vorontsov Date: Fri, 20 Jul 2012 17:27:37 -0700 Subject: 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 Signed-off-by: Linus Torvalds --- kernel/debug/kdb/kdb_main.c | 91 ++++++++++++++++----------------------------- 1 file changed, 33 insertions(+), 58 deletions(-) (limited to 'kernel/debug/kdb/kdb_main.c') diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 67b847dfa2bb..df17c935d3c6 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -2040,8 +2041,15 @@ static int kdb_env(int argc, const char **argv) */ 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 @@ static int kdb_dmesg(int argc, const char **argv) 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 @@ static int kdb_dmesg(int argc, const char **argv) 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 @@ static int kdb_dmesg(int argc, const char **argv) 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; } -- cgit v1.2.3 From c064da47144b11be4697a4611f640086a663016a Mon Sep 17 00:00:00 2001 From: Anton Vorontsov Date: Fri, 20 Jul 2012 17:28:25 -0700 Subject: kdb: Switch to nolock variants of kmsg_dump functions The locked variants are prone to deadlocks (suppose we got to the debugger w/ the logbuf lock held), so let's switch to nolock variants. Signed-off-by: Anton Vorontsov Signed-off-by: Linus Torvalds --- kernel/debug/kdb/kdb_main.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/debug/kdb/kdb_main.c') diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index df17c935d3c6..1f91413edb87 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -2072,8 +2072,8 @@ static int kdb_dmesg(int argc, const char **argv) kdb_set(2, setargs); } - kmsg_dump_rewind(&dumper); - while (kmsg_dump_get_line(&dumper, 1, NULL, 0, NULL)) + kmsg_dump_rewind_nolock(&dumper); + while (kmsg_dump_get_line_nolock(&dumper, 1, NULL, 0, NULL)) n++; if (lines < 0) { @@ -2105,8 +2105,8 @@ static int kdb_dmesg(int argc, const char **argv) if (skip >= n || skip < 0) return 0; - kmsg_dump_rewind(&dumper); - while (kmsg_dump_get_line(&dumper, 1, buf, sizeof(buf), &len)) { + kmsg_dump_rewind_nolock(&dumper); + while (kmsg_dump_get_line_nolock(&dumper, 1, buf, sizeof(buf), &len)) { if (skip) { skip--; continue; -- cgit v1.2.3 From 0f26d0e0a715556270d85b7946b99546a2f92888 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Mon, 30 Jul 2012 22:44:41 -0500 Subject: kdb: Remove unused KDB_FLAG_ONLY_DO_DUMP This code cleanup was missed in the original kdb merge, and this code is simply not used at all. The code that was previously used to set the KDB_FLAG_ONLY_DO_DUMP was removed prior to the initial kdb merge. Signed-off-by: Jason Wessel --- include/linux/kdb.h | 2 -- kernel/debug/kdb/kdb_main.c | 15 +-------------- 2 files changed, 1 insertion(+), 16 deletions(-) (limited to 'kernel/debug/kdb/kdb_main.c') diff --git a/include/linux/kdb.h b/include/linux/kdb.h index 064725854db8..42d9e863a313 100644 --- a/include/linux/kdb.h +++ b/include/linux/kdb.h @@ -75,8 +75,6 @@ extern const char *kdb_diemsg; #define KDB_FLAG_CATASTROPHIC (1 << 1) /* A catastrophic event has occurred */ #define KDB_FLAG_CMD_INTERRUPT (1 << 2) /* Previous command was interrupted */ #define KDB_FLAG_NOIPI (1 << 3) /* Do not send IPIs */ -#define KDB_FLAG_ONLY_DO_DUMP (1 << 4) /* Only do a dump, used when - * kdb is off */ #define KDB_FLAG_NO_CONSOLE (1 << 5) /* No console is available, * kdb is disabled */ #define KDB_FLAG_NO_VT_CONSOLE (1 << 6) /* No VT console is available, do diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 1f91413edb87..31df1706b9a9 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -139,11 +139,10 @@ static const int __nkdb_err = sizeof(kdbmsgs) / sizeof(kdbmsg_t); static char *__env[] = { #if defined(CONFIG_SMP) "PROMPT=[%d]kdb> ", - "MOREPROMPT=[%d]more> ", #else "PROMPT=kdb> ", - "MOREPROMPT=more> ", #endif + "MOREPROMPT=more> ", "RADIX=16", "MDCOUNT=8", /* lines of md output */ KDB_PLATFORM_ENV, @@ -1236,18 +1235,6 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs, *cmdbuf = '\0'; *(cmd_hist[cmd_head]) = '\0'; - if (KDB_FLAG(ONLY_DO_DUMP)) { - /* kdb is off but a catastrophic error requires a dump. - * Take the dump and reboot. - * Turn on logging so the kdb output appears in the log - * buffer in the dump. - */ - const char *setargs[] = { "set", "LOGGING", "1" }; - kdb_set(2, setargs); - kdb_reboot(0, NULL); - /*NOTREACHED*/ - } - do_full_getstr: #if defined(CONFIG_SMP) snprintf(kdb_prompt_str, CMD_BUFLEN, kdbgetenv("PROMPT"), -- cgit v1.2.3