printk,kdb: capture printk() when in kdb shell
Certain calls from the kdb shell will call out to printk(), and any of
these calls should get vectored back to the kdb_printf() so that the
kdb pager and processing can be used, as well as to properly channel
I/O to the polled I/O devices.
CC: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/include/linux/kdb.h b/include/linux/kdb.h
index d72fa39..ccb2b3e 100644
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -78,6 +78,9 @@
KDB_REASON_SSTEP, /* Single Step trap. - regs valid */
} kdb_reason_t;
+extern int kdb_trap_printk;
+extern int vkdb_printf(const char *fmt, va_list args)
+ __attribute__ ((format (printf, 1, 0)));
extern int kdb_printf(const char *, ...)
__attribute__ ((format (printf, 1, 2)));
typedef int (*kdb_printf_t)(const char *, ...)
diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
index 483fa4e..2f62fe8 100644
--- a/kernel/debug/kdb/kdb_bt.c
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -23,6 +23,7 @@
{
int old_lvl = console_loglevel;
console_loglevel = 15;
+ kdb_trap_printk++;
kdb_set_current_task(p);
if (addr) {
show_stack((struct task_struct *)p, addr);
@@ -36,6 +37,7 @@
show_stack(p, NULL);
}
console_loglevel = old_lvl;
+ kdb_trap_printk--;
}
/*
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 58be7e9..c9b7f4f9 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -29,6 +29,7 @@
#define CMD_BUFLEN 256
char kdb_prompt_str[CMD_BUFLEN];
+int kdb_trap_printk;
static void kgdb_transition_check(char *buffer)
{
@@ -533,12 +534,12 @@
return 0;
}
-int kdb_printf(const char *fmt, ...)
+int vkdb_printf(const char *fmt, va_list ap)
{
- va_list ap;
int diag;
int linecount;
int logging, saved_loglevel = 0;
+ int saved_trap_printk;
int got_printf_lock = 0;
int retlen = 0;
int fnd, len;
@@ -549,6 +550,9 @@
unsigned long uninitialized_var(flags);
preempt_disable();
+ saved_trap_printk = kdb_trap_printk;
+ kdb_trap_printk = 0;
+
/* Serialize kdb_printf if multiple cpus try to write at once.
* But if any cpu goes recursive in kdb, just print the output,
* even if it is interleaved with any other text.
@@ -575,9 +579,7 @@
next_avail = kdb_buffer;
size_avail = sizeof(kdb_buffer);
}
- va_start(ap, fmt);
vsnprintf(next_avail, size_avail, fmt, ap);
- va_end(ap);
/*
* If kdb_parse() found that the command was cmd xxx | grep yyy
@@ -805,6 +807,20 @@
} else {
__release(kdb_printf_lock);
}
+ kdb_trap_printk = saved_trap_printk;
preempt_enable();
return retlen;
}
+
+int kdb_printf(const char *fmt, ...)
+{
+ va_list ap;
+ int r;
+
+ va_start(ap, fmt);
+ r = vkdb_printf(fmt, ap);
+ va_end(ap);
+
+ return r;
+}
+
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 64ef9ac..b724c79 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1056,7 +1056,9 @@
{
int old_lvl = console_loglevel;
console_loglevel = 15;
+ kdb_trap_printk++;
show_regs(regs);
+ kdb_trap_printk--;
kdb_printf("\n");
console_loglevel = old_lvl;
}
@@ -1819,7 +1821,9 @@
if (argc != 1)
return KDB_ARGCOUNT;
sysrq_toggle_support(1);
+ kdb_trap_printk++;
handle_sysrq(*argv[1], NULL);
+ kdb_trap_printk--;
return 0;
}
diff --git a/kernel/printk.c b/kernel/printk.c
index 9213b8b5..444b770 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -33,6 +33,7 @@
#include <linux/bootmem.h>
#include <linux/syscalls.h>
#include <linux/kexec.h>
+#include <linux/kdb.h>
#include <linux/ratelimit.h>
#include <linux/kmsg_dump.h>
#include <linux/syslog.h>
@@ -602,6 +603,14 @@
va_list args;
int r;
+#ifdef CONFIG_KGDB_KDB
+ if (unlikely(kdb_trap_printk)) {
+ va_start(args, fmt);
+ r = vkdb_printf(fmt, args);
+ va_end(args);
+ return r;
+ }
+#endif
va_start(args, fmt);
r = vprintk(fmt, args);
va_end(args);
