Commit d37d39ae authored by Jason Wessel's avatar Jason Wessel
Browse files

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: default avatarJason Wessel <jason.wessel@windriver.com>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent efe2f29e
......@@ -78,6 +78,9 @@ typedef enum {
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 *, ...)
......
......@@ -23,6 +23,7 @@ static void kdb_show_stack(struct task_struct *p, void *addr)
{
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 @@ static void kdb_show_stack(struct task_struct *p, void *addr)
show_stack(p, NULL);
}
console_loglevel = old_lvl;
kdb_trap_printk--;
}
/*
......
......@@ -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 @@ static int kdb_search_string(char *searched, char *searchfor)
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 @@ int kdb_printf(const char *fmt, ...)
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 @@ int kdb_printf(const char *fmt, ...)
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 @@ int kdb_printf(const char *fmt, ...)
} 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;
}
......@@ -1056,7 +1056,9 @@ static void kdb_dumpregs(struct pt_regs *regs)
{
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 @@ static int kdb_sr(int argc, const char **argv)
if (argc != 1)
return KDB_ARGCOUNT;
sysrq_toggle_support(1);
kdb_trap_printk++;
handle_sysrq(*argv[1], NULL);
kdb_trap_printk--;
return 0;
}
......
......@@ -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 @@ asmlinkage int printk(const char *fmt, ...)
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);
......
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