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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

include/linux/kdb.h

+3 −0
Original line number Diff line number Diff line
@@ -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 *, ...)

kernel/debug/kdb/kdb_bt.c

+2 −0
Original line number Diff line number Diff line
@@ -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--;

}



/*

kernel/debug/kdb/kdb_io.c

+20 −4
Original line number Diff line number Diff line
@@ -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 @@ kdb_print_out: 
	} 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;

}

kernel/debug/kdb/kdb_main.c

+4 −0
Original line number Diff line number Diff line
@@ -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;

}

kernel/printk.c

+9 −0
Original line number Diff line number Diff line
@@ -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);