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 (file)
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -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 *, ...)

diff --git a/kernel/debug/kdb/kdb_bt.c b/kernel/debug/kdb/kdb_bt.c
index 483fa4e..2f62fe8 100644 (file)
--- a/kernel/debug/kdb/kdb_bt.c
+++ b/kernel/debug/kdb/kdb_bt.c
@@ -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--;
 }
 
 /*

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 58be7e9..c9b7f4f 100644 (file)
--- 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 @@ 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;
+}
+

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 64ef9ac..b724c79 100644 (file)
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -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;
 }

diff --git a/kernel/printk.c b/kernel/printk.c
index 9213b8b..444b770 100644 (file)
--- 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 @@ 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);