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>

1 files changed, 20 insertions, 4 deletions

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index 58be7e9c9e95..c9b7f4f90bba 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 @@ 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;
+}
+