[Devel] [PATCH] C/R: simplify checkpoint debugging

[Nathan Lynch]

To enable printing of checkpoint/restart messages, one must enable
CHECKPOINT_DEBUG and boot with ckpt_debug= ... something I haven't
been able to figure out.  Further complicating matters is that if
DYNAMIC_DEBUG is enabled, you still won't get any debugging output
unless you manually enable debug output for all the functions you're
interested in via <debugfs>/dynamic_debug/control.  At this stage of
development most users will want all C/R messages either on or off and
don't need a fancy filtering mechanism.

Change ckpt_debug to print messages if CHECKPOINT_DEBUG=y.  Otherwise
it will emit nothing.  Remove ckpt_debug= setup code.  Reword
CHECKPOINT_DEBUG config help text appropriately.

Signed-off-by: Nathan Lynch <ntl at pobox.com>
---
 checkpoint/sys.c           |   22 ----------------------
 include/linux/checkpoint.h |    4 +---
 lib/Kconfig.debug          |    9 +++------
 3 files changed, 4 insertions(+), 31 deletions(-)

diff --git a/checkpoint/sys.c b/checkpoint/sys.c
index 38a5299..3c0056f 100644
--- a/checkpoint/sys.c
+++ b/checkpoint/sys.c
@@ -338,25 +338,3 @@ SYSCALL_DEFINE3(restart, pid_t, pid, int, fd, unsigned long, flags)
 	ckpt_ctx_put(ctx);
 	return ret;
 }
-
-
-/* 'ckpt_debug_level' controls the verbosity level of c/r code */
-#ifdef CONFIG_CHECKPOINT_DEBUG
-
-/* FIX: allow to change during runtime */
-unsigned long __read_mostly ckpt_debug_level = CKPT_DDEFAULT;
-
-static __init int ckpt_debug_setup(char *s)
-{
-	long val, ret;
-
-	ret = strict_strtoul(s, 10, &val);
-	if (ret < 0)
-		return ret;
-	ckpt_debug_level = val;
-	return 0;
-}
-
-__setup("ckpt_debug=", ckpt_debug_setup);
-
-#endif /* CONFIG_CHECKPOINT_DEBUG */
diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index b92bf95..f1aad34 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -264,13 +264,11 @@ extern int restore_memory_contents(struct ckpt_ctx *ctx, struct inode *inode);
 #endif
 
 #ifdef CONFIG_CHECKPOINT_DEBUG
-extern unsigned long ckpt_debug_level;
 
 /* use this to select a specific debug level */
 #define _ckpt_debug(level, fmt, args...)			\
 	do {						\
-		if (ckpt_debug_level & (level))		\
-			pr_debug("[%d:c/r:%s] " fmt,	\
+		printk(KERN_DEBUG "[%d:c/r:%s] " fmt,	\
 				task_pid_vnr(current),	\
 				 __func__, ## args);	\
 	} while (0)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ab795a6..2f6556b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -966,13 +966,10 @@ config CHECKPOINT_DEBUG
 	depends on CHECKPOINT
 	default y
 	help
-	  This options turns on the debugging output of checkpoint/restart.
-	  The level of verbosity is controlled by 'ckpt_debug_level' and can
-	  be set at boot time with "ckpt_debug=" option.
+	  If enabled, debugging messages related to checkpoint and
+	  restart operations will be printed to the kernel log.
 
-	  Turning this option off will reduce the size of the c/r code. If
-	  turned on, it is unlikely to incur visible overhead if the debug
-	  level is set to zero.
+	  Turn this on if you plan to test checkpoint/restart.
 
 source "samples/Kconfig"
 
-- 
1.6.0.6

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