dynamic_debug: describe_flags with '=[pmflt_]*'

Change describe_flags() to emit '=[pmflt_]+' for current callsite
flags, or just '=_' when they're disabled.  Having '=' in output
allows a more selective grep expression; in contrast '-' may appear
in filenames, line-ranges, and format-strings.  '=' also has better
mnemonics, saying; "the current setting is equal to <flags>".

This allows grep "=_" <dbgfs>/dynamic_debug/control to see disabled
callsites while avoiding the many occurrences of " = " seen in format
strings.

Enlarge flagsbufs to handle additional flag char, and alter
ddebug_parse_flags() to allow flags=0, so that user can turn off all
debug flags via:

  ~# echo =_ > <dbgfs>/dynamic_debug/control

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 29ea09a..fc39640 100644 (file)
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h
@@ -21,7 +21,8 @@ struct _ddebug {
         * The bits here are changed dynamically when the user
         * writes commands to <debugfs>/dynamic_debug/control
         */
-#define _DPRINTK_FLAGS_PRINT   (1<<0)  /* printk() a message using the format */
+#define _DPRINTK_FLAGS_NONE    0
+#define _DPRINTK_FLAGS_PRINT   (1<<0) /* printk() a message using the format */
 #define _DPRINTK_FLAGS_INCL_MODNAME    (1<<1)
 #define _DPRINTK_FLAGS_INCL_FUNCNAME   (1<<2)
 #define _DPRINTK_FLAGS_INCL_LINENO     (1<<3)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index b199e09..cde4dfe 100644 (file)
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -75,6 +75,7 @@ static struct { unsigned flag:8; char opt_char; } opt_array[] = {
        { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
        { _DPRINTK_FLAGS_INCL_LINENO, 'l' },
        { _DPRINTK_FLAGS_INCL_TID, 't' },
+       { _DPRINTK_FLAGS_NONE, '_' },
 };
 
 /* format a string into buf[] which describes the _ddebug's flags */
@@ -84,12 +85,12 @@ static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
        char *p = buf;
        int i;
 
-       BUG_ON(maxlen < 4);
+       BUG_ON(maxlen < 6);
        for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
                if (dp->flags & opt_array[i].flag)
                        *p++ = opt_array[i].opt_char;
        if (p == buf)
-               *p++ = '-';
+               *p++ = '_';
        *p = '\0';
 
        return buf;
@@ -108,7 +109,7 @@ static void ddebug_change(const struct ddebug_query *query,
        struct ddebug_table *dt;
        unsigned int newflags;
        unsigned int nfound = 0;
-       char flagbuf[8];
+       char flagbuf[10];
 
        /* search for matching ddebugs */
        mutex_lock(&ddebug_lock);
@@ -152,7 +153,7 @@ static void ddebug_change(const struct ddebug_query *query,
                                continue;
                        dp->flags = newflags;
                        if (verbose)
-                               pr_info("changed %s:%d [%s]%s %s\n",
+                               pr_info("changed %s:%d [%s]%s =%s\n",
                                        dp->filename, dp->lineno,
                                        dt->mod_name, dp->function,
                                        ddebug_describe_flags(dp, flagbuf,
@@ -370,8 +371,6 @@ static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
                if (i < 0)
                        return -EINVAL;
        }
-       if (flags == 0)
-               return -EINVAL;
        if (verbose)
                pr_info("flags=0x%x\n", flags);
 
@@ -666,7 +665,7 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
 {
        struct ddebug_iter *iter = m->private;
        struct _ddebug *dp = p;
-       char flagsbuf[8];
+       char flagsbuf[10];
 
        if (verbose)
                pr_info("called m=%p p=%p\n", m, p);
@@ -677,10 +676,10 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
                return 0;
        }
 
-       seq_printf(m, "%s:%u [%s]%s %s \"",
-                  dp->filename, dp->lineno,
-                  iter->table->mod_name, dp->function,
-                  ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
+       seq_printf(m, "%s:%u [%s]%s =%s \"",
+               dp->filename, dp->lineno,
+               iter->table->mod_name, dp->function,
+               ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
        seq_escape(m, dp->format, "\t\r\n\"");
        seq_puts(m, "\"\n");