[PATCH v2 14/59] dyndbg: split _emit_lookup() out of dynamic_emit_prefix()

[Jim Cromie]

Split dynamic_emit_prefix() to separate out _INCL_LOOKUPs:

1. keep dynamic_emit_prefix() static inline
   check _INCL_ANY flags before calling 2

2. __dynamic_emit_prefix()
   prints [TID] or <intr> and trailing space if +t flag
   check _INCL_LOOKUP flags before calling 3

3. __dynamic_emit_lookup()
   prints ONLY module, function, src, line, and trailing space
   TID isn't "callsite" specific info.
   result is "cacheable"

Notes:

2,3 are gated, only called when theyve something to emit, so they just
add trailing space.  This obsoletes the pos_after_tid var and logic.

__dynamic_emit_lookup() adds line too, so the result is "whole".
While this would enlarge a naive cache vs add-line-after-caching, we
dont even have a naive one yet.

And some clever indexing on store() might be able to fold the flags
setting in, such that the prefix stored with +mf flags only (-l),
could be returned for all pr_debugs in that function which also had
+mf flags. While still supporting +mfsl prefixes (with cache
expansion) as they're used.

Signed-off-by: Jim Cromie <jim.cro...@gmail.com>
---
 lib/dynamic_debug.c | 40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 663c125006d0..f7ec2365ab40 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -850,19 +850,8 @@ static int remaining(int wrote)
        return 0;
 }
 
-static char *__dynamic_emit_prefix(const struct _ddebug *desc, char *buf)
+static int __dynamic_emit_lookup(const struct _ddebug *desc, char *buf, int 
pos)
 {
-       int pos_after_tid;
-       int pos = 0;
-
-       if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
-               if (in_interrupt())
-                       pos += snprintf(buf + pos, remaining(pos), "<intr> ");
-               else
-                       pos += snprintf(buf + pos, remaining(pos), "[%d] ",
-                                       task_pid_vnr(current));
-       }
-       pos_after_tid = pos;
        if (desc->flags & _DPRINTK_FLAGS_INCL_MODNAME)
                pos += snprintf(buf + pos, remaining(pos), "%s:",
                                desc->modname);
@@ -875,8 +864,29 @@ static char *__dynamic_emit_prefix(const struct _ddebug 
*desc, char *buf)
        if (desc->flags & _DPRINTK_FLAGS_INCL_LINENO)
                pos += snprintf(buf + pos, remaining(pos), "%d:",
                                desc->lineno);
-       if (pos - pos_after_tid)
-               pos += snprintf(buf + pos, remaining(pos), " ");
+
+       /* cuz LOOKUP, we've emitted, so add trailing space if room */
+       if (remaining(pos))
+               buf[pos++] = ' ';
+
+       return pos;
+}
+
+static char *__dynamic_emit_prefix(struct _ddebug *desc, char *buf)
+{
+       int pos = 0;
+
+       if (desc->flags & _DPRINTK_FLAGS_INCL_TID) {
+               if (in_interrupt())
+                       pos += snprintf(buf + pos, remaining(pos), "<intr> ");
+               else
+                       pos += snprintf(buf + pos, remaining(pos), "[%d] ",
+                                       task_pid_vnr(current));
+       }
+
+       if (unlikely(desc->flags & _DPRINTK_FLAGS_INCL_LOOKUP))
+               pos += __dynamic_emit_lookup(desc, buf, pos);
+
        if (pos >= PREFIX_SIZE)
                buf[PREFIX_SIZE - 1] = '\0';
 
@@ -885,7 +895,7 @@ static char *__dynamic_emit_prefix(const struct _ddebug 
*desc, char *buf)
 
 static inline char *dynamic_emit_prefix(struct _ddebug *desc, char *buf)
 {
-       if (unlikely(desc->flags & _DPRINTK_FLAGS_INCL_ANY))
+       if (desc->flags & _DPRINTK_FLAGS_INCL_ANY)
                return __dynamic_emit_prefix(desc, buf);
        return buf;
 }
-- 
2.49.0