Le 20/03/2025 à 19:51, Jim Cromie a écrit :
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.
Like the previous patch: I think this should be a separate series.
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 */
s/cuz/because/
+ 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)
Why do you remove the unlikely here?
return __dynamic_emit_prefix(desc, buf);
return buf;
}
--
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
