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From:   Jim Cromie <jim.cromie@gmail.com>
To:     Jason Baron <jbaron@akamai.com>, linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, Jim Cromie <jim.cromie@gmail.com>
Subject: [RFC PATCH v5 14/28] dyndbg: add ddebug_site(_get|_put) abstraction
Date:   Tue, 11 May 2021 12:50:43 -0600
Message-Id: <20210511185057.3815777-15-jim.cromie@gmail.com>
In-Reply-To: <20210511185057.3815777-1-jim.cromie@gmail.com>
References: <20210511185057.3815777-1-jim.cromie@gmail.com>
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Replace direct ->site refs with _get(),_put() internal API.  Right
now, _get() just returns ->site and _put() does nothing.  Later we can
replace this implementation with one using ->_index to fetch site data
then forget or keep it selectively.

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
 lib/dynamic_debug.c | 31 +++++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 1441b31915e7..90bea97c0da1 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -144,6 +144,14 @@ static void vpr_info_dq(const struct ddebug_query *query, const char *msg)
 		 query->first_lineno, query->last_lineno);
 }
 
+static struct _ddebug_site *ddebug_site_get(struct _ddebug *dp)
+{
+	return dp->site; /* passthru abstraction */
+}
+static inline void ddebug_site_put(struct _ddebug *dp)
+{
+}
+
 static int ddebug_match_site(const struct ddebug_query *query,
 			     const struct _ddebug *dp,
 			     const struct _ddebug_site *dc)
@@ -239,16 +247,18 @@ static int ddebug_change(const struct ddebug_query *query,
 
 		for (i = 0; i < dt->num_ddebugs; i++) {
 			struct _ddebug *dp = &dt->ddebugs[i];
-			struct _ddebug_site *dc = dp->site;
+			struct _ddebug_site *dc;
+
+			dc = ddebug_site_get(dp);
 
 			if (!ddebug_match_site(query, dp, dc))
-				continue;
+				goto skipsite;
 
 			nfound++;
 
 			newflags = (dp->flags & modifiers->mask) | modifiers->flags;
 			if (newflags == dp->flags)
-				continue;
+				goto skipsite;
 
 			ddebug_alter_site(dp, modifiers);
 
@@ -264,6 +274,9 @@ static int ddebug_change(const struct ddebug_query *query,
 					  dt->mod_name, dp->lineno,
 					  ddebug_describe_flags(dp->flags, &fbuf),
 					  dp->format);
+
+skipsite:
+			ddebug_site_put(dp);
 		}
 	}
 	mutex_unlock(&ddebug_lock);
@@ -633,11 +646,11 @@ static int remaining(int wrote)
 	return 0;
 }
 
-static char *__dynamic_emit_prefix(const struct _ddebug *dp, char *buf)
+static char *__dynamic_emit_prefix(struct _ddebug *dp, char *buf)
 {
 	int pos_after_tid;
 	int pos = 0;
-	const struct _ddebug_site *desc = dp->site;
+	const struct _ddebug_site *desc;
 
 	if (dp->flags & _DPRINTK_FLAGS_INCL_TID) {
 		if (in_interrupt())
@@ -648,6 +661,7 @@ static char *__dynamic_emit_prefix(const struct _ddebug *dp, char *buf)
 	}
 	pos_after_tid = pos;
 
+	desc = ddebug_site_get(dp);
 	if (desc) {
 		if (dp->flags & _DPRINTK_FLAGS_INCL_MODNAME)
 			pos += snprintf(buf + pos, remaining(pos), "%s:",
@@ -665,6 +679,8 @@ static char *__dynamic_emit_prefix(const struct _ddebug *dp, char *buf)
 	if (pos >= PREFIX_SIZE)
 		buf[PREFIX_SIZE - 1] = '\0';
 
+	ddebug_site_put(dp);
+
 	return buf;
 }
 
@@ -947,7 +963,8 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
 		return 0;
 	}
 
-	dc = dp->site;
+	dc = ddebug_site_get(dp);
+
 	if (dc) {
 		seq_printf(m, "%s:%u [%s]%s =%s \"",
 			   trim_prefix(dc->filename), dp->lineno,
@@ -963,6 +980,8 @@ static int ddebug_proc_show(struct seq_file *m, void *p)
 		seq_puts(m, "\"\n");
 	}
 
+	ddebug_site_put(dp);
+
 	return 0;
 }
 
-- 
2.31.1