[PATCH 17/25] dynamic_debug: hoist locking in ddebug_change to callers

Jim Cromie
2011-07-25T21:43:49Z

Hoist locking out of ddebug_change() and ddebug_save_pending()
into ddebug_exec_query().

ddebug_add_module() also calls ddebug_change() via apply_pending_queries(),
move that call inside the critical section protecting list_add_tail()

Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
---
lib/dynamic_debug.c | 11 ++++-------
1 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 05773c8..396ffb4 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -175,7 +175,7 @@ static bool query_matches_callsite(struct _ddebug *dp,
* Search the tables for _ddebug's which match the given
* `query' and apply the `flags' and `mask' to them. Tells
* the user which ddebug's were changed, or whether none
- * were matched.
+ * were matched. Called with ddebug_lock held.
*/
static int ddebug_change(const struct ddebug_query *query,
unsigned int flags, unsigned int mask)
@@ -187,7 +187,6 @@ static int ddebug_change(const struct ddebug_query *query,
char flagbuf[8];

/* search for matching ddebugs */
- mutex_lock(&ddebug_lock);
list_for_each_entry(dt, &ddebug_tables, link) {

/* match against the module name */
@@ -218,8 +217,6 @@ static int ddebug_change(const struct ddebug_query *query,
sizeof(flagbuf)));
}
}
- mutex_unlock(&ddebug_lock);
-
return nfound;
}

@@ -531,10 +528,8 @@ static int ddebug_save_pending(struct ddebug_query *query,
pq->flags = flags;
pq->mask = mask;

- mutex_lock(&ddebug_lock);
list_add(&pq->link, &pending_queries);
pending_ct++;
- mutex_unlock(&ddebug_lock);

pr_debug("query saved as pending %d\n", pending_ct);
return 0;
@@ -558,6 +553,7 @@ static int ddebug_exec_query(char *query_string)
return -EINVAL;

/* actually go and implement the change */
+ mutex_lock(&ddebug_lock);
nfound = ddebug_change(&query, flags, mask);
qstr = show_ddebug_query(&query);
pr_debug("nfound %d on %s\n", nfound, qstr);
@@ -568,6 +564,7 @@ static int ddebug_exec_query(char *query_string)
pr_warn("no match on: %s\n", qstr);
}
kfree(qstr);
+ mutex_unlock(&ddebug_lock);
return rc;
}

@@ -910,7 +907,7 @@ static const struct file_operations ddebug_proc_fops = {
.write = ddebug_proc_write
};

-/* apply matching queries in pending-queries list */
+/* apply matching queries in pending-queries list. Called with lock held */
static void apply_pending_queries(struct ddebug_table *dt)
{
struct pending_query *pq, *pqnext;
--
1.7.4.1