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Date: Mon, 11 Jul 2011 01:46:49 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: jbaron@...hat.com
Cc: linux-kernel@...r.kernel.org, bvanassche@....org, joe@...ches.com,
gregkh@...e.de, gnb@...h.org, Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH 14/21] dynamic_debug: hoist locking in ddebug_change to callers
Hoist locking out of ddebug_change(), into ddebug_exec_query(),
and fix return from inside the critical section.
Remove locking in ddebug_save_pending(), since its also
protected by 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@...il.com>
---
lib/dynamic_debug.c | 37 ++++++++++++++-----------------------
1 files changed, 14 insertions(+), 23 deletions(-)
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 0faac83..d115f52 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -168,7 +168,7 @@ static int 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)
@@ -180,7 +180,6 @@ 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 */
@@ -212,8 +211,6 @@ static int ddebug_change(const struct ddebug_query *query,
sizeof(flagbuf)));
}
}
- mutex_unlock(&ddebug_lock);
-
return nfound;
}
@@ -475,8 +472,8 @@ static int queries_match(struct ddebug_query *q1, struct ddebug_query *q2)
return 1;
}
-/* copy query off stack, save flags & mask, and store in pending-list,
- after checking that query isnt already there
+/* copy query off stack, save flags & mask, and store or update in
+ pending-list. Called with ddebug_lock held.
*/
static int ddebug_save_pending(struct ddebug_query *query,
unsigned int flags, unsigned int mask)
@@ -499,7 +496,6 @@ static int ddebug_save_pending(struct ddebug_query *query,
if (verbose)
pr_info("add to pending: %s\n", show_ddebug_query(query));
- pending_ct++;
pq = kzalloc(sizeof(struct pending_query), GFP_KERNEL);
if (pq == NULL)
return -ENOMEM;
@@ -517,9 +513,8 @@ 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);
- mutex_unlock(&ddebug_lock);
+ pending_ct++;
if (verbose)
pr_info("query saved as pending %d\n", pending_ct);
@@ -533,7 +528,7 @@ static int ddebug_exec_query(char *query_string)
#define MAXWORDS 9
int nwords;
char *words[MAXWORDS];
- int nfound;
+ int nfound, rc = 0;
nwords = ddebug_tokenize(query_string, words, MAXWORDS);
if (nwords <= 0)
@@ -544,17 +539,18 @@ 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);
-
- pr_info("nfound %d on %s\n", nfound, show_ddebug_query(&query));
if (!nfound) {
if (flags & _DPRINTK_FLAGS_APPEND)
- return ddebug_save_pending(&query, flags, mask);
+ rc = ddebug_save_pending(&query, flags, mask);
else
pr_warn("no match on: %s\n",
show_ddebug_query(&query));
}
- return 0;
+ mutex_unlock(&ddebug_lock);
+ pr_info("nfound %d on %s\n", nfound, show_ddebug_query(&query));
+ return rc;
}
/* handle multiple queries, continue on error, return last error */
@@ -904,7 +900,7 @@ 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;
@@ -914,7 +910,6 @@ static void apply_pending_queries(struct ddebug_table *dt)
pr_info("pending_ct: %d\n", pending_ct);
list_for_each_entry_safe(pq, pqnext, &pending_queries, link) {
-
if (verbose)
pr_info("check: %s <-> %s\n",
dt->mod_name, show_pending_query(pq));
@@ -922,15 +917,12 @@ static void apply_pending_queries(struct ddebug_table *dt)
nfound = ddebug_change(&pq->query, pq->flags, pq->mask);
if (nfound) {
- mutex_lock(&ddebug_lock);
list_del(&pq->link);
- mutex_unlock(&ddebug_lock);
kfree(pq);
pending_ct--;
} else if (verbose)
pr_info("no-match: %s\n", show_pending_query(pq));
}
-
}
/*
* Allocate a new ddebug_table for the given module
@@ -954,14 +946,13 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
dt->num_ddebugs = n;
dt->ddebugs = tab;
- mutex_lock(&ddebug_lock);
- list_add_tail(&dt->link, &ddebug_tables);
- mutex_unlock(&ddebug_lock);
-
if (verbose)
pr_info("%u debug prints in module %s\n", n, dt->mod_name);
+ mutex_lock(&ddebug_lock);
+ list_add_tail(&dt->link, &ddebug_tables);
apply_pending_queries(dt);
+ mutex_unlock(&ddebug_lock);
return 0;
}
--
1.7.4.1
--
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