Revert "misc: uidstat: avoid create_stat() race and blockage."

This reverts commit f7a812174033fe620509e6e8ca7022abd924b1c4.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

1 files changed, 21 insertions, 31 deletions

diff --git a/drivers/misc/uid_stat.c b/drivers/misc/uid_stat.c
index 509822c81e97..2141124a6c12 100644
--- a/drivers/misc/uid_stat.c
+++ b/drivers/misc/uid_stat.c
@@ -38,13 +38,17 @@ struct uid_stat {
 };
 
 static struct uid_stat *find_uid_stat(uid_t uid) {
+	unsigned long flags;
 	struct uid_stat *entry;
 
+	spin_lock_irqsave(&uid_lock, flags);
 	list_for_each_entry(entry, &uid_list, link) {
 		if (entry->uid == uid) {
+			spin_unlock_irqrestore(&uid_lock, flags);
 			return entry;
 		}
 	}
+	spin_unlock_irqrestore(&uid_lock, flags);
 	return NULL;
 }
 
@@ -86,10 +90,13 @@ static int tcp_rcv_read_proc(char *page, char **start, off_t off,
 
 /* Create a new entry for tracking the specified uid. */
 static struct uid_stat *create_stat(uid_t uid) {
+	unsigned long flags;
+	char uid_s[32];
 	struct uid_stat *new_uid;
+	struct proc_dir_entry *entry;
+
 	/* Create the uid stat struct and append it to the list. */
-	new_uid = kmalloc(sizeof(struct uid_stat), GFP_ATOMIC);
-	if (!new_uid)
+	if ((new_uid = kmalloc(sizeof(struct uid_stat), GFP_KERNEL)) == NULL)
 		return NULL;
 
 	new_uid->uid = uid;
@@ -97,15 +104,11 @@ static struct uid_stat *create_stat(uid_t uid) {
 	atomic_set(&new_uid->tcp_rcv, INT_MIN);
 	atomic_set(&new_uid->tcp_snd, INT_MIN);
 
+	spin_lock_irqsave(&uid_lock, flags);
 	list_add_tail(&new_uid->link, &uid_list);
-	return new_uid;
-}
+	spin_unlock_irqrestore(&uid_lock, flags);
 
-static void create_stat_proc(struct uid_stat *new_uid)
-{
-	char uid_s[32];
-	struct proc_dir_entry *entry;
-	sprintf(uid_s, "%d", new_uid->uid);
+	sprintf(uid_s, "%d", uid);
 	entry = proc_mkdir(uid_s, parent);
 
 	/* Keep reference to uid_stat so we know what uid to read stats from. */
@@ -114,31 +117,17 @@ static void create_stat_proc(struct uid_stat *new_uid)
 
 	create_proc_read_entry("tcp_rcv", S_IRUGO, entry, tcp_rcv_read_proc,
 		(void *) new_uid);
-}
 
-static struct uid_stat *find_or_create_uid_stat(uid_t uid)
-{
-	struct uid_stat *entry;
-	unsigned long flags;
-	spin_lock_irqsave(&uid_lock, flags);
-	entry = find_uid_stat(uid);
-	if (entry) {
-		spin_unlock_irqrestore(&uid_lock, flags);
-		return entry;
-	}
-	entry = create_stat(uid);
-	spin_unlock_irqrestore(&uid_lock, flags);
-	if (entry)
-		create_stat_proc(entry);
-	return entry;
+	return new_uid;
 }
 
 int uid_stat_tcp_snd(uid_t uid, int size) {
 	struct uid_stat *entry;
 	activity_stats_update();
-	entry = find_or_create_uid_stat(uid);
-	if (!entry)
-		return -1;
+	if ((entry = find_uid_stat(uid)) == NULL &&
+		((entry = create_stat(uid)) == NULL)) {
+			return -1;
+	}
 	atomic_add(size, &entry->tcp_snd);
 	return 0;
 }
@@ -146,9 +135,10 @@ int uid_stat_tcp_snd(uid_t uid, int size) {
 int uid_stat_tcp_rcv(uid_t uid, int size) {
 	struct uid_stat *entry;
 	activity_stats_update();
-	entry = find_or_create_uid_stat(uid);
-	if (!entry)
-		return -1;
+	if ((entry = find_uid_stat(uid)) == NULL &&
+		((entry = create_stat(uid)) == NULL)) {
+			return -1;
+	}
 	atomic_add(size, &entry->tcp_rcv);
 	return 0;
 }