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

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This reverts commit f7a8121740.

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
This commit is contained in:
Amit Pundir 2016-04-25 17:00:43 +05:30
parent d9e6431c6c
commit e9edcb0046
1 changed files with 21 additions and 31 deletions
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52
drivers/misc/uid_stat.c
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@ -38,13 +38,17 @@ struct uid_stat {
}; };
static struct uid_stat *find_uid_stat(uid_t uid) { static struct uid_stat *find_uid_stat(uid_t uid) {
unsigned long flags;
struct uid_stat *entry; struct uid_stat *entry;
spin_lock_irqsave(&uid_lock, flags);
list_for_each_entry(entry, &uid_list, link) { list_for_each_entry(entry, &uid_list, link) {
if (entry->uid == uid) { if (entry->uid == uid) {
spin_unlock_irqrestore(&uid_lock, flags);
return entry; return entry;
} }
} }
spin_unlock_irqrestore(&uid_lock, flags);
return NULL; 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. */ /* Create a new entry for tracking the specified uid. */
static struct uid_stat *create_stat(uid_t uid) { static struct uid_stat *create_stat(uid_t uid) {
unsigned long flags;
char uid_s[32];
struct uid_stat *new_uid; struct uid_stat *new_uid;
struct proc_dir_entry *entry;
/* Create the uid stat struct and append it to the list. */ /* Create the uid stat struct and append it to the list. */
new_uid = kmalloc(sizeof(struct uid_stat), GFP_ATOMIC); if ((new_uid = kmalloc(sizeof(struct uid_stat), GFP_KERNEL)) == NULL)
if (!new_uid)
return NULL; return NULL;
new_uid->uid = uid; 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_rcv, INT_MIN);
atomic_set(&new_uid->tcp_snd, INT_MIN); atomic_set(&new_uid->tcp_snd, INT_MIN);
spin_lock_irqsave(&uid_lock, flags);
list_add_tail(&new_uid->link, &uid_list); 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) sprintf(uid_s, "%d", uid);
{
char uid_s[32];
struct proc_dir_entry *entry;
sprintf(uid_s, "%d", new_uid->uid);
entry = proc_mkdir(uid_s, parent); entry = proc_mkdir(uid_s, parent);
/* Keep reference to uid_stat so we know what uid to read stats from. */ /* 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, create_proc_read_entry("tcp_rcv", S_IRUGO, entry, tcp_rcv_read_proc,
(void *) new_uid); (void *) new_uid);
}
static struct uid_stat *find_or_create_uid_stat(uid_t uid) return new_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;
} }
int uid_stat_tcp_snd(uid_t uid, int size) { int uid_stat_tcp_snd(uid_t uid, int size) {
struct uid_stat *entry; struct uid_stat *entry;
activity_stats_update(); activity_stats_update();
entry = find_or_create_uid_stat(uid); if ((entry = find_uid_stat(uid)) == NULL &&
if (!entry) ((entry = create_stat(uid)) == NULL)) {
return -1; return -1;
}
atomic_add(size, &entry->tcp_snd); atomic_add(size, &entry->tcp_snd);
return 0; 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) { int uid_stat_tcp_rcv(uid_t uid, int size) {
struct uid_stat *entry; struct uid_stat *entry;
activity_stats_update(); activity_stats_update();
entry = find_or_create_uid_stat(uid); if ((entry = find_uid_stat(uid)) == NULL &&
if (!entry) ((entry = create_stat(uid)) == NULL)) {
return -1; return -1;
}
atomic_add(size, &entry->tcp_rcv); atomic_add(size, &entry->tcp_rcv);
return 0; return 0;
} }