5 files changed, 11 insertions, 23 deletions

diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 11487b6e7127..561e2a77805c 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -59,10 +59,14 @@ static inline void delayacct_tsk_init(struct task_struct *tsk)
                 __delayacct_tsk_init(tsk);
 }
 
-static inline void delayacct_tsk_exit(struct task_struct *tsk)
+/* Free tsk->delays. Called from bad fork and __put_task_struct
+ * where there's no risk of tsk->delays being accessed elsewhere
+ */
+static inline void delayacct_tsk_free(struct task_struct *tsk)
 {
         if (tsk->delays)
-                __delayacct_tsk_exit(tsk);
+                kmem_cache_free(delayacct_cache, tsk->delays);
+        tsk->delays = NULL;
 }
 
 static inline void delayacct_blkio_start(void)
@@ -101,7 +105,7 @@ static inline void delayacct_init(void)
 {}
 static inline void delayacct_tsk_init(struct task_struct *tsk)
 {}
-static inline void delayacct_tsk_exit(struct task_struct *tsk)
+static inline void delayacct_tsk_free(struct task_struct *tsk)
 {}
 static inline void delayacct_blkio_start(void)
 {}
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6674fc1e51bf..34ed0d99b1bd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -994,7 +994,6 @@ struct task_struct {
          */
         struct pipe_inode_info *splice_pipe;
 #ifdef  CONFIG_TASK_DELAY_ACCT
-        spinlock_t delays_lock;
         struct task_delay_info *delays;
 #endif
 };
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index 57ca3730205d..36752f124c6a 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -41,24 +41,11 @@ void delayacct_init(void)
 
 void __delayacct_tsk_init(struct task_struct *tsk)
 {
-        spin_lock_init(&tsk->delays_lock);
-        /* No need to acquire tsk->delays_lock for allocation here unless
-           __delayacct_tsk_init called after tsk is attached to tasklist
-        */
         tsk->delays = kmem_cache_zalloc(delayacct_cache, SLAB_KERNEL);
         if (tsk->delays)
                 spin_lock_init(&tsk->delays->lock);
 }
 
-void __delayacct_tsk_exit(struct task_struct *tsk)
-{
-        struct task_delay_info *delays = tsk->delays;
-        spin_lock(&tsk->delays_lock);
-        tsk->delays = NULL;
-        spin_unlock(&tsk->delays_lock);
-        kmem_cache_free(delayacct_cache, delays);
-}
-
 /*
  * Start accounting for a delay statistic using
  * its starting timestamp (@start)
@@ -118,8 +105,6 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
         struct timespec ts;
         unsigned long t1,t2,t3;
 
-        spin_lock(&tsk->delays_lock);
-
         /* Though tsk->delays accessed later, early exit avoids
          * unnecessary returning of other data
          */
@@ -161,7 +146,6 @@ int __delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
         spin_unlock(&tsk->delays->lock);
 
 done:
-        spin_unlock(&tsk->delays_lock);
         return 0;
 }
 
diff --git a/kernel/exit.c b/kernel/exit.c
index dba194a8d416..a4c19a52ce46 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -908,7 +908,6 @@ fastcall NORET_TYPE void do_exit(long code)
                 audit_free(tsk);
         taskstats_exit_send(tsk, tidstats, group_dead, mycpu);
         taskstats_exit_free(tidstats);
-        delayacct_tsk_exit(tsk);
 
         exit_mm(tsk);
 
diff --git a/kernel/fork.c b/kernel/fork.c
index aa36c43783cc..f9b014e3e700 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -117,6 +117,7 @@ void __put_task_struct(struct task_struct *tsk)
         security_task_free(tsk);
         free_uid(tsk->user);
         put_group_info(tsk->group_info);
+        delayacct_tsk_free(tsk);
 
         if (!profile_handoff_task(tsk))
                 free_task(tsk);
@@ -1011,7 +1012,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         retval = -EFAULT;
         if (clone_flags & CLONE_PARENT_SETTID)
                 if (put_user(p->pid, parent_tidptr))
-                        goto bad_fork_cleanup;
+                        goto bad_fork_cleanup_delays_binfmt;
 
         INIT_LIST_HEAD(&p->children);
         INIT_LIST_HEAD(&p->sibling);
@@ -1277,7 +1278,8 @@ bad_fork_cleanup_policy:
 bad_fork_cleanup_cpuset:
 #endif
         cpuset_exit(p);
-bad_fork_cleanup:
+bad_fork_cleanup_delays_binfmt:
+        delayacct_tsk_free(p);
         if (p->binfmt)
                 module_put(p->binfmt->module);
 bad_fork_cleanup_put_domain: