uti: futex_wait: Use kmalloc area for wait queue

Change-Id: Ida994c87334f9613bbf5cbda45b6b5474fd4c6be

kernel/futex.c

@@ -87,38 +87,6 @@
 
 unsigned long ihk_mc_get_ns_per_tsc(void);
 
-/**
- * struct futex_q - The hashed futex queue entry, one per waiting task
- * @task:		the task waiting on the futex
- * @lock_ptr:		the hash bucket lock
- * @key:		the key the futex is hashed on
- * @requeue_pi_key:	the requeue_pi target futex key
- * @bitset:		bitset for the optional bitmasked wakeup
- *
- * We use this hashed waitqueue, instead of a normal wait_queue_t, so
- * we can wake only the relevant ones (hashed queues may be shared).
- *
- * A futex_q has a woken state, just like tasks have TASK_RUNNING.
- * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0.
- * The order of wakup is always to make the first condition true, then
- * the second.
- *
- * PI futexes are typically woken before they are removed from the hash list via
- * the rt_mutex code. See unqueue_me_pi().
- */
-struct futex_q {
-	struct plist_node list;
-
-	struct thread *task;
-	ihk_spinlock_t *lock_ptr;
-	union futex_key key;
-	union futex_key *requeue_pi_key;
-	uint32_t bitset;
-
-	/* Used to wake-up a thread running on a Linux CPU */
-	void *uti_futex_resp; 
-};
-
 /*
  * Hash buckets are shared by all the futex_keys that hash to the same
  * location.  Each key may have multiple futex_q structures, one for each task
@@ -825,13 +793,22 @@ static int futex_wait(uint32_t __user *uaddr, int fshared,
 		      struct cpu_local_var *clv_override)
 {
 	struct futex_hash_bucket *hb;
-	struct futex_q q;
 	int64_t time_remain;
+	struct futex_q lq;
+	struct futex_q *q = NULL;
 	int ret;
 
 	if (!bitset)
 		return -EINVAL;
 
+	if (!clv_override) {
+		q = &lq;
+	}
+	else {
+		q = &cpu_local_var_with_override(current,
+						 clv_override)->futex_q;
+	}
+
 #ifdef PROFILE_ENABLE
 	if (cpu_local_var_with_override(current, clv_override)->profile &&
 		cpu_local_var_with_override(current, clv_override)->profile_start_ts) {
@@ -841,24 +818,25 @@ static int futex_wait(uint32_t __user *uaddr, int fshared,
 	}
 #endif
 
-	q.bitset = bitset;
+	q->bitset = bitset;
-	q.requeue_pi_key = NULL;
+	q->requeue_pi_key = NULL;
-	q.uti_futex_resp = cpu_local_var_with_override(uti_futex_resp, clv_override);
+	q->uti_futex_resp = cpu_local_var_with_override(uti_futex_resp,
+							clv_override);
 
 retry:
 	/* Prepare to wait on uaddr. */
-	ret = futex_wait_setup(uaddr, val, fshared, &q, &hb, clv_override);
+	ret = futex_wait_setup(uaddr, val, fshared, q, &hb, clv_override);
 	if (ret) {
 		uti_dkprintf("%s: tid=%d futex_wait_setup returns zero, no need to sleep\n", __FUNCTION__, cpu_local_var_with_override(current, clv_override)->tid);
 		goto out;
 	}
 
 	/* queue_me and wait for wakeup, timeout, or a signal. */
-	time_remain = futex_wait_queue_me(hb, &q, timeout, clv_override);
+	time_remain = futex_wait_queue_me(hb, q, timeout, clv_override);
 
 	/* If we were woken (and unqueued), we succeeded, whatever. */
 	ret = 0;
-	if (!unqueue_me(&q)) {
+	if (!unqueue_me(q)) {
 		uti_dkprintf("%s: tid=%d unqueued\n", __FUNCTION__, cpu_local_var_with_override(current, clv_override)->tid);
 		goto out_put_key;
 	}
@@ -878,11 +856,11 @@ retry:
 	}
 
 	/* RIKEN: no signals */
-	put_futex_key(fshared, &q.key);
+	put_futex_key(fshared, &q->key);
 	goto retry;
 
 out_put_key:
-	put_futex_key(fshared, &q.key);
+	put_futex_key(fshared, &q->key);
 out:
 #ifdef PROFILE_ENABLE
 	if (cpu_local_var_with_override(current, clv_override)->profile) {

kernel/include/futex.h

@@ -94,6 +94,7 @@
 #include <list.h>
 #include <process.h>
 #include <waitq.h>
+#include <plist.h>
 
 #ifndef _ASM_X86_FUTEX_H
 #define _ASM_X86_FUTEX_H
@@ -165,5 +166,37 @@ futex(
 );
 
 
+/**
+ * struct futex_q - The hashed futex queue entry, one per waiting task
+ * @task:		the task waiting on the futex
+ * @lock_ptr:		the hash bucket lock
+ * @key:		the key the futex is hashed on
+ * @requeue_pi_key:	the requeue_pi target futex key
+ * @bitset:		bitset for the optional bitmasked wakeup
+ *
+ * We use this hashed waitqueue, instead of a normal wait_queue_t, so
+ * we can wake only the relevant ones (hashed queues may be shared).
+ *
+ * A futex_q has a woken state, just like tasks have TASK_RUNNING.
+ * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0.
+ * The order of wakup is always to make the first condition true, then
+ * the second.
+ *
+ * PI futexes are typically woken before they are removed from the hash list via
+ * the rt_mutex code. See unqueue_me_pi().
+ */
+struct futex_q {
+	struct plist_node list;
+
+	struct thread *task;
+	ihk_spinlock_t *lock_ptr;
+	union futex_key key;
+	union futex_key *requeue_pi_key;
+	uint32_t bitset;
+
+	/* Used to wake-up a thread running on a Linux CPU */
+	void *uti_futex_resp;
+};
+
 #endif
 #endif

kernel/include/process.h

@@ -717,6 +717,7 @@ struct thread {
 	struct uti_attr *mod_clone_arg;
 	int parent_cpuid;
 	int uti_refill_tid;
+	struct futex_q futex_q;
 
 	// for performance counter
 	unsigned long pmc_alloc_map;