Signed-off-by: Ola Liljedahl <ola.liljed...@arm.com>
Reviewed-by: Brian Brooks <brian.bro...@arm.com>
---
platform/linux-generic/Makefile.am | 1 +
platform/linux-generic/include/odp_llqueue.h | 309 +++++++++++++++++++++++++++
2 files changed, 310 insertions(+)
create mode 100644 platform/linux-generic/include/odp_llqueue.h
diff --git a/platform/linux-generic/Makefile.am
b/platform/linux-generic/Makefile.am
index b95e691b..3cb7511b 100644
--- a/platform/linux-generic/Makefile.am
+++ b/platform/linux-generic/Makefile.am
@@ -156,6 +156,7 @@ noinst_HEADERS = \
${srcdir}/include/odp_errno_define.h \
${srcdir}/include/odp_forward_typedefs_internal.h \
${srcdir}/include/odp_internal.h \
+ ${srcdir}/include/odp_llqueue.h \
${srcdir}/include/odp_name_table_internal.h \
${srcdir}/include/odp_packet_internal.h \
${srcdir}/include/odp_packet_io_internal.h \
diff --git a/platform/linux-generic/include/odp_llqueue.h
b/platform/linux-generic/include/odp_llqueue.h
new file mode 100644
index 00000000..758af490
--- /dev/null
+++ b/platform/linux-generic/include/odp_llqueue.h
@@ -0,0 +1,309 @@
+/* Copyright (c) 2017, ARM Limited.
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef ODP_LLQUEUE_H_
+#define ODP_LLQUEUE_H_
+
+#include <odp/api/cpu.h>
+#include <odp/api/hints.h>
+#include <odp/api/spinlock.h>
+
+#include <odp_config_internal.h>
+#include <odp_debug_internal.h>
+#include <odp_cpu.h>
+
+#include <stdint.h>
+#include <stdlib.h>
+
+/******************************************************************************
+ * Linked list queues
+ *****************************************************************************/
+
+struct llqueue;
+struct llnode;
+
+static struct llnode *llq_head(struct llqueue *llq);
+static void llqueue_init(struct llqueue *llq);
+static void llq_enqueue(struct llqueue *llq, struct llnode *node);
+static struct llnode *llq_dequeue(struct llqueue *llq);
+static odp_bool_t llq_dequeue_cond(struct llqueue *llq, struct llnode *exp);
+static odp_bool_t llq_cond_rotate(struct llqueue *llq, struct llnode *node);
+static odp_bool_t llq_on_queue(struct llnode *node);
+
+/******************************************************************************
+ * The implementation(s)
+ *****************************************************************************/
+
+#define SENTINEL ((void *)~(uintptr_t)0)
+
+#ifdef CONFIG_LLDSCD
+/* Implement queue operations using double-word LL/SC */
+
+/* The scalar equivalent of a double pointer */
+#if __SIZEOF_PTRDIFF_T__ == 4
+typedef uint64_t dintptr_t;
+#endif
+#if __SIZEOF_PTRDIFF_T__ == 8
+typedef __int128 dintptr_t;
+#endif
+
+struct llnode {
+ struct llnode *next;
+};
+
+union llht {
+ struct {
+ struct llnode *head, *tail;
+ } st;
+ dintptr_t ui;
+};
+
+struct llqueue {
+ union llht u;
+};
+
+static inline struct llnode *llq_head(struct llqueue *llq)
+{
+ return __atomic_load_n(&llq->u.st.head, __ATOMIC_RELAXED);
+}
+
+static inline void llqueue_init(struct llqueue *llq)
+{
+ llq->u.st.head = NULL;
+ llq->u.st.tail = NULL;
+}
+
+static inline void llq_enqueue(struct llqueue *llq, struct llnode *node)
+{
+ union llht old, neu;
+
+ ODP_ASSERT(node->next == NULL);
+ node->next = SENTINEL;
+ do {
+ old.ui = lld(&llq->u.ui, __ATOMIC_RELAXED);
+ neu.st.head = old.st.head == NULL ? node : old.st.head;
+ neu.st.tail = node;
+ } while (odp_unlikely(scd(&llq->u.ui, neu.ui, __ATOMIC_RELEASE)));
+ if (old.st.tail != NULL) {
+ /* List was not empty */
+ ODP_ASSERT(old.st.tail->next == SENTINEL);
+ old.st.tail->next = node;
+ }
+}
+
+static inline struct llnode *llq_dequeue(struct llqueue *llq)
+{
+ struct llnode *head;
+ union llht old, neu;
+
+ /* llq_dequeue() may be used in a busy-waiting fashion
+ * Read head using plain load to avoid disturbing remote LL/SC
+ */
+ head = __atomic_load_n(&llq->u.st.head, __ATOMIC_ACQUIRE);
+ if (head == NULL)
+ return NULL;
+ /* Read head->next before LL to minimize cache miss latency
+ * in LL/SC below
+ */
+ (void)__atomic_load_n(&head->next, __ATOMIC_RELAXED);
+
+ do {
+ old.ui = lld(&llq->u.ui, __ATOMIC_RELAXED);
+ if (odp_unlikely(old.st.head == NULL)) {
+ /* Empty list */
+ return NULL;
+ } else if (odp_unlikely(old.st.head == old.st.tail)) {
+ /* Single-element in list */
+ neu.st.head = NULL;
+ neu.st.tail = NULL;
+ } else {
+ /* Multi-element list, dequeue head */
+ struct llnode *next;
+ /* Wait until llq_enqueue() has written true next
+ * pointer
+ */
+ while ((next = __atomic_load_n(&old.st.head->next,
+ __ATOMIC_RELAXED)) ==
+ SENTINEL)
+ odp_cpu_pause();
+ neu.st.head = next;
+ neu.st.tail = old.st.tail;
+ }
+ } while (odp_unlikely(scd(&llq->u.ui, neu.ui, __ATOMIC_RELAXED)));
+ old.st.head->next = NULL;
+ return old.st.head;
+}
+
+static inline odp_bool_t llq_dequeue_cond(struct llqueue *llq,
+ struct llnode *exp)
+{
+ union llht old, neu;
+
+ do {
+ old.ui = lld(&llq->u.ui, __ATOMIC_ACQUIRE);
+ if (odp_unlikely(old.st.head == NULL || old.st.head != exp)) {
+ /* Empty list or wrong head */
+ return false;
+ } else if (odp_unlikely(old.st.head == old.st.tail)) {
+ /* Single-element in list */
+ neu.st.head = NULL;
+ neu.st.tail = NULL;
+ } else {
+ /* Multi-element list, dequeue head */
+ struct llnode *next;
+
+ /* Wait until llq_enqueue() has written true next
+ * pointer */
+ while ((next = __atomic_load_n(&old.st.head->next,
+ __ATOMIC_RELAXED)) ==
+ SENTINEL)
+ odp_cpu_pause();
+
+ neu.st.head = next;
+ neu.st.tail = old.st.tail;
+ }
+ } while (odp_unlikely(scd(&llq->u.ui, neu.ui, __ATOMIC_RELAXED)));
+ old.st.head->next = NULL;
+ return true;
+}
+
+/* If 'node' is a head of llq then move it to tail */
+static inline odp_bool_t llq_cond_rotate(struct llqueue *llq,
+ struct llnode *node)
+{
+ /* Difficult to make this into a single atomic operation
+ * Instead use existing primitives.
+ */
+ if (odp_likely(llq_dequeue_cond(llq, node))) {
+ llq_enqueue(llq, node);
+ return true;
+ }
+ return false;
+}
+
+static inline odp_bool_t llq_on_queue(struct llnode *node)
+{
+ return node->next != NULL;
+}
+
+#else
+/* Implement queue operations protected by a spin lock */
+
+struct llnode {
+ struct llnode *next;
+};
+
+struct llqueue {
+ struct llnode *head, *tail;
+ odp_spinlock_t lock;
+};
+
+static inline struct llnode *llq_head(struct llqueue *llq)
+{
+ return __atomic_load_n(&llq->head, __ATOMIC_RELAXED);
+}
+
+static inline void llqueue_init(struct llqueue *llq)
+{
+ llq->head = NULL;
+ llq->tail = NULL;
+ odp_spinlock_init(&llq->lock);
+}
+
+static inline void llq_enqueue(struct llqueue *llq, struct llnode *node)
+{
+ ODP_ASSERT(node->next == NULL);
+ node->next = SENTINEL;
+
+ odp_spinlock_lock(&llq->lock);
+ if (llq->head == NULL) {
+ llq->head = node;
+ llq->tail = node;
+ } else {
+ llq->tail->next = node;
+ llq->tail = node;
+ }
+ odp_spinlock_unlock(&llq->lock);
+}
+
+static inline struct llnode *llq_dequeue(struct llqueue *llq)
+{
+ struct llnode *head;
+ struct llnode *node = NULL;
+
+ head = __atomic_load_n(&llq->head, __ATOMIC_RELAXED);
+ if (head == NULL)
+ return NULL;
+
+ odp_spinlock_lock(&llq->lock);
+ if (llq->head != NULL) {
+ node = llq->head;
+ if (llq->head == llq->tail) {
+ ODP_ASSERT(node->next == SENTINEL);
+ llq->head = NULL;
+ llq->tail = NULL;
+ } else {
+ ODP_ASSERT(node->next != SENTINEL);
+ llq->head = node->next;
+ }
+ node->next = NULL;
+ }
+ odp_spinlock_unlock(&llq->lock);
+ return node;
+}
+
+static inline odp_bool_t llq_dequeue_cond(struct llqueue *llq,
+ struct llnode *node)
+{
+ odp_bool_t success = false;
+
+ odp_spinlock_lock(&llq->lock);
+ if (odp_likely(llq->head != NULL && llq->head == node)) {
+ success = true;
+ if (llq->head == llq->tail) {
+ ODP_ASSERT(node->next == SENTINEL);
+ llq->head = NULL;
+ llq->tail = NULL;
+ } else {
+ ODP_ASSERT(node->next != SENTINEL);
+ llq->head = node->next;
+ }
+ node->next = NULL;
+ }
+ odp_spinlock_unlock(&llq->lock);
+ return success;
+}
+
+/* If 'node' is a head of llq then move it to tail */
+static inline odp_bool_t llq_cond_rotate(struct llqueue *llq,
+ struct llnode *node)
+{
+ odp_bool_t success = false;
+
+ odp_spinlock_lock(&llq->lock);
+ if (odp_likely(llq->head == node)) {
+ success = true;
+ if (llq->tail != node) {
+ ODP_ASSERT(node->next != SENTINEL);
+ llq->head = node->next;
+ llq->tail->next = node;
+ llq->tail = node;
+ node->next = SENTINEL;
+ }
+ /* Else 'node' is only element on list => nothing to do */
+ }
+ odp_spinlock_unlock(&llq->lock);
+ return success;
+}
+
+static inline odp_bool_t llq_on_queue(struct llnode *node)
+{
+ return node->next != NULL;
+}
+
+#endif
+
+#endif
--
2.13.1
