enic: use atomic_t instead of spin_lock in busy poll
We use spinlock to access a single flag. We can avoid spin_locks by using atomic variable and atomic_cmpxchg(). Use atomic_cmpxchg to set the flag for idle to poll. And a simple atomic_set to unlock (set idle from poll). In napi poll, if gro is enabled, we call napi_gro_receive() to deliver the packets. Before we call napi_complete(), i.e while re-polling, if low latency busy poll is called, we use netif_receive_skb() to deliver the packets. At this point if there are some skb's held in GRO, busy poll could deliver the packets out of order. So we call napi_gro_flush() to flush skbs before we move the napi poll to idle. Signed-off-by: Govindarajulu Varadarajan <_govind@gmx.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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1298267b54
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@ -1208,7 +1208,7 @@ static int enic_poll(struct napi_struct *napi, int budget)
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napi_complete(napi);
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vnic_intr_unmask(&enic->intr[intr]);
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}
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enic_poll_unlock_napi(&enic->rq[cq_rq]);
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enic_poll_unlock_napi(&enic->rq[cq_rq], napi);
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return rq_work_done;
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}
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@ -1414,7 +1414,7 @@ static int enic_poll_msix_rq(struct napi_struct *napi, int budget)
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*/
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enic_calc_int_moderation(enic, &enic->rq[rq]);
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enic_poll_unlock_napi(&enic->rq[rq]);
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enic_poll_unlock_napi(&enic->rq[rq], napi);
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if (work_done < work_to_do) {
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/* Some work done, but not enough to stay in polling,
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@ -21,6 +21,7 @@
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#define _VNIC_RQ_H_
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#include <linux/pci.h>
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#include <linux/netdevice.h>
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#include "vnic_dev.h"
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#include "vnic_cq.h"
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@ -75,6 +76,12 @@ struct vnic_rq_buf {
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uint64_t wr_id;
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};
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enum enic_poll_state {
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ENIC_POLL_STATE_IDLE,
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ENIC_POLL_STATE_NAPI,
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ENIC_POLL_STATE_POLL
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};
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struct vnic_rq {
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unsigned int index;
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struct vnic_dev *vdev;
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@ -86,19 +93,7 @@ struct vnic_rq {
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void *os_buf_head;
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unsigned int pkts_outstanding;
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#ifdef CONFIG_NET_RX_BUSY_POLL
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#define ENIC_POLL_STATE_IDLE 0
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#define ENIC_POLL_STATE_NAPI (1 << 0) /* NAPI owns this poll */
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#define ENIC_POLL_STATE_POLL (1 << 1) /* poll owns this poll */
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#define ENIC_POLL_STATE_NAPI_YIELD (1 << 2) /* NAPI yielded this poll */
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#define ENIC_POLL_STATE_POLL_YIELD (1 << 3) /* poll yielded this poll */
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#define ENIC_POLL_YIELD (ENIC_POLL_STATE_NAPI_YIELD | \
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ENIC_POLL_STATE_POLL_YIELD)
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#define ENIC_POLL_LOCKED (ENIC_POLL_STATE_NAPI | \
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ENIC_POLL_STATE_POLL)
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#define ENIC_POLL_USER_PEND (ENIC_POLL_STATE_POLL | \
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ENIC_POLL_STATE_POLL_YIELD)
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unsigned int bpoll_state;
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spinlock_t bpoll_lock;
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atomic_t bpoll_state;
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#endif /* CONFIG_NET_RX_BUSY_POLL */
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};
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@ -215,76 +210,43 @@ static inline int vnic_rq_fill(struct vnic_rq *rq,
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#ifdef CONFIG_NET_RX_BUSY_POLL
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static inline void enic_busy_poll_init_lock(struct vnic_rq *rq)
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{
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spin_lock_init(&rq->bpoll_lock);
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rq->bpoll_state = ENIC_POLL_STATE_IDLE;
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atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE);
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}
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static inline bool enic_poll_lock_napi(struct vnic_rq *rq)
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{
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bool rc = true;
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int rc = atomic_cmpxchg(&rq->bpoll_state, ENIC_POLL_STATE_IDLE,
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ENIC_POLL_STATE_NAPI);
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spin_lock(&rq->bpoll_lock);
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if (rq->bpoll_state & ENIC_POLL_LOCKED) {
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WARN_ON(rq->bpoll_state & ENIC_POLL_STATE_NAPI);
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rq->bpoll_state |= ENIC_POLL_STATE_NAPI_YIELD;
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rc = false;
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} else {
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rq->bpoll_state = ENIC_POLL_STATE_NAPI;
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}
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spin_unlock(&rq->bpoll_lock);
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return rc;
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return (rc == ENIC_POLL_STATE_IDLE);
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}
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static inline bool enic_poll_unlock_napi(struct vnic_rq *rq)
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static inline void enic_poll_unlock_napi(struct vnic_rq *rq,
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struct napi_struct *napi)
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{
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bool rc = false;
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spin_lock(&rq->bpoll_lock);
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WARN_ON(rq->bpoll_state &
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(ENIC_POLL_STATE_POLL | ENIC_POLL_STATE_NAPI_YIELD));
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if (rq->bpoll_state & ENIC_POLL_STATE_POLL_YIELD)
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rc = true;
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rq->bpoll_state = ENIC_POLL_STATE_IDLE;
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spin_unlock(&rq->bpoll_lock);
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return rc;
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WARN_ON(atomic_read(&rq->bpoll_state) != ENIC_POLL_STATE_NAPI);
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napi_gro_flush(napi, false);
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atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE);
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}
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static inline bool enic_poll_lock_poll(struct vnic_rq *rq)
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{
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bool rc = true;
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int rc = atomic_cmpxchg(&rq->bpoll_state, ENIC_POLL_STATE_IDLE,
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ENIC_POLL_STATE_POLL);
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spin_lock_bh(&rq->bpoll_lock);
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if (rq->bpoll_state & ENIC_POLL_LOCKED) {
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rq->bpoll_state |= ENIC_POLL_STATE_POLL_YIELD;
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rc = false;
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} else {
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rq->bpoll_state |= ENIC_POLL_STATE_POLL;
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}
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spin_unlock_bh(&rq->bpoll_lock);
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return rc;
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return (rc == ENIC_POLL_STATE_IDLE);
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}
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static inline bool enic_poll_unlock_poll(struct vnic_rq *rq)
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static inline void enic_poll_unlock_poll(struct vnic_rq *rq)
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{
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bool rc = false;
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spin_lock_bh(&rq->bpoll_lock);
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WARN_ON(rq->bpoll_state & ENIC_POLL_STATE_NAPI);
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if (rq->bpoll_state & ENIC_POLL_STATE_POLL_YIELD)
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rc = true;
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rq->bpoll_state = ENIC_POLL_STATE_IDLE;
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spin_unlock_bh(&rq->bpoll_lock);
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return rc;
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WARN_ON(atomic_read(&rq->bpoll_state) != ENIC_POLL_STATE_POLL);
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atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE);
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}
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static inline bool enic_poll_busy_polling(struct vnic_rq *rq)
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{
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WARN_ON(!(rq->bpoll_state & ENIC_POLL_LOCKED));
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return rq->bpoll_state & ENIC_POLL_USER_PEND;
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return atomic_read(&rq->bpoll_state) & ENIC_POLL_STATE_POLL;
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}
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#else
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@ -298,7 +260,8 @@ static inline bool enic_poll_lock_napi(struct vnic_rq *rq)
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return true;
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}
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static inline bool enic_poll_unlock_napi(struct vnic_rq *rq)
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static inline bool enic_poll_unlock_napi(struct vnic_rq *rq,
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struct napi_struct *napi)
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{
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return false;
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}
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