From f586a3360197a63b5423001553ab23025242ac72 Mon Sep 17 00:00:00 2001 From: Govindarajulu Varadarajan <_govind@gmx.com> Date: Thu, 25 Jun 2015 16:02:04 +0530 Subject: [PATCH] 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 --- drivers/net/ethernet/cisco/enic/enic_main.c | 4 +- drivers/net/ethernet/cisco/enic/vnic_rq.h | 91 ++++++--------------- 2 files changed, 29 insertions(+), 66 deletions(-) diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c index eadae1b412c6..da2004e2a741 100644 --- a/drivers/net/ethernet/cisco/enic/enic_main.c +++ b/drivers/net/ethernet/cisco/enic/enic_main.c @@ -1208,7 +1208,7 @@ static int enic_poll(struct napi_struct *napi, int budget) napi_complete(napi); vnic_intr_unmask(&enic->intr[intr]); } - enic_poll_unlock_napi(&enic->rq[cq_rq]); + enic_poll_unlock_napi(&enic->rq[cq_rq], napi); return rq_work_done; } @@ -1414,7 +1414,7 @@ static int enic_poll_msix_rq(struct napi_struct *napi, int budget) */ enic_calc_int_moderation(enic, &enic->rq[rq]); - enic_poll_unlock_napi(&enic->rq[rq]); + enic_poll_unlock_napi(&enic->rq[rq], napi); if (work_done < work_to_do) { /* Some work done, but not enough to stay in polling, diff --git a/drivers/net/ethernet/cisco/enic/vnic_rq.h b/drivers/net/ethernet/cisco/enic/vnic_rq.h index 8111d5202df2..b9c82f143d7e 100644 --- a/drivers/net/ethernet/cisco/enic/vnic_rq.h +++ b/drivers/net/ethernet/cisco/enic/vnic_rq.h @@ -21,6 +21,7 @@ #define _VNIC_RQ_H_ #include +#include #include "vnic_dev.h" #include "vnic_cq.h" @@ -75,6 +76,12 @@ struct vnic_rq_buf { uint64_t wr_id; }; +enum enic_poll_state { + ENIC_POLL_STATE_IDLE, + ENIC_POLL_STATE_NAPI, + ENIC_POLL_STATE_POLL +}; + struct vnic_rq { unsigned int index; struct vnic_dev *vdev; @@ -86,19 +93,7 @@ struct vnic_rq { void *os_buf_head; unsigned int pkts_outstanding; #ifdef CONFIG_NET_RX_BUSY_POLL -#define ENIC_POLL_STATE_IDLE 0 -#define ENIC_POLL_STATE_NAPI (1 << 0) /* NAPI owns this poll */ -#define ENIC_POLL_STATE_POLL (1 << 1) /* poll owns this poll */ -#define ENIC_POLL_STATE_NAPI_YIELD (1 << 2) /* NAPI yielded this poll */ -#define ENIC_POLL_STATE_POLL_YIELD (1 << 3) /* poll yielded this poll */ -#define ENIC_POLL_YIELD (ENIC_POLL_STATE_NAPI_YIELD | \ - ENIC_POLL_STATE_POLL_YIELD) -#define ENIC_POLL_LOCKED (ENIC_POLL_STATE_NAPI | \ - ENIC_POLL_STATE_POLL) -#define ENIC_POLL_USER_PEND (ENIC_POLL_STATE_POLL | \ - ENIC_POLL_STATE_POLL_YIELD) - unsigned int bpoll_state; - spinlock_t bpoll_lock; + atomic_t bpoll_state; #endif /* CONFIG_NET_RX_BUSY_POLL */ }; @@ -215,76 +210,43 @@ static inline int vnic_rq_fill(struct vnic_rq *rq, #ifdef CONFIG_NET_RX_BUSY_POLL static inline void enic_busy_poll_init_lock(struct vnic_rq *rq) { - spin_lock_init(&rq->bpoll_lock); - rq->bpoll_state = ENIC_POLL_STATE_IDLE; + atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE); } static inline bool enic_poll_lock_napi(struct vnic_rq *rq) { - bool rc = true; - - spin_lock(&rq->bpoll_lock); - if (rq->bpoll_state & ENIC_POLL_LOCKED) { - WARN_ON(rq->bpoll_state & ENIC_POLL_STATE_NAPI); - rq->bpoll_state |= ENIC_POLL_STATE_NAPI_YIELD; - rc = false; - } else { - rq->bpoll_state = ENIC_POLL_STATE_NAPI; - } - spin_unlock(&rq->bpoll_lock); + int rc = atomic_cmpxchg(&rq->bpoll_state, ENIC_POLL_STATE_IDLE, + ENIC_POLL_STATE_NAPI); - return rc; + return (rc == ENIC_POLL_STATE_IDLE); } -static inline bool enic_poll_unlock_napi(struct vnic_rq *rq) +static inline void enic_poll_unlock_napi(struct vnic_rq *rq, + struct napi_struct *napi) { - bool rc = false; - - spin_lock(&rq->bpoll_lock); - WARN_ON(rq->bpoll_state & - (ENIC_POLL_STATE_POLL | ENIC_POLL_STATE_NAPI_YIELD)); - if (rq->bpoll_state & ENIC_POLL_STATE_POLL_YIELD) - rc = true; - rq->bpoll_state = ENIC_POLL_STATE_IDLE; - spin_unlock(&rq->bpoll_lock); - - return rc; + WARN_ON(atomic_read(&rq->bpoll_state) != ENIC_POLL_STATE_NAPI); + napi_gro_flush(napi, false); + atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE); } static inline bool enic_poll_lock_poll(struct vnic_rq *rq) { - bool rc = true; - - spin_lock_bh(&rq->bpoll_lock); - if (rq->bpoll_state & ENIC_POLL_LOCKED) { - rq->bpoll_state |= ENIC_POLL_STATE_POLL_YIELD; - rc = false; - } else { - rq->bpoll_state |= ENIC_POLL_STATE_POLL; - } - spin_unlock_bh(&rq->bpoll_lock); + int rc = atomic_cmpxchg(&rq->bpoll_state, ENIC_POLL_STATE_IDLE, + ENIC_POLL_STATE_POLL); - return rc; + return (rc == ENIC_POLL_STATE_IDLE); } -static inline bool enic_poll_unlock_poll(struct vnic_rq *rq) -{ - bool rc = false; - spin_lock_bh(&rq->bpoll_lock); - WARN_ON(rq->bpoll_state & ENIC_POLL_STATE_NAPI); - if (rq->bpoll_state & ENIC_POLL_STATE_POLL_YIELD) - rc = true; - rq->bpoll_state = ENIC_POLL_STATE_IDLE; - spin_unlock_bh(&rq->bpoll_lock); - - return rc; +static inline void enic_poll_unlock_poll(struct vnic_rq *rq) +{ + WARN_ON(atomic_read(&rq->bpoll_state) != ENIC_POLL_STATE_POLL); + atomic_set(&rq->bpoll_state, ENIC_POLL_STATE_IDLE); } static inline bool enic_poll_busy_polling(struct vnic_rq *rq) { - WARN_ON(!(rq->bpoll_state & ENIC_POLL_LOCKED)); - return rq->bpoll_state & ENIC_POLL_USER_PEND; + return atomic_read(&rq->bpoll_state) & ENIC_POLL_STATE_POLL; } #else @@ -298,7 +260,8 @@ static inline bool enic_poll_lock_napi(struct vnic_rq *rq) return true; } -static inline bool enic_poll_unlock_napi(struct vnic_rq *rq) +static inline bool enic_poll_unlock_napi(struct vnic_rq *rq, + struct napi_struct *napi) { return false; } -- 2.30.2