From 8aac4cc3a9d7d7c2f203b7a8db521b604cfb5dc9 Mon Sep 17 00:00:00 2001 From: Mike Marciniszyn Date: Wed, 27 Jun 2012 18:33:19 -0400 Subject: [PATCH] IB/qib: RCU locking for MR validation Profiling indicates that MR validation locking is expensive. The MR table is largely read-only and is a suitable candidate for RCU locking. The patch uses RCU locking during validation to eliminate one lock/unlock during that validation. Reviewed-by: Mike Heinz Signed-off-by: Mike Marciniszyn Signed-off-by: Roland Dreier --- drivers/infiniband/hw/qib/qib_keys.c | 98 ++++++++++++++------------- drivers/infiniband/hw/qib/qib_mr.c | 7 ++ drivers/infiniband/hw/qib/qib_verbs.c | 4 +- drivers/infiniband/hw/qib/qib_verbs.h | 7 +- 4 files changed, 66 insertions(+), 50 deletions(-) diff --git a/drivers/infiniband/hw/qib/qib_keys.c b/drivers/infiniband/hw/qib/qib_keys.c index 8b5ee3aa8e3d..970165b027f7 100644 --- a/drivers/infiniband/hw/qib/qib_keys.c +++ b/drivers/infiniband/hw/qib/qib_keys.c @@ -40,8 +40,7 @@ * * Returns 0 if successful, otherwise returns -errno. * - * Increments mr reference count and sets published - * as required. + * Increments mr reference count as required. * * Sets the lkey field mr for non-dma regions. * @@ -60,10 +59,12 @@ int qib_alloc_lkey(struct qib_mregion *mr, int dma_region) /* special case for dma_mr lkey == 0 */ if (dma_region) { - /* should the dma_mr be relative to the pd? */ - if (!dev->dma_mr) { + struct qib_mregion *tmr; + + tmr = rcu_dereference(dev->dma_mr); + if (!tmr) { qib_get_mr(mr); - dev->dma_mr = mr; + rcu_assign_pointer(dev->dma_mr, mr); mr->lkey_published = 1; } goto success; @@ -93,7 +94,7 @@ int qib_alloc_lkey(struct qib_mregion *mr, int dma_region) rkt->gen++; } qib_get_mr(mr); - rkt->table[r] = mr; + rcu_assign_pointer(rkt->table[r], mr); mr->lkey_published = 1; success: spin_unlock_irqrestore(&rkt->lock, flags); @@ -120,33 +121,30 @@ void qib_free_lkey(struct qib_mregion *mr) spin_lock_irqsave(&rkt->lock, flags); if (!mr->lkey_published) goto out; - mr->lkey_published = 0; - - - spin_lock_irqsave(&dev->lk_table.lock, flags); - if (lkey == 0) { - if (dev->dma_mr && dev->dma_mr == mr) { - qib_put_mr(dev->dma_mr); - dev->dma_mr = NULL; - } - } else { + if (lkey == 0) + rcu_assign_pointer(dev->dma_mr, NULL); + else { r = lkey >> (32 - ib_qib_lkey_table_size); - qib_put_mr(dev->dma_mr); - rkt->table[r] = NULL; + rcu_assign_pointer(rkt->table[r], NULL); } + qib_put_mr(mr); + mr->lkey_published = 0; out: - spin_unlock_irqrestore(&dev->lk_table.lock, flags); + spin_unlock_irqrestore(&rkt->lock, flags); } /** * qib_lkey_ok - check IB SGE for validity and initialize * @rkt: table containing lkey to check SGE against + * @pd: protection domain * @isge: outgoing internal SGE * @sge: SGE to check * @acc: access flags * * Return 1 if valid and successful, otherwise returns 0. * + * increments the reference count upon success + * * Check the IB SGE for validity and initialize our internal version * of it. */ @@ -156,24 +154,25 @@ int qib_lkey_ok(struct qib_lkey_table *rkt, struct qib_pd *pd, struct qib_mregion *mr; unsigned n, m; size_t off; - unsigned long flags; /* * We use LKEY == zero for kernel virtual addresses * (see qib_get_dma_mr and qib_dma.c). */ - spin_lock_irqsave(&rkt->lock, flags); + rcu_read_lock(); if (sge->lkey == 0) { struct qib_ibdev *dev = to_idev(pd->ibpd.device); if (pd->user) goto bail; - if (!dev->dma_mr) + mr = rcu_dereference(dev->dma_mr); + if (!mr) + goto bail; + if (unlikely(!atomic_inc_not_zero(&mr->refcount))) goto bail; - qib_get_mr(dev->dma_mr); - spin_unlock_irqrestore(&rkt->lock, flags); + rcu_read_unlock(); - isge->mr = dev->dma_mr; + isge->mr = mr; isge->vaddr = (void *) sge->addr; isge->length = sge->length; isge->sge_length = sge->length; @@ -181,18 +180,18 @@ int qib_lkey_ok(struct qib_lkey_table *rkt, struct qib_pd *pd, isge->n = 0; goto ok; } - mr = rkt->table[(sge->lkey >> (32 - ib_qib_lkey_table_size))]; - if (unlikely(mr == NULL || mr->lkey != sge->lkey || - mr->pd != &pd->ibpd)) + mr = rcu_dereference( + rkt->table[(sge->lkey >> (32 - ib_qib_lkey_table_size))]); + if (unlikely(!mr || mr->lkey != sge->lkey || mr->pd != &pd->ibpd)) goto bail; off = sge->addr - mr->user_base; - if (unlikely(sge->addr < mr->user_base || - off + sge->length > mr->length || - (mr->access_flags & acc) != acc)) + if (unlikely(sge->addr < mr->iova || off + sge->length > mr->length || + (mr->access_flags & acc) == 0)) goto bail; - qib_get_mr(mr); - spin_unlock_irqrestore(&rkt->lock, flags); + if (unlikely(!atomic_inc_not_zero(&mr->refcount))) + goto bail; + rcu_read_unlock(); off += mr->offset; if (mr->page_shift) { @@ -228,20 +227,22 @@ int qib_lkey_ok(struct qib_lkey_table *rkt, struct qib_pd *pd, ok: return 1; bail: - spin_unlock_irqrestore(&rkt->lock, flags); + rcu_read_unlock(); return 0; } /** * qib_rkey_ok - check the IB virtual address, length, and RKEY - * @dev: infiniband device - * @ss: SGE state + * @qp: qp for validation + * @sge: SGE state * @len: length of data * @vaddr: virtual address to place data * @rkey: rkey to check * @acc: access flags * * Return 1 if successful, otherwise 0. + * + * increments the reference count upon success */ int qib_rkey_ok(struct qib_qp *qp, struct qib_sge *sge, u32 len, u64 vaddr, u32 rkey, int acc) @@ -250,25 +251,26 @@ int qib_rkey_ok(struct qib_qp *qp, struct qib_sge *sge, struct qib_mregion *mr; unsigned n, m; size_t off; - unsigned long flags; /* * We use RKEY == zero for kernel virtual addresses * (see qib_get_dma_mr and qib_dma.c). */ - spin_lock_irqsave(&rkt->lock, flags); + rcu_read_lock(); if (rkey == 0) { struct qib_pd *pd = to_ipd(qp->ibqp.pd); struct qib_ibdev *dev = to_idev(pd->ibpd.device); if (pd->user) goto bail; - if (!dev->dma_mr) + mr = rcu_dereference(dev->dma_mr); + if (!mr) goto bail; - qib_get_mr(dev->dma_mr); - spin_unlock_irqrestore(&rkt->lock, flags); + if (unlikely(!atomic_inc_not_zero(&mr->refcount))) + goto bail; + rcu_read_unlock(); - sge->mr = dev->dma_mr; + sge->mr = mr; sge->vaddr = (void *) vaddr; sge->length = len; sge->sge_length = len; @@ -277,16 +279,18 @@ int qib_rkey_ok(struct qib_qp *qp, struct qib_sge *sge, goto ok; } - mr = rkt->table[(rkey >> (32 - ib_qib_lkey_table_size))]; - if (unlikely(mr == NULL || mr->lkey != rkey || qp->ibqp.pd != mr->pd)) + mr = rcu_dereference( + rkt->table[(rkey >> (32 - ib_qib_lkey_table_size))]); + if (unlikely(!mr || mr->lkey != rkey || qp->ibqp.pd != mr->pd)) goto bail; off = vaddr - mr->iova; if (unlikely(vaddr < mr->iova || off + len > mr->length || (mr->access_flags & acc) == 0)) goto bail; - qib_get_mr(mr); - spin_unlock_irqrestore(&rkt->lock, flags); + if (unlikely(!atomic_inc_not_zero(&mr->refcount))) + goto bail; + rcu_read_unlock(); off += mr->offset; if (mr->page_shift) { @@ -322,7 +326,7 @@ int qib_rkey_ok(struct qib_qp *qp, struct qib_sge *sge, ok: return 1; bail: - spin_unlock_irqrestore(&rkt->lock, flags); + rcu_read_unlock(); return 0; } diff --git a/drivers/infiniband/hw/qib/qib_mr.c b/drivers/infiniband/hw/qib/qib_mr.c index 6a2028a56e3d..e6687ded8210 100644 --- a/drivers/infiniband/hw/qib/qib_mr.c +++ b/drivers/infiniband/hw/qib/qib_mr.c @@ -527,3 +527,10 @@ int qib_dealloc_fmr(struct ib_fmr *ibfmr) out: return ret; } + +void mr_rcu_callback(struct rcu_head *list) +{ + struct qib_mregion *mr = container_of(list, struct qib_mregion, list); + + complete(&mr->comp); +} diff --git a/drivers/infiniband/hw/qib/qib_verbs.c b/drivers/infiniband/hw/qib/qib_verbs.c index 76d7ce8a8c6e..59cdea345a82 100644 --- a/drivers/infiniband/hw/qib/qib_verbs.c +++ b/drivers/infiniband/hw/qib/qib_verbs.c @@ -2066,7 +2066,9 @@ int qib_register_ib_device(struct qib_devdata *dd) ret = -ENOMEM; goto err_lk; } - memset(dev->lk_table.table, 0, lk_tab_size); + RCU_INIT_POINTER(dev->dma_mr, NULL); + for (i = 0; i < dev->lk_table.max; i++) + RCU_INIT_POINTER(dev->lk_table.table[i], NULL); INIT_LIST_HEAD(&dev->pending_mmaps); spin_lock_init(&dev->pending_lock); dev->mmap_offset = PAGE_SIZE; diff --git a/drivers/infiniband/hw/qib/qib_verbs.h b/drivers/infiniband/hw/qib/qib_verbs.h index 4a2277bc059e..85751fd74371 100644 --- a/drivers/infiniband/hw/qib/qib_verbs.h +++ b/drivers/infiniband/hw/qib/qib_verbs.h @@ -303,8 +303,9 @@ struct qib_mregion { u32 max_segs; /* number of qib_segs in all the arrays */ u32 mapsz; /* size of the map array */ u8 page_shift; /* 0 - non unform/non powerof2 sizes */ - u8 lkey_published; /* in global table */ + u8 lkey_published; /* in global table */ struct completion comp; /* complete when refcount goes to zero */ + struct rcu_head list; atomic_t refcount; struct qib_segarray *map[0]; /* the segments */ }; @@ -1022,10 +1023,12 @@ static inline void qib_get_mr(struct qib_mregion *mr) atomic_inc(&mr->refcount); } +void mr_rcu_callback(struct rcu_head *list); + static inline void qib_put_mr(struct qib_mregion *mr) { if (unlikely(atomic_dec_and_test(&mr->refcount))) - complete(&mr->comp); + call_rcu(&mr->list, mr_rcu_callback); } static inline void qib_put_ss(struct qib_sge_state *ss) -- 2.20.1