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nvmf/vfio_user: move cq_is_full() closer to caller

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Move cq_is_full() closer to its caller post_completion() and along with
fixing comments.

Signed-off-by: Swapnil Ingle <swapnil.ingle@nutanix.com>
Change-Id: I93262d1805f0f9f075c6946ed97cd3006ffba130
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16415
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Community-CI: Mellanox Build Bot
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
This commit is contained in:
Swapnil Ingle 2023-01-23 15:01:54 +01:00 committed by Ben Walker
parent edfd7ff2d0
commit 94e395631e
1 changed files with 48 additions and 47 deletions
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95
lib/nvmf/vfio_user.c
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@ -605,53 +605,6 @@ cq_tail_advance(struct nvmf_vfio_user_cq *cq)
}
}
static uint32_t
cq_free_slots(struct nvmf_vfio_user_cq *cq)
{
uint32_t free_slots;
assert(cq != NULL);
if (cq->tail == cq->last_head) {
free_slots = cq->size;
} else if (cq->tail > cq->last_head) {
free_slots = cq->size - (cq->tail - cq->last_head);
} else {
free_slots = cq->last_head - cq->tail;
}
assert(free_slots > 0);
return free_slots - 1;
}
/*
* As per NVMe Base spec 3.3.1.2.1, we are supposed to implement CQ flow
* control: if there is no space in the CQ, we should wait until there is.
*
* In practice, we just fail the controller instead: as it happens, all host
* implementations we care about right-size the CQ: this is required anyway for
* NVMEoF support (see 3.3.2.8).
*
* Since reading the head doorbell is relatively expensive, we use the cached
* value, so we only have to read it for real if it appears that we are full.
*/
static inline bool
cq_is_full(struct nvmf_vfio_user_cq *cq)
{
uint32_t free_cq_slots;
assert(cq != NULL);
free_cq_slots = cq_free_slots(cq);
if (spdk_unlikely(free_cq_slots == 0)) {
cq->last_head = *cq_dbl_headp(cq);
free_cq_slots = cq_free_slots(cq);
}
return free_cq_slots == 0;
}
static bool
io_q_exists(struct nvmf_vfio_user_ctrlr *vu_ctrlr, const uint16_t qid, const bool is_cq)
{
@ -1724,6 +1677,46 @@ vfio_user_map_cmd(struct nvmf_vfio_user_ctrlr *ctrlr, struct spdk_nvmf_request *
static int handle_cmd_req(struct nvmf_vfio_user_ctrlr *ctrlr, struct spdk_nvme_cmd *cmd,
struct nvmf_vfio_user_sq *sq);
static uint32_t
cq_free_slots(struct nvmf_vfio_user_cq *cq)
{
uint32_t free_slots;
assert(cq != NULL);
if (cq->tail == cq->last_head) {
free_slots = cq->size;
} else if (cq->tail > cq->last_head) {
free_slots = cq->size - (cq->tail - cq->last_head);
} else {
free_slots = cq->last_head - cq->tail;
}
assert(free_slots > 0);
return free_slots - 1;
}
/*
* Since reading the head doorbell is relatively expensive, we use the cached
* value, so we only have to read it for real if it appears that we are full.
*/
static inline bool
cq_is_full(struct nvmf_vfio_user_cq *cq)
{
uint32_t free_cq_slots;
assert(cq != NULL);
free_cq_slots = cq_free_slots(cq);
if (spdk_unlikely(free_cq_slots == 0)) {
cq->last_head = *cq_dbl_headp(cq);
free_cq_slots = cq_free_slots(cq);
}
return free_cq_slots == 0;
}
/*
* Posts a CQE in the completion queue.
*
@ -1753,6 +1746,14 @@ post_completion(struct nvmf_vfio_user_ctrlr *ctrlr, struct nvmf_vfio_user_cq *cq
assert(spdk_get_thread() == cq->group->group->thread);
}
/*
* As per NVMe Base spec 3.3.1.2.1, we are supposed to implement CQ flow
* control: if there is no space in the CQ, we should wait until there is.
*
* In practice, we just fail the controller instead: as it happens, all host
* implementations we care about right-size the CQ: this is required anyway for
* NVMEoF support (see 3.3.2.8).
*/
if (cq_is_full(cq)) {
SPDK_ERRLOG("%s: cqid:%d full (tail=%d, head=%d)\n",
ctrlr_id(ctrlr), cq->qid, *cq_tailp(cq),