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IB/srpt: Don't allow reordering of commands on wait list
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If a receive I/O context is removed from the wait list and
srpt_handle_new_iu() fails to allocate a send I/O context then
re-adding the receive I/O context to the wait list can cause
reordering. Avoid this by only removing a receive I/O context
from the wait list after allocating a send I/O context succeeded.

Signed-off-by: Bart Van Assche <[email protected]>
Signed-off-by: Doug Ledford <[email protected]>
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@KAGA-KOKO @dledford
KAGA-KOKO authored and dledford committed Jan 18, 2018
1 parent e28a547 commit fcf5893
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Showing 2 changed files with 49 additions and 35 deletions.
82 changes: 47 additions & 35 deletions drivers/infiniband/ulp/srpt/ib_srpt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1533,39 +1533,39 @@ static void srpt_handle_tsk_mgmt(struct srpt_rdma_ch *ch,
* srpt_handle_new_iu - process a newly received information unit
* @ch: RDMA channel through which the information unit has been received.
* @recv_ioctx: Receive I/O context associated with the information unit.
* @send_ioctx: Send I/O context.
*/
static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
struct srpt_recv_ioctx *recv_ioctx,
struct srpt_send_ioctx *send_ioctx)
static bool
srpt_handle_new_iu(struct srpt_rdma_ch *ch, struct srpt_recv_ioctx *recv_ioctx)
{
struct srpt_send_ioctx *send_ioctx = NULL;
struct srp_cmd *srp_cmd;
bool res = false;
u8 opcode;

BUG_ON(!ch);
BUG_ON(!recv_ioctx);

if (unlikely(ch->state == CH_CONNECTING))
goto push;

ib_dma_sync_single_for_cpu(ch->sport->sdev->device,
recv_ioctx->ioctx.dma, srp_max_req_size,
DMA_FROM_DEVICE);

if (unlikely(ch->state == CH_CONNECTING))
goto out_wait;

if (unlikely(ch->state != CH_LIVE))
return;

srp_cmd = recv_ioctx->ioctx.buf;
if (srp_cmd->opcode == SRP_CMD || srp_cmd->opcode == SRP_TSK_MGMT) {
if (!send_ioctx) {
if (!list_empty(&ch->cmd_wait_list))
goto out_wait;
send_ioctx = srpt_get_send_ioctx(ch);
}
opcode = srp_cmd->opcode;
if (opcode == SRP_CMD || opcode == SRP_TSK_MGMT) {
send_ioctx = srpt_get_send_ioctx(ch);
if (unlikely(!send_ioctx))
goto out_wait;
goto push;
}

switch (srp_cmd->opcode) {
if (!list_empty(&recv_ioctx->wait_list)) {
WARN_ON_ONCE(!ch->processing_wait_list);
list_del_init(&recv_ioctx->wait_list);
}

switch (opcode) {
case SRP_CMD:
srpt_handle_cmd(ch, recv_ioctx, send_ioctx);
break;
Expand All @@ -1585,16 +1585,22 @@ static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
pr_err("Received SRP_RSP\n");
break;
default:
pr_err("received IU with unknown opcode 0x%x\n",
srp_cmd->opcode);
pr_err("received IU with unknown opcode 0x%x\n", opcode);
break;
}

srpt_post_recv(ch->sport->sdev, ch, recv_ioctx);
return;
res = true;

out_wait:
list_add_tail(&recv_ioctx->wait_list, &ch->cmd_wait_list);
out:
return res;

push:
if (list_empty(&recv_ioctx->wait_list)) {
WARN_ON_ONCE(ch->processing_wait_list);
list_add_tail(&recv_ioctx->wait_list, &ch->cmd_wait_list);
}
goto out;
}

static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
Expand All @@ -1609,7 +1615,7 @@ static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
req_lim = atomic_dec_return(&ch->req_lim);
if (unlikely(req_lim < 0))
pr_err("req_lim = %d < 0\n", req_lim);
srpt_handle_new_iu(ch, ioctx, NULL);
srpt_handle_new_iu(ch, ioctx);
} else {
pr_info_ratelimited("receiving failed for ioctx %p with status %d\n",
ioctx, wc->status);
Expand All @@ -1623,19 +1629,21 @@ static void srpt_recv_done(struct ib_cq *cq, struct ib_wc *wc)
*/
static void srpt_process_wait_list(struct srpt_rdma_ch *ch)
{
struct srpt_send_ioctx *ioctx;
struct srpt_recv_ioctx *recv_ioctx, *tmp;

while (!list_empty(&ch->cmd_wait_list) &&
ch->state >= CH_LIVE &&
(ioctx = srpt_get_send_ioctx(ch)) != NULL) {
struct srpt_recv_ioctx *recv_ioctx;
WARN_ON_ONCE(ch->state == CH_CONNECTING);

recv_ioctx = list_first_entry(&ch->cmd_wait_list,
struct srpt_recv_ioctx,
wait_list);
list_del(&recv_ioctx->wait_list);
srpt_handle_new_iu(ch, recv_ioctx, ioctx);
if (list_empty(&ch->cmd_wait_list))
return;

WARN_ON_ONCE(ch->processing_wait_list);
ch->processing_wait_list = true;
list_for_each_entry_safe(recv_ioctx, tmp, &ch->cmd_wait_list,
wait_list) {
if (!srpt_handle_new_iu(ch, recv_ioctx))
break;
}
ch->processing_wait_list = false;
}

/**
Expand Down Expand Up @@ -2150,6 +2158,8 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
cpu_to_be32(SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
goto free_ring;
}
for (i = 0; i < ch->rq_size; i++)
INIT_LIST_HEAD(&ch->ioctx_recv_ring[i]->wait_list);
}

ret = srpt_create_ch_ib(ch);
Expand Down Expand Up @@ -2773,8 +2783,10 @@ static int srpt_alloc_srq(struct srpt_device *sdev)
sdev->use_srq = true;
sdev->srq = srq;

for (i = 0; i < sdev->srq_size; ++i)
for (i = 0; i < sdev->srq_size; ++i) {
INIT_LIST_HEAD(&sdev->ioctx_ring[i]->wait_list);
srpt_post_recv(sdev, NULL, sdev->ioctx_ring[i]);
}

return 0;
}
Expand Down
2 changes: 2 additions & 0 deletions drivers/infiniband/ulp/srpt/ib_srpt.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -261,6 +261,7 @@ enum rdma_ch_state {
* @spinlock: Protects free_list and state.
* @free_list: Head of list with free send I/O contexts.
* @state: channel state. See also enum rdma_ch_state.
* @processing_wait_list: Whether or not cmd_wait_list is being processed.
* @ioctx_ring: Send ring.
* @ioctx_recv_ring: Receive I/O context ring.
* @list: Node in srpt_nexus.ch_list.
Expand Down Expand Up @@ -295,6 +296,7 @@ struct srpt_rdma_ch {
struct list_head list;
struct list_head cmd_wait_list;
uint16_t pkey;
bool processing_wait_list;
struct se_session *sess;
u8 sess_name[24];
struct work_struct release_work;
Expand Down

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