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- Fixed race conditions related to channel state manipulation.

Browse Source 
- Inlined srpt_disconnect_channel().
- Modified error handling coding style in srpt_cm_req_recv() to the usual
  kernel coding style: upon error, jump to the error handling code.
- Added more comments.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@1014 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2009-08-05 19:48:16 +00:00
parent 0e1890f3c7
commit 8ca3e36e99
1 changed files with 95 additions and 44 deletions
Download Patch File Download Diff File Expand all files Collapse all files

139
srpt/src/ib_srpt.c
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@@ -102,7 +102,6 @@ MODULE_PARM_DESC(thread,
static void srpt_add_one(struct ib_device *device);
static void srpt_remove_one(struct ib_device *device);
static void srpt_disconnect_channel(struct srpt_rdma_ch *ch, int dreq);
static void srpt_unregister_mad_agent(struct srpt_device *sdev);
static void srpt_unregister_procfs_entry(struct scst_tgt_template *tgt);
@@ -112,6 +111,32 @@ static struct ib_client srpt_client = {
.remove = srpt_remove_one
};
/**
* Atomically test and set the channel state.
* @ch: RDMA channel.
* @old: channel state to compare with.
* @new: state to change the channel state to if the current state matches the
* argument 'old'.
*
* Returns true if the channel state matched old upon entry of this function,
* and false otherwise.
*/
static bool srpt_test_and_set_channel_state(struct srpt_rdma_ch *ch,
enum rdma_ch_state old,
enum rdma_ch_state new)
{
unsigned long flags;
enum rdma_ch_state cur;
spin_lock_irqsave(&ch->spinlock, flags);
cur = ch->state;
if (cur == old)
ch->state = new;
spin_unlock_irqrestore(&ch->spinlock, flags);
return (cur == old);
}
/*
* Callback function called by the InfiniBand core when an asynchronous IB
* event occurs. This callback may occur in interrupt context. See also
@@ -193,9 +218,10 @@ static void srpt_qp_event(struct ib_event *event, void *ctx)
#endif
break;
case IB_EVENT_QP_LAST_WQE_REACHED:
if (ch->state == RDMA_CHANNEL_LIVE) {
TRACE_DBG("%s", "Schedule CM_DISCONNECT_WORK");
srpt_disconnect_channel(ch, 1);
if (srpt_test_and_set_channel_state(ch, RDMA_CHANNEL_LIVE,
RDMA_CHANNEL_DISCONNECTING)) {
TRACE_DBG("%s", "Disconnecting channel.");
ib_send_cm_dreq(ch->cm_id, NULL, 0);
}
break;
default:
@@ -757,6 +783,15 @@ static int srpt_init_ch_qp(struct srpt_rdma_ch *ch, struct ib_qp *qp)
return ret;
}
/**
* Change the state of a channel to 'ready to receive' or 'ready to send'.
* @ch: channel of the queue pair.
* @qp: queue pair whose attributes should be modified.
* @qp_state: new state of the queue pair; either IB_QPS_RTS or IB_QPS_RTR
* (RTS = ready to send; RTR = ready to receive).
*
* Returns zero upon success and a negative value upon failure.
*/
static int srpt_ch_qp_rtr_rts(struct srpt_rdma_ch *ch, struct ib_qp *qp,
enum ib_qp_state qp_state)
{
@@ -1171,16 +1206,19 @@ static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
unsigned long flags;
int len;
spin_lock_irqsave(&ch->spinlock, flags);
if (ch->state != RDMA_CHANNEL_LIVE) {
if (ch->state == RDMA_CHANNEL_CONNECTING) {
spin_lock_irqsave(&ch->spinlock, flags);
list_add_tail(&ioctx->wait_list, &ch->cmd_wait_list);
spin_unlock_irqrestore(&ch->spinlock, flags);
} else
return;
} else {
spin_unlock_irqrestore(&ch->spinlock, flags);
srpt_reset_ioctx(ch, ioctx);
return;
return;
}
}
spin_unlock_irqrestore(&ch->spinlock, flags);
dma_sync_single_for_cpu(ch->sport->sdev->device->dma_device, ioctx->dma,
MAX_MESSAGE_SIZE, DMA_FROM_DEVICE);
@@ -1215,6 +1253,8 @@ static void srpt_handle_new_iu(struct srpt_rdma_ch *ch,
goto err;
}
WARN_ON(srp_rsp->opcode == SRP_RSP);
dma_sync_single_for_device(ch->sport->sdev->device->dma_device,
ioctx->dma, MAX_MESSAGE_SIZE,
DMA_FROM_DEVICE);
@@ -1225,7 +1265,12 @@ err:
WARN_ON(srp_rsp->opcode != SRP_RSP);
len = (sizeof *srp_rsp) + be32_to_cpu(srp_rsp->sense_data_len);
if (ch->state != RDMA_CHANNEL_LIVE || srpt_post_send(ch, ioctx, len)) {
if (ch->state != RDMA_CHANNEL_LIVE) {
/* Give up if another thread modified the channel state. */
printk(KERN_ERR PFX "%s: channel is in state %d",
__func__, ch->state);
srpt_reset_ioctx(ch, ioctx);
} else if (srpt_post_send(ch, ioctx, len)) {
printk(KERN_ERR PFX "%s: sending SRP_RSP PDU failed",
__func__);
srpt_reset_ioctx(ch, ioctx);
@@ -1464,18 +1509,6 @@ static void srpt_release_channel(struct srpt_rdma_ch *ch, int destroy_cmid)
TRACE_EXIT();
}
static void srpt_disconnect_channel(struct srpt_rdma_ch *ch, int dreq)
{
spin_lock_irq(&ch->spinlock);
ch->state = RDMA_CHANNEL_DISCONNECTING;
spin_unlock_irq(&ch->spinlock);
if (dreq)
ib_send_cm_dreq(ch->cm_id, NULL, 0);
else
ib_send_cm_drep(ch->cm_id, NULL, 0);
}
static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
struct ib_cm_req_event_param *param,
void *private_data)
@@ -1532,12 +1565,17 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
&& param->port == ch->sport->port
&& param->listen_id == ch->sport->sdev->cm_id
&& ch->cm_id) {
enum rdma_ch_state prev_state;
/* found an existing channel */
TRACE_DBG("Found existing channel name= %s"
" cm_id= %p state= %d",
ch->sess_name, ch->cm_id, ch->state);
if (ch->state == RDMA_CHANNEL_CONNECTING)
prev_state = ch->state;
if (ch->state == RDMA_CHANNEL_LIVE)
ch->state = RDMA_CHANNEL_DISCONNECTING;
else if (ch->state == RDMA_CHANNEL_CONNECTING)
list_del(&ch->list);
spin_unlock_irq(&sdev->spinlock);
@@ -1545,9 +1583,10 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
rsp->rsp_flags =
SRP_LOGIN_RSP_MULTICHAN_TERMINATED;
if (ch->state == RDMA_CHANNEL_LIVE)
srpt_disconnect_channel(ch, 1);
else if (ch->state == RDMA_CHANNEL_CONNECTING) {
if (prev_state == RDMA_CHANNEL_LIVE)
ib_send_cm_dreq(ch->cm_id, NULL, 0);
else if (prev_state ==
RDMA_CHANNEL_CONNECTING) {
ib_send_cm_rej(ch->cm_id,
IB_CM_REJ_NO_RESOURCES,
NULL, 0, NULL, 0);
@@ -1648,15 +1687,19 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
rep_param->initiator_depth = 4;
ret = ib_send_cm_rep(cm_id, rep_param);
if (ret == 0) {
spin_lock_irq(&sdev->spinlock);
list_add_tail(&ch->list, &sdev->rch_list);
spin_unlock_irq(&sdev->spinlock);
} else
srpt_release_channel(ch, 0);
if (ret)
goto release_channel;
spin_lock_irq(&sdev->spinlock);
list_add_tail(&ch->list, &sdev->rch_list);
spin_unlock_irq(&sdev->spinlock);
goto out;
release_channel:
scst_unregister_session(ch->scst_sess, 0, NULL);
ch->scst_sess = NULL;
destroy_ib:
ib_destroy_qp(ch->qp);
ib_destroy_cq(ch->cq);
@@ -1702,6 +1745,12 @@ static void srpt_cm_rej_recv(struct ib_cm_id *cm_id)
srpt_find_and_release_channel(cm_id);
}
/**
* Process an IB_CM_RTU_RECEIVED or IB_CM_USER_ESTABLISHED event.
*
* An IB_CM_RTU_RECEIVED message indicates that the connection is established
* and that the recipient may begin transmitting (RTU = ready to use).
*/
static int srpt_cm_rtu_recv(struct ib_cm_id *cm_id)
{
struct srpt_rdma_ch *ch;
@@ -1711,12 +1760,10 @@ static int srpt_cm_rtu_recv(struct ib_cm_id *cm_id)
if (!ch)
return -EINVAL;
if (ch->state == RDMA_CHANNEL_CONNECTING) {
if (srpt_test_and_set_channel_state(ch, RDMA_CHANNEL_CONNECTING,
RDMA_CHANNEL_LIVE)) {
struct srpt_ioctx *ioctx, *ioctx_tmp;
spin_lock_irq(&ch->spinlock);
ch->state = RDMA_CHANNEL_LIVE;
spin_unlock_irq(&ch->spinlock);
ret = srpt_ch_qp_rtr_rts(ch, ch->qp, IB_QPS_RTS);
list_for_each_entry_safe(ioctx, ioctx_tmp, &ch->cmd_wait_list,
@@ -1724,16 +1771,20 @@ static int srpt_cm_rtu_recv(struct ib_cm_id *cm_id)
list_del(&ioctx->wait_list);
srpt_handle_new_iu(ch, ioctx);
}
} else if (ch->state == RDMA_CHANNEL_DISCONNECTING)
ret = -EAGAIN;
else
ret = 0;
if (ret) {
if (ret && srpt_test_and_set_channel_state(ch,
RDMA_CHANNEL_LIVE,
RDMA_CHANNEL_DISCONNECTING)) {
TRACE_DBG("cm_id=%p sess_name=%s state=%d",
cm_id, ch->sess_name, ch->state);
ib_send_cm_dreq(ch->cm_id, NULL, 0);
}
} else if (ch->state == RDMA_CHANNEL_DISCONNECTING) {
TRACE_DBG("cm_id=%p sess_name=%s state=%d",
cm_id, ch->sess_name, ch->state);
srpt_disconnect_channel(ch, 1);
}
ib_send_cm_dreq(ch->cm_id, NULL, 0);
ret = -EAGAIN;
} else
ret = 0;
return ret;
}
@@ -1764,7 +1815,7 @@ static int srpt_cm_dreq_recv(struct ib_cm_id *cm_id)
switch (ch->state) {
case RDMA_CHANNEL_LIVE:
case RDMA_CHANNEL_CONNECTING:
srpt_disconnect_channel(ch, 0);
ib_send_cm_drep(ch->cm_id, NULL, 0);
break;
case RDMA_CHANNEL_DISCONNECTING:
default: