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Fixed race conditions on RDMA channel manipulations found via source reading:

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- Added a second argument to srpt_find_channel() that specified whether or not
  the channel should be removed from the channel list if found.
- Moved list_del() statement from the body of the srpt_release_channel()
  function to its callers.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@1005 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2009-08-03 16:00:36 +00:00
parent 7234de012f
commit 70110ec078
1 changed files with 28 additions and 19 deletions
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47
srpt/src/ib_srpt.c
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@@ -1337,7 +1337,7 @@ out:
*
* Return NULL if no matching RDMA channel has been found.
*/
static struct srpt_rdma_ch *srpt_find_channel(struct ib_cm_id *cm_id)
static struct srpt_rdma_ch *srpt_find_channel(struct ib_cm_id *cm_id, bool del)
{
struct srpt_device *sdev = cm_id->context;
struct srpt_rdma_ch *ch;
@@ -1345,6 +1345,8 @@ static struct srpt_rdma_ch *srpt_find_channel(struct ib_cm_id *cm_id)
spin_lock_irq(&sdev->spinlock);
list_for_each_entry(ch, &sdev->rch_list, list) {
if (ch->cm_id == cm_id) {
if (del)
list_del(&ch->list);
spin_unlock_irq(&sdev->spinlock);
return ch;
}
@@ -1355,19 +1357,17 @@ static struct srpt_rdma_ch *srpt_find_channel(struct ib_cm_id *cm_id)
return NULL;
}
/** Release all resources associated with the specified RDMA channel. */
/**
* Release all resources associated with the specified RDMA channel.
*
* Note: the caller must have removed the channel from the channel list
* before calling this function.
*/
static void srpt_release_channel(struct srpt_rdma_ch *ch, int destroy_cmid)
{
TRACE_ENTRY();
/*
* Remove the channel from the channel list such that
* srpt_find_channel() won't find this channel anymore and hence
* new incoming requests for this channel will be refused.
*/
spin_lock_irq(&ch->sport->sdev->spinlock);
list_del(&ch->list);
spin_unlock_irq(&ch->sport->sdev->spinlock);
WARN_ON(srpt_find_channel(ch->cm_id, false) == ch);
if (ch->cm_id && destroy_cmid) {
TRACE_DBG("%s: destroy cm_id= %p", __func__, ch->cm_id);
@@ -1482,6 +1482,9 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
" cm_id= %p state= %d",
ch->sess_name, ch->cm_id, ch->state);
if (ch->state == RDMA_CHANNEL_CONNECTING)
list_del(&ch->list);
spin_unlock_irq(&sdev->spinlock);
rsp->rsp_flags =
@@ -1563,10 +1566,6 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
goto destroy_ib;
}
spin_lock_irq(&sdev->spinlock);
list_add_tail(&ch->list, &sdev->rch_list);
spin_unlock_irq(&sdev->spinlock);
TRACE_DBG("Establish connection sess=%p name=%s cm_id=%p",
ch->scst_sess, ch->sess_name, ch->cm_id);
@@ -1594,7 +1593,11 @@ 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)
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);
goto out;
@@ -1633,7 +1636,7 @@ static void srpt_find_and_release_channel(struct ib_cm_id *cm_id)
{
struct srpt_rdma_ch *ch;
ch = srpt_find_channel(cm_id);
ch = srpt_find_channel(cm_id, true);
if (ch)
srpt_release_channel(ch, 0);
}
@@ -1649,7 +1652,7 @@ static int srpt_cm_rtu_recv(struct ib_cm_id *cm_id)
struct srpt_rdma_ch *ch;
int ret;
ch = srpt_find_channel(cm_id);
ch = srpt_find_channel(cm_id, false);
if (!ch)
return -EINVAL;
@@ -1696,7 +1699,7 @@ static int srpt_cm_dreq_recv(struct ib_cm_id *cm_id)
{
struct srpt_rdma_ch *ch;
ch = srpt_find_channel(cm_id);
ch = srpt_find_channel(cm_id, false);
if (!ch)
return -EINVAL;
@@ -2257,8 +2260,14 @@ static int srpt_release(struct scst_tgt *scst_tgt)
srpt_unregister_procfs_entry(scst_tgt->tgtt);
list_for_each_entry_safe(ch, tmp_ch, &sdev->rch_list, list)
spin_lock_irq(&sdev->spinlock);
list_for_each_entry_safe(ch, tmp_ch, &sdev->rch_list, list) {
list_del(&ch->list);
spin_unlock_irq(&sdev->spinlock);
srpt_release_channel(ch, 1);
spin_lock_irq(&sdev->spinlock);
}
spin_unlock_irq(&sdev->spinlock);
srpt_unregister_mad_agent(sdev);