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Fixed the following race conditions:

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- With thread=1, the kernel thread was stopped before all I/O was stopped.
  This could result in IB completions for responses sent to the initiator
  not being processed, scst_tgt_cmd_done() not being called for certain
  SCST commands and hence this race could cause "rmmod ib_srpt" to hang.
- ib_unregister_event_handler() was called after cancel_work_sync(). This
  could cause srpt_event_handler() to queue new work, work that could be
  executed after the data it operates on had been deallocated.
Change: simplified module unloading by calling ib_destroy_cm_id(sdev->cm_id)
  before calling scst_unregister(). This made the variable "cleaning_up"
  superfluous.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@1441 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2010-01-09 20:14:13 +00:00
parent 1660fe1c3c
commit 5cc522712e
1 changed files with 19 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

42
srpt/src/ib_srpt.c
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@@ -95,7 +95,6 @@ static int use_port_guid_in_session_name;
static int thread = 1;
static struct srpt_thread srpt_thread;
static DECLARE_WAIT_QUEUE_HEAD(ioctx_list_waitQ);
static atomic_t cleaning_up;
#if defined(CONFIG_SCST_DEBUG) || defined(CONFIG_SCST_TRACING)
static unsigned long trace_flag = DEFAULT_SRPT_TRACE_FLAGS;
module_param(trace_flag, long, 0644);
@@ -2055,12 +2054,6 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
goto out;
}
if (atomic_read(&cleaning_up)) {
PRINT_INFO("%s", "rejected SRP_LOGIN_REQ because ib_srpt is"
" being removed");
goto reject;
}
if (it_iu_len > srp_max_message_size || it_iu_len < 64) {
rej->reason =
cpu_to_be32(SRP_LOGIN_REJ_REQ_IT_IU_LENGTH_TOO_LARGE);
@@ -2968,8 +2961,6 @@ static int srpt_release(struct scst_tgt *scst_tgt)
}
spin_unlock_irq(&sdev->spinlock);
srpt_unregister_mad_agent(sdev);
scst_tgt_set_tgt_priv(scst_tgt, NULL);
TRACE_EXIT();
@@ -3366,36 +3357,42 @@ static void srpt_remove_one(struct ib_device *device)
return;
#endif
/*
* Cancel the work if it is queued. Wait until srpt_refresh_port_work()
* finished if it is running.
*/
srpt_unregister_mad_agent(sdev);
ib_unregister_event_handler(&sdev->event_handler);
/* Cancel any work queued by the just unregistered IB event handler. */
for (i = 0; i < sdev->device->phys_port_cnt; i++)
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 22)
cancel_work_sync(&sdev->port[i].work);
#else
/*
* cancel_work_sync() was introduced in kernel 2.6.22. Older
* kernels do not have a facility to cancel scheduled work.
* kernels do not have a facility to cancel scheduled work, so
* wait until the scheduled work finished.
*/
PRINT_ERROR("%s",
"your kernel does not provide cancel_work_sync().");
flush_workqueue(&sdev->port[i].work);
#endif
scst_unregister(sdev->scst_tgt);
sdev->scst_tgt = NULL;
ib_unregister_event_handler(&sdev->event_handler);
ib_destroy_cm_id(sdev->cm_id);
ib_destroy_srq(sdev->srq);
ib_dereg_mr(sdev->mr);
ib_dealloc_pd(sdev->pd);
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 26)
class_device_unregister(&sdev->class_dev);
#else
device_unregister(&sdev->dev);
#endif
/*
* Unregistering an SCST target must happen after destroying sdev->cm_id
* such that no new SRP_LOGIN_REQ information units can arrive while
* destroying the SCST target.
*/
scst_unregister(sdev->scst_tgt);
sdev->scst_tgt = NULL;
srpt_free_ioctx_ring(sdev, sdev->ioctx_ring,
ARRAY_SIZE(sdev->ioctx_ring));
kfree(sdev);
@@ -3528,11 +3525,10 @@ static void __exit srpt_cleanup_module(void)
{
TRACE_ENTRY();
atomic_set(&cleaning_up, true);
if (srpt_thread.thread)
kthread_stop(srpt_thread.thread);
ib_unregister_client(&srpt_client);
scst_unregister_target_template(&srpt_template);
if (srpt_thread.thread)
kthread_stop(srpt_thread.thread);
class_unregister(&srpt_class);
TRACE_EXIT();