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ib_srpt: Fix a few (theoretical ?) race conditions

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git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@4278 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2012-05-03 11:00:39 +00:00
parent 30cfdfd079
commit 8f334bd78e
2 changed files with 79 additions and 36 deletions
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113
srpt/src/ib_srpt.c
View File

@@ -1991,6 +1991,20 @@ static void srpt_completion(struct ib_cq *cq, void *ctx)
wake_up_process(ch->thread);
}
static void srpt_free_ch(struct kref *kref)
{
struct srpt_rdma_ch *ch = container_of(kref, struct srpt_rdma_ch, kref);
/*
* The function call below will wait for the completion handler
* callback to finish and hence ensures that wake_up_process() won't
* be invoked anymore from that callback for the current thread.
*/
srpt_destroy_ch_ib(ch);
kfree(ch);
}
static int srpt_compl_thread(void *arg)
{
struct srpt_rdma_ch *ch;
@@ -2027,7 +2041,7 @@ static int srpt_compl_thread(void *arg)
barrier();
#endif
#endif
while (!ch->last_wqe_received) {
while (!ch->last_wqe_received && ch->state == CH_LIVE) {
srpt_process_completion(ch->cq, ch, SCST_CONTEXT_THREAD,
SCST_CONTEXT_THREAD);
schedule();
@@ -2062,17 +2076,13 @@ static int srpt_compl_thread(void *arg)
list_del(&ch->list);
spin_unlock_irq(&sdev->spinlock);
/*
* If the connection is still established, ib_destroy_cm_id() will
* send a DREQ.
*/
ib_destroy_cm_id(ch->cm_id);
/*
* The function call below will wait for the completion handler
* callback to finish and hence ensures that wake_up_process() won't
* be invoked anymore from that callback for the current thread.
*/
srpt_destroy_ch_ib(ch);
kfree(ch);
ch = NULL;
kref_put(&ch->kref, srpt_free_ch);
wake_up(&sdev->ch_releaseQ);
@@ -2189,15 +2199,19 @@ static void srpt_destroy_ch_ib(struct srpt_rdma_ch *ch)
*
* Returns true if and only if the channel state has been modified from
* CH_CONNECTING or CH_LIVE into CH_DISCONNECTING.
*
* Note: The caller must hold ch->sport->sdev->spinlock.
*/
static bool __srpt_close_ch(struct srpt_rdma_ch *ch)
__releases(&ch->srpt_tgt->spinlock)
__acquires(&ch->srpt_tgt->spinlock)
{
struct srpt_device *sdev = ch->sport->sdev;
enum rdma_ch_state prev_state;
int ret;
bool was_live;
BUG_ON(!ch->cm_id);
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 32)
lockdep_assert_held(&sdev->spinlock);
#endif
was_live = false;
@@ -2205,27 +2219,32 @@ static bool __srpt_close_ch(struct srpt_rdma_ch *ch)
switch (prev_state) {
case CH_CONNECTING:
ib_send_cm_rej(ch->cm_id, IB_CM_REJ_NO_RESOURCES, NULL, 0,
NULL, 0);
/* fall through */
case CH_LIVE:
was_live = true;
if (ib_send_cm_dreq(ch->cm_id, NULL, 0) < 0)
PRINT_ERROR("sending CM DREQ failed.");
break;
case CH_DISCONNECTING:
case CH_DRAINING:
break;
}
if (was_live) {
kref_get(&ch->kref);
spin_unlock_irq(&sdev->spinlock);
ret = srpt_ch_qp_err(ch);
if (ret < 0)
PRINT_ERROR("Setting queue pair in error state"
" failed: %d", ret);
kref_put(&ch->kref, srpt_free_ch);
spin_lock_irq(&sdev->spinlock);
}
return was_live;
}
/**
* srpt_close_ch() - Close an RDMA channel.
*
* Note: Must be called from inside an IB CM callback since otherwise it's not
* guaranteed that ch->cm_id won't be destroyed from another thread.
*/
static void srpt_close_ch(struct srpt_rdma_ch *ch)
{
@@ -2265,6 +2284,22 @@ static void srpt_drain_channel(struct ib_cm_id *cm_id)
}
}
static void __srpt_close_all_ch(struct srpt_device *sdev)
{
struct srpt_rdma_ch *ch, *next_ch;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 32)
lockdep_assert_held(&sdev->spinlock);
#endif
list_for_each_entry_safe(ch, next_ch, &sdev->rch_list, list) {
PRINT_INFO("Closing channel %s because target %s has been"
" disabled", ch->sess_name,
sdev->scst_tgt->tgt_name);
__srpt_close_ch(ch);
}
}
#if !defined(CONFIG_SCST_PROC)
/**
* srpt_enable_target() - Allows to enable a target via sysfs.
@@ -2283,17 +2318,8 @@ static int srpt_enable_target(struct scst_tgt *scst_tgt, bool enable)
spin_lock_irq(&sdev->spinlock);
sdev->enabled = enable;
if (!enable) {
struct srpt_rdma_ch *ch;
list_for_each_entry(ch, &sdev->rch_list, list) {
PRINT_INFO("Closing channel %s (cm_id %p)"
" because target %s has been disabled",
ch->sess_name, ch->cm_id,
sdev->device->name);
__srpt_close_ch(ch);
}
}
if (!enable)
__srpt_close_all_ch(sdev);
spin_unlock_irq(&sdev->spinlock);
return 0;
@@ -2392,7 +2418,7 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
goto reject;
}
if (!srpt_is_target_enabled(sdev->scst_tgt)) {
if (!sdev->enabled) {
rej->reason = cpu_to_be32(
SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
PRINT_ERROR("rejected SRP_LOGIN_REQ because the target %s (%s)"
@@ -2419,6 +2445,7 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
goto reject;
}
kref_init(&ch->kref);
memcpy(ch->i_port_id, req->initiator_port_id, 16);
memcpy(ch->t_port_id, req->target_port_id, 16);
ch->sport = &sdev->port[param->port - 1];
@@ -2503,10 +2530,12 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
}
spin_lock_irq(&sdev->spinlock);
if ((req->req_flags & SRP_MTCH_ACTION) == SRP_MULTICHAN_SINGLE) {
struct srpt_rdma_ch *ch2;
rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_NO_CHAN;
restart:
list_for_each_entry(ch2, &sdev->rch_list, list) {
if (!memcmp(ch2->i_port_id, req->initiator_port_id, 16)
&& !memcmp(ch2->t_port_id, req->target_port_id, 16)
@@ -2521,13 +2550,27 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
rsp->rsp_flags =
SRP_LOGIN_RSP_MULTICHAN_TERMINATED;
goto restart;
}
}
} else {
rsp->rsp_flags = SRP_LOGIN_RSP_MULTICHAN_MAINTAINED;
}
list_add_tail(&ch->list, &sdev->rch_list);
ch->thread = thread;
if (!sdev->enabled) {
rej->reason = cpu_to_be32(
SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
PRINT_ERROR("rejected SRP_LOGIN_REQ because the target %s (%s)"
" is not enabled",
sdev->scst_tgt->tgt_name, sdev->device->name);
spin_unlock_irq(&sdev->spinlock);
goto reject;
}
spin_unlock_irq(&sdev->spinlock);
ret = srpt_ch_qp_rtr(ch, ch->qp);
@@ -2612,7 +2655,6 @@ reject:
sizeof(*rej));
if (ch && ch->thread) {
srpt_drain_channel(cm_id);
srpt_close_ch(ch);
/*
* Tell the caller not to free cm_id since
@@ -3412,8 +3454,7 @@ static int srpt_release_sdev(struct srpt_device *sdev)
/* Disallow new logins and close all active sessions. */
spin_lock_irq(&sdev->spinlock);
sdev->enabled = false;
list_for_each_entry(ch, &sdev->rch_list, list)
__srpt_close_ch(ch);
__srpt_close_all_ch(sdev);
spin_unlock_irq(&sdev->spinlock);
while (wait_event_timeout(sdev->ch_releaseQ,

2
srpt/src/ib_srpt.h
View File

@@ -287,6 +287,7 @@ enum rdma_ch_state {
* @cm_id: IB CM ID associated with the channel.
* @qp: IB queue pair used for communicating over this channel.
* @cq: IB completion queue for this channel.
* @kref: Per-channel reference count.
* @rq_size: IB receive queue size.
* @max_sge: Maximum length of RDMA scatter list.
* @sq_wr_avail: number of work requests available in the send queue.
@@ -319,6 +320,7 @@ struct srpt_rdma_ch {
struct ib_cm_id *cm_id;
struct ib_qp *qp;
struct ib_cq *cq;
struct kref kref;
int rq_size;
int max_sge;
int max_rsp_size;