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ib_srpt: Revert r6822

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Revision 6822 triggers a race condition, hence revert it.


git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@6831 d57e44dd-8a1f-0410-8b47-8ef2f437770f
This commit is contained in:
Bart Van Assche
2016-03-18 17:00:39 +00:00
parent 8aa0ecf666
commit af8f462071
3 changed files with 6 additions and 39 deletions
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10
srpt/README
View File

@@ -68,16 +68,6 @@ The ib_srpt kernel module supports the following parameters:
to 65536 bytes, which is sufficient to use the full bandwidth of low-latency
HCAs. Increasing this value may decrease latency for applications
transferring large amounts of data at once.
* srpt_irq_qd (number, default 1)
After the ib_srpt driver has received a SCSI command from an initiator
system an interrupt is triggered. The RDMA work completion can be processed
either in interrupt context or in thread context. This parameter controls
the maximum queue depth for which RDMA completions are processed in
interrupt context. If an RDMA completion has been processed in interrupt
context the associated SCSI command will be submitted to SCST from tasklet
context. This approach helps to reduce command processing latency for
low-latency storage devices (e.g. SSDs). WARNING: setting this parameter to
a high value can cause a system to lock up.
* srpt_srq_size (number, default 4095)
ib_srpt uses a shared receive queue (SRQ) for processing incoming SRP
requests. This number may have to be increased when a large number of

33
srpt/src/ib_srpt.c
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@@ -148,12 +148,6 @@ module_param(srpt_sq_size, int, 0444);
MODULE_PARM_DESC(srpt_sq_size,
"Per-channel send queue (SQ) size.");
static int srpt_irq_qd = 1;
module_param(srpt_irq_qd, int, 0644);
MODULE_PARM_DESC(srpt_irq_qd,
"Maximum queue depth for submitting commands to SCST from IRQ context."
" WARNING: increasing this parameter may cause a system lockup.");
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 31) \
|| defined(RHEL_MAJOR) && RHEL_MAJOR -0 <= 5
static int use_port_guid_in_session_name;
@@ -196,16 +190,9 @@ MODULE_PARM_DESC(max_sge_delta, "Number to subtract from max_sge.");
* dangerous because it might cause IB completions to be processed too late
* ("IB completion for idx <n> has not been received in time").
*/
static inline enum scst_exec_context
srpt_new_iu_context(struct srpt_rdma_ch *ch)
{
return in_interrupt() &&
atomic_read(&ch->sess->sess_cmd_count) <= ch->irq_qd ?
SCST_CONTEXT_TASKLET : SCST_CONTEXT_THREAD;
}
#define srpt_xmt_rsp_context SCST_CONTEXT_THREAD
#define srpt_send_context \
(in_interrupt() ? SCST_CONTEXT_THREAD : SCST_CONTEXT_DIRECT)
static const enum scst_exec_context srpt_new_iu_context = SCST_CONTEXT_THREAD;
static const enum scst_exec_context srpt_xmt_rsp_context = SCST_CONTEXT_THREAD;
static const enum scst_exec_context srpt_send_context = SCST_CONTEXT_DIRECT;
static struct ib_client srpt_client;
static struct scst_tgt_template srpt_template;
@@ -1967,7 +1954,7 @@ static void srpt_process_rcv_completion(struct ib_cq *cq,
else
ioctx = ch->ioctx_recv_ring[index];
ioctx->byte_len = wc->byte_len;
srpt_handle_new_iu(ch, ioctx, srpt_new_iu_context(ch));
srpt_handle_new_iu(ch, ioctx, srpt_new_iu_context);
} else if (ch->state <= CH_LIVE) {
pr_info("receiving failed for idx %u with status %d\n", index,
wc->status);
@@ -1982,8 +1969,7 @@ static void srpt_process_wait_list(struct srpt_rdma_ch *ch)
list_for_each_entry_safe(recv_ioctx, tmp, &ch->cmd_wait_list,
wait_list) {
if (!srpt_handle_new_iu(ch, recv_ioctx,
srpt_new_iu_context(ch)))
if (!srpt_handle_new_iu(ch, recv_ioctx, srpt_new_iu_context))
break;
}
@@ -2112,13 +2098,7 @@ static void srpt_completion(struct ib_cq *cq, void *ctx)
{
struct srpt_rdma_ch *ch = ctx;
const int irq_qd = ch->irq_qd;
int processed = 0;
if (atomic_read(&ch->sess->sess_cmd_count) <= irq_qd)
processed = srpt_process_completion(ch, irq_qd + 1, false);
if (processed == 0 || processed > irq_qd)
wake_up_process(ch->thread);
wake_up_process(ch->thread);
}
static void srpt_free_ch(struct kref *kref)
@@ -2641,7 +2621,6 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
ch->rdma_cm.cm_id = rdma_cm_id;
rdma_cm_id->context = ch;
}
ch->irq_qd = srpt_irq_qd;
/*
* Avoid QUEUE_FULL conditions by limiting the number of buffers used
* for the SRP protocol to the SCST SCSI command queue size.

2
srpt/src/ib_srpt.h
View File

@@ -317,7 +317,6 @@ enum rdma_ch_state {
* @qp: IB queue pair used for communicating over this channel.
* @cq: IB completion queue for this channel.
* @kref: Per-channel reference count.
* @irq_qd: Maximum queue depth processed in atomic context.
* @rq_size: IB receive queue size.
* @max_sge: Maximum length of RDMA scatter list.
* @max_rsp_size: Maximum size of an SRP response message in bytes.
@@ -362,7 +361,6 @@ struct srpt_rdma_ch {
};
struct ib_cq *cq;
struct kref kref;
int irq_qd;
struct rcu_head rcu;
int rq_size;
int max_sge;