[PATCH 08/28] staging/lustre/ptlrpc: missing wakeup for ptlrpc_check_set

Oleg Drokin
2016-06-20T02:10:28Z

From: Liang Zhen <liang.zhen@intel.com>

This patch changes a few things:

- There is no guarantee that request_out_callback will happen
before reply_in_callback, if a request got reply and unlinked
reply buffer before request_out_callback is called, then the
thread waiting on ptlrpc_request_set will miss wakeup event.

This may seriously impact performance of some IO workloads or
result in RPC timeout

- To make code more easier to understand, this patch changes
action-bits "rq_req_unlink" and "rq_reply_unlink" to
status-bits "rq_req_unlinked" and "rq_reply_unlinked"

Signed-off-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-on: http://review.whamcloud.com/12158
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5696
Reviewed-by: Johann Lombardi <johann.lombardi@intel.com>
Reviewed-by: Li Wei <wei.g.li@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
---
drivers/staging/lustre/lustre/include/lustre_net.h | 27 +++++++++++++---------
drivers/staging/lustre/lustre/ptlrpc/client.c | 12 ++++------
drivers/staging/lustre/lustre/ptlrpc/events.c | 22 +++++++++++-------
drivers/staging/lustre/lustre/ptlrpc/niobuf.c | 14 +++++------
.../staging/lustre/lustre/ptlrpc/ptlrpc_internal.h | 9 ++++++++
5 files changed, 51 insertions(+), 33 deletions(-)

diff --git a/drivers/staging/lustre/lustre/include/lustre_net.h b/drivers/staging/lustre/lustre/include/lustre_net.h
index 5968c3c..523d082 100644
--- a/drivers/staging/lustre/lustre/include/lustre_net.h
+++ b/drivers/staging/lustre/lustre/include/lustre_net.h
@@ -1428,7 +1428,7 @@ struct ptlrpc_request {
* rq_list
*/
spinlock_t rq_lock;
- /** client-side flags are serialized by rq_lock */
+ /** client-side flags are serialized by rq_lock @{ */
unsigned int rq_intr:1, rq_replied:1, rq_err:1,
rq_timedout:1, rq_resend:1, rq_restart:1,
/**
@@ -1444,18 +1444,15 @@ struct ptlrpc_request {
rq_no_resend:1, rq_waiting:1, rq_receiving_reply:1,
rq_no_delay:1, rq_net_err:1, rq_wait_ctx:1,
rq_early:1,
- rq_req_unlink:1, rq_reply_unlink:1,
+ rq_req_unlinked:1, /* unlinked request buffer from lnet */
+ rq_reply_unlinked:1, /* unlinked reply buffer from lnet */
rq_memalloc:1, /* req originated from "kswapd" */
- /* server-side flags */
- rq_packed_final:1, /* packed final reply */
- rq_hp:1, /* high priority RPC */
- rq_at_linked:1, /* link into service's srv_at_array */
- rq_reply_truncate:1,
rq_committed:1,
- /* whether the "rq_set" is a valid one */
+ rq_reply_truncated:1,
+ /** whether the "rq_set" is a valid one */
rq_invalid_rqset:1,
rq_generation_set:1,
- /* do not resend request on -EINPROGRESS */
+ /** do not resend request on -EINPROGRESS */
rq_no_retry_einprogress:1,
/* allow the req to be sent if the import is in recovery
* status
@@ -1463,6 +1460,14 @@ struct ptlrpc_request {
rq_allow_replay:1,
/* bulk request, sent to server, but uncommitted */
rq_unstable:1;
+ /** @} */
+
+ /** server-side flags @{ */
+ unsigned int
+ rq_hp:1, /**< high priority RPC */
+ rq_at_linked:1, /**< link into service's srv_at_array */
+ rq_packed_final:1; /**< packed final reply */
+ /** @} */

/** one of RQ_PHASE_* */
enum rq_phase rq_phase;
@@ -2785,8 +2790,8 @@ ptlrpc_client_recv_or_unlink(struct ptlrpc_request *req)
spin_unlock(&req->rq_lock);
return 1;
}
- rc = req->rq_receiving_reply;
- rc = rc || req->rq_req_unlink || req->rq_reply_unlink;
+ rc = !req->rq_req_unlinked || !req->rq_reply_unlinked ||
+ req->rq_receiving_reply;
spin_unlock(&req->rq_lock);
return rc;
}
diff --git a/drivers/staging/lustre/lustre/ptlrpc/client.c b/drivers/staging/lustre/lustre/ptlrpc/client.c
index 9abd469..ae1cef3 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/client.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/client.c
@@ -1148,9 +1148,9 @@ static int after_reply(struct ptlrpc_request *req)

LASSERT(obd);
/* repbuf must be unlinked */
- LASSERT(!req->rq_receiving_reply && !req->rq_reply_unlink);
+ LASSERT(!req->rq_receiving_reply && req->rq_reply_unlinked);

- if (req->rq_reply_truncate) {
+ if (req->rq_reply_truncated) {
if (ptlrpc_no_resend(req)) {
DEBUG_REQ(D_ERROR, req, "reply buffer overflow, expected: %d, actual size: %d",
req->rq_nob_received, req->rq_repbuf_len);
@@ -2342,9 +2342,10 @@ int ptlrpc_unregister_reply(struct ptlrpc_request *request, int async)

LASSERT(rc == -ETIMEDOUT);
DEBUG_REQ(D_WARNING, request,
- "Unexpectedly long timeout rvcng=%d unlnk=%d/%d",
+ "Unexpectedly long timeout receiving_reply=%d req_ulinked=%d reply_unlinked=%d",
request->rq_receiving_reply,
- request->rq_req_unlink, request->rq_reply_unlink);
+ request->rq_req_unlinked,
+ request->rq_reply_unlinked);
}
return 0;
}
@@ -3002,9 +3003,6 @@ void *ptlrpcd_alloc_work(struct obd_import *imp,
req->rq_import = class_import_get(imp);
req->rq_interpret_reply = work_interpreter;
/* don't want reply */
- req->rq_receiving_reply = 0;
- req->rq_req_unlink = 0;
- req->rq_reply_unlink = 0;
req->rq_no_delay = 1;
req->rq_no_resend = 1;
req->rq_pill.rc_fmt = (void *)&worker_format;
diff --git a/drivers/staging/lustre/lustre/ptlrpc/events.c b/drivers/staging/lustre/lustre/ptlrpc/events.c
index 95be4aa..a243342 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/events.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/events.c
@@ -51,27 +51,33 @@ void request_out_callback(lnet_event_t *ev)
{
struct ptlrpc_cb_id *cbid = ev->md.user_ptr;
struct ptlrpc_request *req = cbid->cbid_arg;
+ bool wakeup = false;

- LASSERT(ev->type == LNET_EVENT_SEND ||
- ev->type == LNET_EVENT_UNLINK);
+ LASSERT(ev->type == LNET_EVENT_SEND || ev->type == LNET_EVENT_UNLINK);
LASSERT(ev->unlinked);

DEBUG_REQ(D_NET, req, "type %d, status %d", ev->type, ev->status);

sptlrpc_request_out_callback(req);
+
spin_lock(&req->rq_lock);
req->rq_real_sent = ktime_get_real_seconds();
- if (ev->unlinked)
- req->rq_req_unlink = 0;
+ req->rq_req_unlinked = 1;
+ /* reply_in_callback happened before request_out_callback? */
+ if (req->rq_reply_unlinked)
+ wakeup = true;

if (ev->type == LNET_EVENT_UNLINK || ev->status != 0) {
/* Failed send: make it seem like the reply timed out, just
* like failing sends in client.c does currently...
*/
-
req->rq_net_err = 1;
- ptlrpc_client_wake_req(req);
+ wakeup = true;
}
+
+ if (wakeup)
+ ptlrpc_client_wake_req(req);
+
spin_unlock(&req->rq_lock);

ptlrpc_req_finished(req);
@@ -100,7 +106,7 @@ void reply_in_callback(lnet_event_t *ev)
req->rq_receiving_reply = 0;
req->rq_early = 0;
if (ev->unlinked)
- req->rq_reply_unlink = 0;
+ req->rq_reply_unlinked = 1;

if (ev->status)
goto out_wake;
@@ -114,7 +120,7 @@ void reply_in_callback(lnet_event_t *ev)
if (ev->mlength < ev->rlength) {
CDEBUG(D_RPCTRACE, "truncate req %p rpc %d - %d+%d\n", req,
req->rq_replen, ev->rlength, ev->offset);
- req->rq_reply_truncate = 1;
+ req->rq_reply_truncated = 1;
req->rq_replied = 1;
req->rq_status = -EOVERFLOW;
req->rq_nob_received = ev->rlength + ev->offset;
diff --git a/drivers/staging/lustre/lustre/ptlrpc/niobuf.c b/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
index 4e7d68f..8c49f5e 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
+++ b/drivers/staging/lustre/lustre/ptlrpc/niobuf.c
@@ -577,19 +577,18 @@ int ptl_send_rpc(struct ptlrpc_request *request, int noreply)
}

spin_lock(&request->rq_lock);
- /* If the MD attach succeeds, there _will_ be a reply_in callback */
- request->rq_receiving_reply = !noreply;
- request->rq_req_unlink = 1;
/* We are responsible for unlinking the reply buffer */
- request->rq_reply_unlink = !noreply;
+ request->rq_reply_unlinked = noreply;
+ request->rq_receiving_reply = !noreply;
/* Clear any flags that may be present from previous sends. */
+ request->rq_req_unlinked = 0;
request->rq_replied = 0;
request->rq_err = 0;
request->rq_timedout = 0;
request->rq_net_err = 0;
request->rq_resend = 0;
request->rq_restart = 0;
- request->rq_reply_truncate = 0;
+ request->rq_reply_truncated = 0;
spin_unlock(&request->rq_lock);

if (!noreply) {
@@ -604,7 +603,7 @@ int ptl_send_rpc(struct ptlrpc_request *request, int noreply)
reply_md.user_ptr = &request->rq_reply_cbid;
reply_md.eq_handle = ptlrpc_eq_h;

- /* We must see the unlink callback to unset rq_reply_unlink,
+ /* We must see the unlink callback to set rq_reply_unlinked,
* so we can't auto-unlink
*/
rc = LNetMDAttach(reply_me_h, reply_md, LNET_RETAIN,
@@ -651,9 +650,10 @@ int ptl_send_rpc(struct ptlrpc_request *request, int noreply)
connection,
request->rq_request_portal,
request->rq_xid, 0);
- if (rc == 0)
+ if (likely(rc == 0))
goto out;

+ request->rq_req_unlinked = 1;
ptlrpc_req_finished(request);
if (noreply)
goto out;
diff --git a/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_internal.h b/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_internal.h
index d3674cb..a9831fa 100644
--- a/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_internal.h
+++ b/drivers/staging/lustre/lustre/ptlrpc/ptlrpc_internal.h
@@ -304,6 +304,15 @@ static inline void ptlrpc_cli_req_init(struct ptlrpc_request *req)
struct ptlrpc_cli_req *cr = &req->rq_cli;

ptlrpc_req_comm_init(req);
+
+ req->rq_receiving_reply = 0;
+ req->rq_req_unlinked = 1;
+ req->rq_reply_unlinked = 1;
+
+ req->rq_receiving_reply = 0;
+ req->rq_req_unlinked = 1;
+ req->rq_reply_unlinked = 1;
+
INIT_LIST_HEAD(&cr->cr_set_chain);
INIT_LIST_HEAD(&cr->cr_ctx_chain);
init_waitqueue_head(&cr->cr_reply_waitq);
--
2.7.4