From: Karsten Graul <kgraul@linux.ibm.com>
Date: Wed, 8 Jul 2020 17:05:11 +0200
Subject: net/smc: separate LLC wait queues for flow and messages
Git-commit: 6778a6bed09b58beca936a675e9dd195c0986580
Patch-mainline: v5.8-rc5
References: jsc#SLE-13763
There might be races in scenarios where both SMC link groups are on the
same system. Prevent that by creating separate wait queues for LLC flows
and messages. Switch to non-interruptable versions of wait_event() and
wake_up() for the llc flow waiter to make sure the waiters get control
sequentially. Fine tune the llc_flow_lock to include the assignment of
the message. Write to system log when an unexpected message was
dropped. And remove an extra indirection and use the existing local
variable lgr in smc_llc_enqueue().
Fixes: 555da9af827d ("net/smc: add event-based llc_flow framework")
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
net/smc/smc_core.c | 38 ++++++++++++++----------
net/smc/smc_core.h | 4 +-
net/smc/smc_llc.c | 83 +++++++++++++++++++++++++++++++++--------------------
3 files changed, 77 insertions(+), 48 deletions(-)
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -247,7 +247,8 @@ static void smcr_lgr_link_deactivate_all
if (smc_link_usable(lnk))
lnk->state = SMC_LNK_INACTIVE;
}
- wake_up_interruptible_all(&lgr->llc_waiter);
+ wake_up_all(&lgr->llc_msg_waiter);
+ wake_up_all(&lgr->llc_flow_waiter);
}
static void smc_lgr_free(struct smc_link_group *lgr);
@@ -1130,18 +1131,19 @@ static void smcr_link_up(struct smc_link
return;
if (lgr->llc_flow_lcl.type != SMC_LLC_FLOW_NONE) {
/* some other llc task is ongoing */
- wait_event_interruptible_timeout(lgr->llc_waiter,
- (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
+ wait_event_timeout(lgr->llc_flow_waiter,
+ (list_empty(&lgr->list) ||
+ lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
SMC_LLC_WAIT_TIME);
}
- if (list_empty(&lgr->list) ||
- !smc_ib_port_active(smcibdev, ibport))
- return; /* lgr or device no longer active */
- link = smc_llc_usable_link(lgr);
- if (!link)
- return;
- smc_llc_send_add_link(link, smcibdev->mac[ibport - 1], gid,
- NULL, SMC_LLC_REQ);
+ /* lgr or device no longer active? */
+ if (!list_empty(&lgr->list) &&
+ smc_ib_port_active(smcibdev, ibport))
+ link = smc_llc_usable_link(lgr);
+ if (link)
+ smc_llc_send_add_link(link, smcibdev->mac[ibport - 1],
+ gid, NULL, SMC_LLC_REQ);
+ wake_up(&lgr->llc_flow_waiter); /* wake up next waiter */
}
}
@@ -1195,13 +1197,17 @@ static void smcr_link_down(struct smc_li
if (lgr->llc_flow_lcl.type != SMC_LLC_FLOW_NONE) {
/* another llc task is ongoing */
mutex_unlock(&lgr->llc_conf_mutex);
- wait_event_interruptible_timeout(lgr->llc_waiter,
- (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
+ wait_event_timeout(lgr->llc_flow_waiter,
+ (list_empty(&lgr->list) ||
+ lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE),
SMC_LLC_WAIT_TIME);
mutex_lock(&lgr->llc_conf_mutex);
}
- smc_llc_send_delete_link(to_lnk, del_link_id, SMC_LLC_REQ, true,
- SMC_LLC_DEL_LOST_PATH);
+ if (!list_empty(&lgr->list))
+ smc_llc_send_delete_link(to_lnk, del_link_id,
+ SMC_LLC_REQ, true,
+ SMC_LLC_DEL_LOST_PATH);
+ wake_up(&lgr->llc_flow_waiter); /* wake up next waiter */
}
}
@@ -1262,7 +1268,7 @@ static void smc_link_down_work(struct wo
if (list_empty(&lgr->list))
return;
- wake_up_interruptible_all(&lgr->llc_waiter);
+ wake_up_all(&lgr->llc_msg_waiter);
mutex_lock(&lgr->llc_conf_mutex);
smcr_link_down(link);
mutex_unlock(&lgr->llc_conf_mutex);
--- a/net/smc/smc_core.h
+++ b/net/smc/smc_core.h
@@ -262,8 +262,10 @@ struct smc_link_group {
struct work_struct llc_del_link_work;
struct work_struct llc_event_work;
/* llc event worker */
- wait_queue_head_t llc_waiter;
+ wait_queue_head_t llc_flow_waiter;
/* w4 next llc event */
+ wait_queue_head_t llc_msg_waiter;
+ /* w4 next llc msg */
struct smc_llc_flow llc_flow_lcl;
/* llc local control field */
struct smc_llc_flow llc_flow_rmt;
--- a/net/smc/smc_llc.c
+++ b/net/smc/smc_llc.c
@@ -186,6 +186,26 @@ static inline void smc_llc_flow_qentry_s
flow->qentry = qentry;
}
+static void smc_llc_flow_parallel(struct smc_link_group *lgr, u8 flow_type,
+ struct smc_llc_qentry *qentry)
+{
+ u8 msg_type = qentry->msg.raw.hdr.common.type;
+
+ if ((msg_type == SMC_LLC_ADD_LINK || msg_type == SMC_LLC_DELETE_LINK) &&
+ flow_type != msg_type && !lgr->delayed_event) {
+ lgr->delayed_event = qentry;
+ return;
+ }
+ /* drop parallel or already-in-progress llc requests */
+ if (flow_type != msg_type)
+ pr_warn_once("smc: SMC-R lg %*phN dropped parallel "
+ "LLC msg: msg %d flow %d role %d\n",
+ SMC_LGR_ID_SIZE, &lgr->id,
+ qentry->msg.raw.hdr.common.type,
+ flow_type, lgr->role);
+ kfree(qentry);
+}
+
/* try to start a new llc flow, initiated by an incoming llc msg */
static bool smc_llc_flow_start(struct smc_llc_flow *flow,
struct smc_llc_qentry *qentry)
@@ -195,14 +215,7 @@ static bool smc_llc_flow_start(struct sm
spin_lock_bh(&lgr->llc_flow_lock);
if (flow->type) {
/* a flow is already active */
- if ((qentry->msg.raw.hdr.common.type == SMC_LLC_ADD_LINK ||
- qentry->msg.raw.hdr.common.type == SMC_LLC_DELETE_LINK) &&
- !lgr->delayed_event) {
- lgr->delayed_event = qentry;
- } else {
- /* forget this llc request */
- kfree(qentry);
- }
+ smc_llc_flow_parallel(lgr, flow->type, qentry);
spin_unlock_bh(&lgr->llc_flow_lock);
return false;
}
@@ -222,8 +235,8 @@ static bool smc_llc_flow_start(struct sm
}
if (qentry == lgr->delayed_event)
lgr->delayed_event = NULL;
- spin_unlock_bh(&lgr->llc_flow_lock);
smc_llc_flow_qentry_set(flow, qentry);
+ spin_unlock_bh(&lgr->llc_flow_lock);
return true;
}
@@ -251,11 +264,11 @@ again:
return 0;
}
spin_unlock_bh(&lgr->llc_flow_lock);
- rc = wait_event_interruptible_timeout(lgr->llc_waiter,
- (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE &&
- (lgr->llc_flow_rmt.type == SMC_LLC_FLOW_NONE ||
- lgr->llc_flow_rmt.type == allowed_remote)),
- SMC_LLC_WAIT_TIME);
+ rc = wait_event_timeout(lgr->llc_flow_waiter, (list_empty(&lgr->list) ||
+ (lgr->llc_flow_lcl.type == SMC_LLC_FLOW_NONE &&
+ (lgr->llc_flow_rmt.type == SMC_LLC_FLOW_NONE ||
+ lgr->llc_flow_rmt.type == allowed_remote))),
+ SMC_LLC_WAIT_TIME * 10);
if (!rc)
return -ETIMEDOUT;
goto again;
@@ -272,7 +285,7 @@ void smc_llc_flow_stop(struct smc_link_g
flow == &lgr->llc_flow_lcl)
schedule_work(&lgr->llc_event_work);
else
- wake_up_interruptible(&lgr->llc_waiter);
+ wake_up(&lgr->llc_flow_waiter);
}
/* lnk is optional and used for early wakeup when link goes down, useful in
@@ -283,26 +296,32 @@ struct smc_llc_qentry *smc_llc_wait(stru
int time_out, u8 exp_msg)
{
struct smc_llc_flow *flow = &lgr->llc_flow_lcl;
+ u8 rcv_msg;
- wait_event_interruptible_timeout(lgr->llc_waiter,
- (flow->qentry ||
- (lnk && !smc_link_usable(lnk)) ||
- list_empty(&lgr->list)),
- time_out);
+ wait_event_timeout(lgr->llc_msg_waiter,
+ (flow->qentry ||
+ (lnk && !smc_link_usable(lnk)) ||
+ list_empty(&lgr->list)),
+ time_out);
if (!flow->qentry ||
(lnk && !smc_link_usable(lnk)) || list_empty(&lgr->list)) {
smc_llc_flow_qentry_del(flow);
goto out;
}
- if (exp_msg && flow->qentry->msg.raw.hdr.common.type != exp_msg) {
+ rcv_msg = flow->qentry->msg.raw.hdr.common.type;
+ if (exp_msg && rcv_msg != exp_msg) {
if (exp_msg == SMC_LLC_ADD_LINK &&
- flow->qentry->msg.raw.hdr.common.type ==
- SMC_LLC_DELETE_LINK) {
+ rcv_msg == SMC_LLC_DELETE_LINK) {
/* flow_start will delay the unexpected msg */
smc_llc_flow_start(&lgr->llc_flow_lcl,
smc_llc_flow_qentry_clr(flow));
return NULL;
}
+ pr_warn_once("smc: SMC-R lg %*phN dropped unexpected LLC msg: "
+ "msg %d exp %d flow %d role %d flags %x\n",
+ SMC_LGR_ID_SIZE, &lgr->id, rcv_msg, exp_msg,
+ flow->type, lgr->role,
+ flow->qentry->msg.raw.hdr.flags);
smc_llc_flow_qentry_del(flow);
}
out:
@@ -1459,7 +1478,7 @@ static void smc_llc_event_handler(struct
/* a flow is waiting for this message */
smc_llc_flow_qentry_set(&lgr->llc_flow_lcl,
qentry);
- wake_up_interruptible(&lgr->llc_waiter);
+ wake_up(&lgr->llc_msg_waiter);
} else if (smc_llc_flow_start(&lgr->llc_flow_lcl,
qentry)) {
schedule_work(&lgr->llc_add_link_work);
@@ -1474,7 +1493,7 @@ static void smc_llc_event_handler(struct
if (lgr->llc_flow_lcl.type != SMC_LLC_FLOW_NONE) {
/* a flow is waiting for this message */
smc_llc_flow_qentry_set(&lgr->llc_flow_lcl, qentry);
- wake_up_interruptible(&lgr->llc_waiter);
+ wake_up(&lgr->llc_msg_waiter);
return;
}
break;
@@ -1485,7 +1504,7 @@ static void smc_llc_event_handler(struct
/* DEL LINK REQ during ADD LINK SEQ */
smc_llc_flow_qentry_set(&lgr->llc_flow_lcl,
qentry);
- wake_up_interruptible(&lgr->llc_waiter);
+ wake_up(&lgr->llc_msg_waiter);
} else if (smc_llc_flow_start(&lgr->llc_flow_lcl,
qentry)) {
schedule_work(&lgr->llc_del_link_work);
@@ -1496,7 +1515,7 @@ static void smc_llc_event_handler(struct
/* DEL LINK REQ during ADD LINK SEQ */
smc_llc_flow_qentry_set(&lgr->llc_flow_lcl,
qentry);
- wake_up_interruptible(&lgr->llc_waiter);
+ wake_up(&lgr->llc_msg_waiter);
} else if (smc_llc_flow_start(&lgr->llc_flow_lcl,
qentry)) {
schedule_work(&lgr->llc_del_link_work);
@@ -1581,7 +1600,7 @@ static void smc_llc_rx_response(struct s
case SMC_LLC_DELETE_RKEY:
/* assign responses to the local flow, we requested them */
smc_llc_flow_qentry_set(&link->lgr->llc_flow_lcl, qentry);
- wake_up_interruptible(&link->lgr->llc_waiter);
+ wake_up(&link->lgr->llc_msg_waiter);
return;
case SMC_LLC_CONFIRM_RKEY_CONT:
/* not used because max links is 3 */
@@ -1616,7 +1635,7 @@ static void smc_llc_enqueue(struct smc_l
spin_lock_irqsave(&lgr->llc_event_q_lock, flags);
list_add_tail(&qentry->list, &lgr->llc_event_q);
spin_unlock_irqrestore(&lgr->llc_event_q_lock, flags);
- schedule_work(&link->lgr->llc_event_work);
+ schedule_work(&lgr->llc_event_work);
}
/* copy received msg and add it to the event queue */
@@ -1677,7 +1696,8 @@ void smc_llc_lgr_init(struct smc_link_gr
INIT_LIST_HEAD(&lgr->llc_event_q);
spin_lock_init(&lgr->llc_event_q_lock);
spin_lock_init(&lgr->llc_flow_lock);
- init_waitqueue_head(&lgr->llc_waiter);
+ init_waitqueue_head(&lgr->llc_flow_waiter);
+ init_waitqueue_head(&lgr->llc_msg_waiter);
mutex_init(&lgr->llc_conf_mutex);
lgr->llc_testlink_time = net->ipv4.sysctl_tcp_keepalive_time;
}
@@ -1686,7 +1706,8 @@ void smc_llc_lgr_init(struct smc_link_gr
void smc_llc_lgr_clear(struct smc_link_group *lgr)
{
smc_llc_event_flush(lgr);
- wake_up_interruptible_all(&lgr->llc_waiter);
+ wake_up_all(&lgr->llc_flow_waiter);
+ wake_up_all(&lgr->llc_msg_waiter);
cancel_work_sync(&lgr->llc_event_work);
cancel_work_sync(&lgr->llc_add_link_work);
cancel_work_sync(&lgr->llc_del_link_work);