From: Jubin John <jubin.john@xxxxxxxxx>
hrtimer functions do not guarantee serialization, so we extend the
cca_timer_lock to cover the hrtimer_forward_now() in the hrtimer
callback handler and the hrtimer_start() in process_becn(). This
prevents races between these 2 functions to update the hrtimer state
leading to problems such as:
kernel BUG at kernel/hrtimer.c:1282!
encountered during validation of the CCA feature.
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@xxxxxxxxx>
Signed-off-by: Jubin John <jubin.john@xxxxxxxxx>
---
drivers/staging/rdma/hfi1/init.c | 20 +++++++++-----------
drivers/staging/rdma/hfi1/rc.c | 7 +++----
2 files changed, 12 insertions(+), 15 deletions(-)
diff --git a/drivers/staging/rdma/hfi1/init.c b/drivers/staging/rdma/hfi1/init.c
index 991a49d..7be814f 100644
--- a/drivers/staging/rdma/hfi1/init.c
+++ b/drivers/staging/rdma/hfi1/init.c
@@ -422,9 +422,10 @@ static enum hrtimer_restart cca_timer_fn(struct hrtimer *t)
struct cca_timer *cca_timer;
struct hfi1_pportdata *ppd;
int sl;
- u16 ccti, ccti_timer, ccti_min;
+ u16 ccti_timer, ccti_min;
struct cc_state *cc_state;
unsigned long flags;
+ enum hrtimer_restart ret = HRTIMER_NORESTART;
cca_timer = container_of(t, struct cca_timer, hrtimer);
ppd = cca_timer->ppd;
@@ -450,24 +451,21 @@ static enum hrtimer_restart cca_timer_fn(struct hrtimer *t)
spin_lock_irqsave(&ppd->cca_timer_lock, flags);
- ccti = cca_timer->ccti;
-
- if (ccti > ccti_min) {
+ if (cca_timer->ccti > ccti_min) {
cca_timer->ccti--;
set_link_ipg(ppd);
}
- spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);
-
- rcu_read_unlock();
-
- if (ccti > ccti_min) {
+ if (cca_timer->ccti > ccti_min) {
unsigned long nsec = 1024 * ccti_timer;
/* ccti_timer is in units of 1.024 usec */
hrtimer_forward_now(t, ns_to_ktime(nsec));
- return HRTIMER_RESTART;
+ ret = HRTIMER_RESTART;
}
- return HRTIMER_NORESTART;
+
+ spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);
+ rcu_read_unlock();
+ return ret;
}
/*
diff --git a/drivers/staging/rdma/hfi1/rc.c b/drivers/staging/rdma/hfi1/rc.c
index c614779..792f15e 100644
--- a/drivers/staging/rdma/hfi1/rc.c
+++ b/drivers/staging/rdma/hfi1/rc.c
@@ -2021,8 +2021,6 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn,
if (sl >= OPA_MAX_SLS)
return;
- cca_timer = &ppd->cca_timer[sl];
-
cc_state = get_cc_state(ppd);
if (!cc_state)
@@ -2041,6 +2039,7 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn,
spin_lock_irqsave(&ppd->cca_timer_lock, flags);
+ cca_timer = &ppd->cca_timer[sl];
if (cca_timer->ccti < ccti_limit) {
if (cca_timer->ccti + ccti_incr <= ccti_limit)
cca_timer->ccti += ccti_incr;
@@ -2049,8 +2048,6 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn,
set_link_ipg(ppd);
}
- spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);
-
ccti = cca_timer->ccti;
if (!hrtimer_active(&cca_timer->hrtimer)) {
@@ -2061,6 +2058,8 @@ void process_becn(struct hfi1_pportdata *ppd, u8 sl, u16 rlid, u32 lqpn,
HRTIMER_MODE_REL);
}
+ spin_unlock_irqrestore(&ppd->cca_timer_lock, flags);
+
if ((trigger_threshold != 0) && (ccti >= trigger_threshold))
log_cca_event(ppd, sl, rlid, lqpn, rqpn, svc_type);
}
--
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