The allocation code assumes that the shadow ring cannot
be overrun because the credits will limit the allocation.
Unfortuately, the progress mechanism in sc_release_update() updates
the free count prior to processing the shadow ring, allowing the
shadow ring to be overrun by an allocation.
Reviewed-by: Mark Debbage <mark.debb...@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marcinis...@intel.com>
---
drivers/staging/rdma/hfi1/pio.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/staging/rdma/hfi1/pio.c b/drivers/staging/rdma/hfi1/pio.c
index eab58c1..8e10857 100644
--- a/drivers/staging/rdma/hfi1/pio.c
+++ b/drivers/staging/rdma/hfi1/pio.c
@@ -1565,6 +1565,7 @@ void sc_release_update(struct send_context *sc)
u64 hw_free;
u32 head, tail;
unsigned long old_free;
+ unsigned long free;
unsigned long extra;
unsigned long flags;
int code;
@@ -1579,7 +1580,7 @@ void sc_release_update(struct send_context *sc)
extra = (((hw_free & CR_COUNTER_SMASK) >> CR_COUNTER_SHIFT)
- (old_free & CR_COUNTER_MASK))
& CR_COUNTER_MASK;
- sc->free = old_free + extra;
+ free = old_free + extra;
trace_hfi1_piofree(sc, extra);
/* call sent buffer callbacks */
@@ -1589,7 +1590,7 @@ void sc_release_update(struct send_context *sc)
while (head != tail) {
pbuf = &sc->sr[tail].pbuf;
- if (sent_before(sc->free, pbuf->sent_at)) {
+ if (sent_before(free, pbuf->sent_at)) {
/* not sent yet */
break;
}
@@ -1603,8 +1604,10 @@ void sc_release_update(struct send_context *sc)
if (tail >= sc->sr_size)
tail = 0;
}
- /* update tail, in case we moved it */
sc->sr_tail = tail;
+ /* make sure tail is updated before free */
+ smp_wmb();
+ sc->free = free;
spin_unlock_irqrestore(&sc->release_lock, flags);
sc_piobufavail(sc);
}
--
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