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authorDakshaja Uppalapati <dakshaja@chelsio.com>2021-08-05 18:13:32 +0530
committerJason Gunthorpe <jgg@nvidia.com>2021-08-05 22:33:00 -0300
commit2638a32348bbb1c384dbbd515fd2b12c155f0188 (patch)
tree9fb7afbc32e8c6172a2cac36a79c88e51b5aefb1
parent8b436a99cd708bd158231a0630ffa49b1d6175e4 (diff)
downloadlinux-2638a32348bbb1c384dbbd515fd2b12c155f0188.tar.bz2
RDMA/iw_cxgb4: Fix refcount underflow while destroying cqs.
Previous atomic increment/decrement logic expects the atomic count to be '0' after the final decrement. Replacing atomic count with refcount does not allow that, as refcount_dec() considers count of 1 as underflow and triggers a kernel splat. Fix the current refcount logic by using the usual pattern of decrementing the refcount and test if it is '0' on the final deref in c4iw_destroy_cq(). Use wait_for_completion() instead of wait_event(). Fixes: 7183451f846d ("RDMA/cxgb4: Use refcount_t instead of atomic_t for reference counting") Link: https://lore.kernel.org/r/1628167412-12114-1-git-send-email-dakshaja@chelsio.com Signed-off-by: Dakshaja Uppalapati <dakshaja@chelsio.com> Reviewed-by: Potnuri Bharat Teja <bharat@chelsio.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
-rw-r--r--drivers/infiniband/hw/cxgb4/cq.c12
-rw-r--r--drivers/infiniband/hw/cxgb4/ev.c6
-rw-r--r--drivers/infiniband/hw/cxgb4/iw_cxgb4.h3
3 files changed, 13 insertions, 8 deletions
diff --git a/drivers/infiniband/hw/cxgb4/cq.c b/drivers/infiniband/hw/cxgb4/cq.c
index 6c8c910f4e86..c7e8d7b3baa1 100644
--- a/drivers/infiniband/hw/cxgb4/cq.c
+++ b/drivers/infiniband/hw/cxgb4/cq.c
@@ -967,6 +967,12 @@ int c4iw_poll_cq(struct ib_cq *ibcq, int num_entries, struct ib_wc *wc)
return !err || err == -ENODATA ? npolled : err;
}
+void c4iw_cq_rem_ref(struct c4iw_cq *chp)
+{
+ if (refcount_dec_and_test(&chp->refcnt))
+ complete(&chp->cq_rel_comp);
+}
+
int c4iw_destroy_cq(struct ib_cq *ib_cq, struct ib_udata *udata)
{
struct c4iw_cq *chp;
@@ -976,8 +982,8 @@ int c4iw_destroy_cq(struct ib_cq *ib_cq, struct ib_udata *udata)
chp = to_c4iw_cq(ib_cq);
xa_erase_irq(&chp->rhp->cqs, chp->cq.cqid);
- refcount_dec(&chp->refcnt);
- wait_event(chp->wait, !refcount_read(&chp->refcnt));
+ c4iw_cq_rem_ref(chp);
+ wait_for_completion(&chp->cq_rel_comp);
ucontext = rdma_udata_to_drv_context(udata, struct c4iw_ucontext,
ibucontext);
@@ -1081,7 +1087,7 @@ int c4iw_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
spin_lock_init(&chp->lock);
spin_lock_init(&chp->comp_handler_lock);
refcount_set(&chp->refcnt, 1);
- init_waitqueue_head(&chp->wait);
+ init_completion(&chp->cq_rel_comp);
ret = xa_insert_irq(&rhp->cqs, chp->cq.cqid, chp, GFP_KERNEL);
if (ret)
goto err_destroy_cq;
diff --git a/drivers/infiniband/hw/cxgb4/ev.c b/drivers/infiniband/hw/cxgb4/ev.c
index 7798d090888b..34211a533d5c 100644
--- a/drivers/infiniband/hw/cxgb4/ev.c
+++ b/drivers/infiniband/hw/cxgb4/ev.c
@@ -213,8 +213,7 @@ void c4iw_ev_dispatch(struct c4iw_dev *dev, struct t4_cqe *err_cqe)
break;
}
done:
- if (refcount_dec_and_test(&chp->refcnt))
- wake_up(&chp->wait);
+ c4iw_cq_rem_ref(chp);
c4iw_qp_rem_ref(&qhp->ibqp);
out:
return;
@@ -234,8 +233,7 @@ int c4iw_ev_handler(struct c4iw_dev *dev, u32 qid)
spin_lock_irqsave(&chp->comp_handler_lock, flag);
(*chp->ibcq.comp_handler)(&chp->ibcq, chp->ibcq.cq_context);
spin_unlock_irqrestore(&chp->comp_handler_lock, flag);
- if (refcount_dec_and_test(&chp->refcnt))
- wake_up(&chp->wait);
+ c4iw_cq_rem_ref(chp);
} else {
pr_debug("unknown cqid 0x%x\n", qid);
xa_unlock_irqrestore(&dev->cqs, flag);
diff --git a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
index 3883af3d2312..ac5f581aff4c 100644
--- a/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
+++ b/drivers/infiniband/hw/cxgb4/iw_cxgb4.h
@@ -428,7 +428,7 @@ struct c4iw_cq {
spinlock_t lock;
spinlock_t comp_handler_lock;
refcount_t refcnt;
- wait_queue_head_t wait;
+ struct completion cq_rel_comp;
struct c4iw_wr_wait *wr_waitp;
};
@@ -979,6 +979,7 @@ struct ib_mr *c4iw_reg_user_mr(struct ib_pd *pd, u64 start,
struct ib_mr *c4iw_get_dma_mr(struct ib_pd *pd, int acc);
int c4iw_dereg_mr(struct ib_mr *ib_mr, struct ib_udata *udata);
int c4iw_destroy_cq(struct ib_cq *ib_cq, struct ib_udata *udata);
+void c4iw_cq_rem_ref(struct c4iw_cq *chp);
int c4iw_create_cq(struct ib_cq *ibcq, const struct ib_cq_init_attr *attr,
struct ib_udata *udata);
int c4iw_arm_cq(struct ib_cq *ibcq, enum ib_cq_notify_flags flags);