From: Andreea-Cristina Bernat <[email protected]> According to RCU_INIT_POINTER()'s block comment 3.a, it can be used if "1. This use of RCU_INIT_POINTER() is NULLing out the pointer" it is better to use it instead of rcu_assign_pointer() because it has a smaller overhead.
"3. The referenced data structure has already been exposed to readers either at compile time or via rcu_assign_pointer() -and- a. You have not made -any- reader-visible changes to this structure since then". These cases fulfill the conditions above because between the rcu_dereference_protected() call and the rcu_assign_pointer() call there is no update of that value. Therefore, this patch makes the replacement. The following Coccinelle semantic patch was used: @@ @@ - rcu_assign_pointer + RCU_INIT_POINTER (..., ( rtnl_dereference(...) | rcu_dereference_protected(...) ) ) [consolidated from http://marc.info/?l=linux-rdma&m=140836578119485&w=2 and http://marc.info/?l=linux-rdma&m=140906361403047&w=2] Tested-by: Mike Marciniszyn <[email protected]> Signed-off-by: Andreea-Cristina Bernat <[email protected]> Signed-off-by: Mike Marciniszyn <[email protected]> --- drivers/infiniband/hw/qib/qib_qp.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/hw/qib/qib_qp.c b/drivers/infiniband/hw/qib/qib_qp.c index 6ddc026..4fa88ba 100644 --- a/drivers/infiniband/hw/qib/qib_qp.c +++ b/drivers/infiniband/hw/qib/qib_qp.c @@ -255,10 +255,10 @@ static void remove_qp(struct qib_ibdev *dev, struct qib_qp *qp) if (rcu_dereference_protected(ibp->qp0, lockdep_is_held(&dev->qpt_lock)) == qp) { - rcu_assign_pointer(ibp->qp0, NULL); + RCU_INIT_POINTER(ibp->qp0, NULL); } else if (rcu_dereference_protected(ibp->qp1, lockdep_is_held(&dev->qpt_lock)) == qp) { - rcu_assign_pointer(ibp->qp1, NULL); + RCU_INIT_POINTER(ibp->qp1, NULL); } else { struct qib_qp *q; struct qib_qp __rcu **qpp; @@ -269,7 +269,7 @@ static void remove_qp(struct qib_ibdev *dev, struct qib_qp *qp) lockdep_is_held(&dev->qpt_lock))) != NULL; qpp = &q->next) if (q == qp) { - rcu_assign_pointer(*qpp, + RCU_INIT_POINTER(*qpp, rcu_dereference_protected(qp->next, lockdep_is_held(&dev->qpt_lock))); removed = 1; @@ -315,7 +315,7 @@ unsigned qib_free_all_qps(struct qib_devdata *dd) for (n = 0; n < dev->qp_table_size; n++) { qp = rcu_dereference_protected(dev->qp_table[n], lockdep_is_held(&dev->qpt_lock)); - rcu_assign_pointer(dev->qp_table[n], NULL); + RCU_INIT_POINTER(dev->qp_table[n], NULL); for (; qp; qp = rcu_dereference_protected(qp->next, lockdep_is_held(&dev->qpt_lock))) -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
