2020-01-14 16:27:49

by Madhuparna Bhowmik

Subject: [PATCH 3/3] infiniband: sw: rdmavt: mcast.c: Use built-in RCU list checking

From: Madhuparna Bhowmik <[email protected]>

Use built-in RCU and lock-checking for list_for_each_entry_rcu()
by passing the cond argument.

Signed-off-by: Madhuparna Bhowmik <[email protected]>
---
drivers/infiniband/sw/rdmavt/mcast.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/sw/rdmavt/mcast.c b/drivers/infiniband/sw/rdmavt/mcast.c
index dd11c6fcd060..31c7f12c7665 100644
--- a/drivers/infiniband/sw/rdmavt/mcast.c
+++ b/drivers/infiniband/sw/rdmavt/mcast.c
@@ -224,7 +224,7 @@ static int rvt_mcast_add(struct rvt_dev_info *rdi, struct rvt_ibport *ibp,
}

/* Search the QP list to see if this is already there. */
- list_for_each_entry_rcu(p, &tmcast->qp_list, list) {
+ list_for_each_entry_rcu(p, &tmcast->qp_list, list, lockdep_is_held(&(ibp->lock))) {
if (p->qp == mqp->qp) {
ret = ESRCH;
goto bail;
--
2.17.1

2020-02-14 17:27:17

by Dennis Dalessandro

Subject: Re: [PATCH 3/3] infiniband: sw: rdmavt: mcast.c: Use built-in RCU list checking

On 1/14/2020 11:25 AM, [email protected] wrote:
> From: Madhuparna Bhowmik <[email protected]>
>
> Use built-in RCU and lock-checking for list_for_each_entry_rcu()
> by passing the cond argument.
>
> Signed-off-by: Madhuparna Bhowmik <[email protected]>
> ---
> drivers/infiniband/sw/rdmavt/mcast.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/infiniband/sw/rdmavt/mcast.c b/drivers/infiniband/sw/rdmavt/mcast.c
> index dd11c6fcd060..31c7f12c7665 100644
> --- a/drivers/infiniband/sw/rdmavt/mcast.c
> +++ b/drivers/infiniband/sw/rdmavt/mcast.c
> @@ -224,7 +224,7 @@ static int rvt_mcast_add(struct rvt_dev_info *rdi, struct rvt_ibport *ibp,
> }
>
> /* Search the QP list to see if this is already there. */
> - list_for_each_entry_rcu(p, &tmcast->qp_list, list) {
> + list_for_each_entry_rcu(p, &tmcast->qp_list, list, lockdep_is_held(&(ibp->lock))) {
> if (p->qp == mqp->qp) {
> ret = ESRCH;
> goto bail;
>

This one is OK. The lock is held and it is the correct one to use when
updating the list.

Reviewed-by: Dennis Dalessandro <[email protected]>