From: Bart Van Assche <bart.vanassche@wdc.com>
Date: Tue, 16 Jan 2018 16:14:05 -0800
Subject: IB/srpt: Make it safe to use RCU for srpt_device.rch_list
Patch-mainline: v4.16-rc1
Git-commit: 795bc112cd5a40e7612313f54ee527198b1e734f
References: bsc#1103992 FATE#326009
The next patch will iterate over rch_list from a context from which
it is not allowed to block. Hence make rch_list RCU-safe.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/infiniband/ulp/srpt/ib_srpt.c | 13 ++++++++++---
drivers/infiniband/ulp/srpt/ib_srpt.h | 2 ++
2 files changed, 12 insertions(+), 3 deletions(-)
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -1906,7 +1906,7 @@ static void srpt_free_ch(struct kref *kr
{
struct srpt_rdma_ch *ch = container_of(kref, struct srpt_rdma_ch, kref);
- kfree(ch);
+ kfree_rcu(ch, rcu);
}
static void srpt_release_channel_work(struct work_struct *w)
@@ -1945,11 +1945,17 @@ static void srpt_release_channel_work(st
srp_max_req_size, DMA_FROM_DEVICE);
mutex_lock(&sdev->mutex);
- list_del_init(&ch->list);
+ list_del_rcu(&ch->list);
if (ch->release_done)
complete(ch->release_done);
mutex_unlock(&sdev->mutex);
+ synchronize_rcu();
+
+ mutex_lock(&sdev->mutex);
+ INIT_LIST_HEAD(&ch->list);
+ mutex_unlock(&sdev->mutex);
+
wake_up(&sdev->ch_releaseQ);
kref_put(&ch->kref, srpt_free_ch);
@@ -2064,6 +2070,7 @@ static int srpt_cm_req_recv(struct ib_cm
goto reject;
}
+ init_rcu_head(&ch->rcu);
kref_init(&ch->kref);
ch->zw_cqe.done = srpt_zerolength_write_done;
INIT_WORK(&ch->release_work, srpt_release_channel_work);
@@ -2190,7 +2197,7 @@ static int srpt_cm_req_recv(struct ib_cm
}
mutex_lock(&sdev->mutex);
- list_add_tail(&ch->list, &sdev->rch_list);
+ list_add_tail_rcu(&ch->list, &sdev->rch_list);
mutex_unlock(&sdev->mutex);
goto out;
--- a/drivers/infiniband/ulp/srpt/ib_srpt.h
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.h
@@ -244,6 +244,7 @@ enum rdma_ch_state {
* @qp: IB queue pair used for communicating over this channel.
* @cq: IB completion queue for this channel.
* @zw_cqe: Zero-length write CQE.
+ * @rcu: RCU head.
* @kref: kref for this channel.
* @rq_size: IB receive queue size.
* @max_rsp_size: Maximum size of an RSP response message in bytes.
@@ -276,6 +277,7 @@ struct srpt_rdma_ch {
struct ib_qp *qp;
struct ib_cq *cq;
struct ib_cqe zw_cqe;
+ struct rcu_head rcu;
struct kref kref;
int rq_size;
u32 max_rsp_size;