RDMA/iw_cxgb4: Low resource fixes for Completion queue

Pre-allocate buffers to deallocate completion queue, so that completion
queue is deallocated during RDMA termination when system is running
out of memory.

Signed-off-by: Steve Wise <[e-mail]>
Signed-off-by: Hariprasad Shenai <[e-mail]>
Signed-off-by: Doug Ledford <[e-mail]>

drivers/infiniband/hw/cxgb4/cq.c

···
 #include "iw_cxgb4.h"
 
 static int destroy_cq(struct c4iw_rdev *rdev, struct t4_cq *cq,
-		      struct c4iw_dev_ucontext *uctx)
+		      struct c4iw_dev_ucontext *uctx, struct sk_buff *skb)
 {
 	struct fw_ri_res_wr *res_wr;
 	struct fw_ri_res *res;
 	int wr_len;
 	struct c4iw_wr_wait wr_wait;
-	struct sk_buff *skb;
 	int ret;
 
 	wr_len = sizeof *res_wr + sizeof *res;
-	skb = alloc_skb(wr_len, GFP_KERNEL);
-	if (!skb)
-		return -ENOMEM;
 	set_wr_txq(skb, CPL_PRIORITY_CONTROL, 0);
 
 	res_wr = (struct fw_ri_res_wr *)__skb_put(skb, wr_len);
···
 	ucontext = ib_cq->uobject ? to_c4iw_ucontext(ib_cq->uobject->context)
 				  : NULL;
 	destroy_cq(&chp->rhp->rdev, &chp->cq,
-		   ucontext ? &ucontext->uctx : &chp->cq.rdev->uctx);
+		   ucontext ? &ucontext->uctx : &chp->cq.rdev->uctx,
+		   chp->destroy_skb);
+	chp->destroy_skb = NULL;
 	kfree(chp);
 	return 0;
 }
···
 	struct c4iw_cq *chp;
 	struct c4iw_create_cq_resp uresp;
 	struct c4iw_ucontext *ucontext = NULL;
-	int ret;
+	int ret, wr_len;
 	size_t memsize, hwentries;
 	struct c4iw_mm_entry *mm, *mm2;
 
···
 	chp = kzalloc(sizeof(*chp), GFP_KERNEL);
 	if (!chp)
 		return ERR_PTR(-ENOMEM);
+
+	wr_len = sizeof(struct fw_ri_res_wr) + sizeof(struct fw_ri_res);
+	chp->destroy_skb = alloc_skb(wr_len, GFP_KERNEL);
+	if (!chp->destroy_skb) {
+		ret = -ENOMEM;
+		goto err1;
+	}
 
 	if (ib_context)
 		ucontext = to_c4iw_ucontext(ib_context);
···
 	ret = create_cq(&rhp->rdev, &chp->cq,
 			ucontext ? &ucontext->uctx : &rhp->rdev.uctx);
 	if (ret)
-		goto err1;
+		goto err2;
 
 	chp->rhp = rhp;
 	chp->cq.size--;				/* status page */
···
 	init_waitqueue_head(&chp->wait);
 	ret = insert_handle(rhp, &rhp->cqidr, chp, chp->cq.cqid);
 	if (ret)
-		goto err2;
+		goto err3;
 
 	if (ucontext) {
 		mm = kmalloc(sizeof *mm, GFP_KERNEL);
 		if (!mm)
-			goto err3;
+			goto err4;
 		mm2 = kmalloc(sizeof *mm2, GFP_KERNEL);
 		if (!mm2)
-			goto err4;
+			goto err5;
 
 		uresp.qid_mask = rhp->rdev.cqmask;
 		uresp.cqid = chp->cq.cqid;
···
 		ret = ib_copy_to_udata(udata, &uresp,
 				       sizeof(uresp) - sizeof(uresp.reserved));
 		if (ret)
-			goto err5;
+			goto err6;
 
 		mm->key = uresp.key;
 		mm->addr = virt_to_phys(chp->cq.queue);
···
 	     __func__, chp->cq.cqid, chp, chp->cq.size,
 	     chp->cq.memsize, (unsigned long long) chp->cq.dma_addr);
 	return &chp->ibcq;
-err5:
+err6:
 	kfree(mm2);
-err4:
+err5:
 	kfree(mm);
-err3:
+err4:
 	remove_handle(rhp, &rhp->cqidr, chp->cq.cqid);
-err2:
+err3:
 	destroy_cq(&chp->rhp->rdev, &chp->cq,
-		   ucontext ? &ucontext->uctx : &rhp->rdev.uctx);
+		   ucontext ? &ucontext->uctx : &rhp->rdev.uctx,
+		   chp->destroy_skb);
+err2:
+	kfree_skb(chp->destroy_skb);
 err1:
 	kfree(chp);
 	return ERR_PTR(ret);

drivers/infiniband/hw/cxgb4/iw_cxgb4.h

···
 struct c4iw_cq {
 	struct ib_cq ibcq;
 	struct c4iw_dev *rhp;
+	struct sk_buff *destroy_skb;
 	struct t4_cq cq;
 	spinlock_t lock;
 	spinlock_t comp_handler_lock;