kbev_cqueue.c

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/* -*- C -*- */
/*
 * Copyright (c) 2012-2020 Seagate Technology LLC and/or its Affiliates
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */


#include <linux/highmem.h>      /* kmap_atomic */

static struct nlx_core_bev_link *bev_cqueue_pnext(
                                           const struct nlx_core_bev_cqueue *q)
{
        struct nlx_core_bev_link *p;
        const struct nlx_core_kmem_loc *loc;
        char *ptr;

        M0_PRE(bev_cqueue_invariant(q));
        loc = &q->cbcq_producer_loc;
        M0_PRE(nlx_core_kmem_loc_invariant(loc) && _0C(loc->kl_page != NULL));
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0)
        ptr = kmap_atomic(loc->kl_page);
#else
        ptr = kmap_atomic(loc->kl_page, KM_USER1);
#endif
        p = (struct nlx_core_bev_link *) (ptr + loc->kl_offset);
        M0_POST(nlx_core_kmem_loc_invariant(&p->cbl_p_self_loc));
        M0_POST(p->cbl_c_self != q->cbcq_consumer);
        return p;
}

static void bev_cqueue_put(struct nlx_core_bev_cqueue *q,
                           struct nlx_core_bev_link *p)
{

        M0_PRE(bev_cqueue_invariant(q));
        M0_PRE(p->cbl_c_self != q->cbcq_consumer);
        M0_PRE(nlx_core_kmem_loc_eq(&q->cbcq_producer_loc, &p->cbl_p_self_loc));
        q->cbcq_producer_loc = p->cbl_p_next_loc;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(3,10,0)
        kunmap_atomic(p);
#else
        kunmap_atomic(p, KM_USER1);
#endif
        m0_atomic64_inc(&q->cbcq_count);
}

static void bev_link_bless(struct nlx_core_bev_link *ql, struct page *pg)
{
        nlx_core_kmem_loc_set(&ql->cbl_p_self_loc,
                              pg, NLX_PAGE_OFFSET((unsigned long) ql));
}
 /* bevcqueue */

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 80
 *  scroll-step: 1
 *  End:
 */