// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright(c) 2007 Intel Corporation. All rights reserved.
 *
 * Maintained at www.Open-FCoE.org
 */

/*
 * Frame allocation.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/crc32.h>
#include <linux/gfp.h>

#include <scsi/fc_frame.h>

/*
 * Check the CRC in a frame.
 */
u32 fc_frame_crc_check(struct fc_frame *fp)
{
        u32 crc;
        u32 error;
        const u8 *bp;
        unsigned int len;

        WARN_ON(!fc_frame_is_linear(fp));
        fr_flags(fp) &= ~FCPHF_CRC_UNCHECKED;
        len = (fr_len(fp) + 3) & ~3;    /* round up length to include fill */
        bp = (const u8 *) fr_hdr(fp);
        crc = ~crc32(~0, bp, len);
        error = crc ^ fr_crc(fp);
        return error;
}
EXPORT_SYMBOL(fc_frame_crc_check);

/*
 * Allocate a frame intended to be sent.
 * Get an sk_buff for the frame and set the length.
 */
struct fc_frame *_fc_frame_alloc(size_t len)
{
        struct fc_frame *fp;
        struct sk_buff *skb;

        WARN_ON((len % sizeof(u32)) != 0);
        len += sizeof(struct fc_frame_header);
        skb = alloc_skb_fclone(len + FC_FRAME_HEADROOM + FC_FRAME_TAILROOM +
                               NET_SKB_PAD, GFP_ATOMIC);
        if (!skb)
                return NULL;
        skb_reserve(skb, NET_SKB_PAD + FC_FRAME_HEADROOM);
        fp = (struct fc_frame *) skb;
        fc_frame_init(fp);
        skb_put(skb, len);
        return fp;
}
EXPORT_SYMBOL(_fc_frame_alloc);

struct fc_frame *fc_frame_alloc_fill(struct fc_lport *lp, size_t payload_len)
{
        struct fc_frame *fp;
        size_t fill;

        fill = payload_len % 4;
        if (fill != 0)
                fill = 4 - fill;
        fp = _fc_frame_alloc(payload_len + fill);
        if (fp) {
                memset((char *) fr_hdr(fp) + payload_len, 0, fill);
                /* trim is OK, we just allocated it so there are no fragments */
                skb_trim(fp_skb(fp),
                         payload_len + sizeof(struct fc_frame_header));
        }
        return fp;
}
EXPORT_SYMBOL(fc_frame_alloc_fill);