drivers/scsi/libfc/fc_frame.c

   1 /*
   2  * Copyright(c) 2007 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  16  *
  17  * Maintained at www.Open-FCoE.org
  18  */
  19
  20 /*
  21  * Frame allocation.
  22  */
  23 #include <linux/module.h>
  24 #include <linux/kernel.h>
  25 #include <linux/skbuff.h>
  26 #include <linux/crc32.h>
  27 #include <linux/gfp.h>
  28
  29 #include <scsi/fc_frame.h>
  30
  31 /*
  32  * Check the CRC in a frame.
  33  */
  34 u32 fc_frame_crc_check(struct fc_frame *fp)
  35 {
  36         u32 crc;
  37         u32 error;
  38         const u8 *bp;
  39         unsigned int len;
  40
  41         WARN_ON(!fc_frame_is_linear(fp));
  42         fr_flags(fp) &= ~FCPHF_CRC_UNCHECKED;
  43         len = (fr_len(fp) + 3) & ~3;    /* round up length to include fill */
  44         bp = (const u8 *) fr_hdr(fp);
  45         crc = ~crc32(~0, bp, len);
  46         error = crc ^ fr_crc(fp);
  47         return error;
  48 }
  49 EXPORT_SYMBOL(fc_frame_crc_check);
  50
  51 /*
  52  * Allocate a frame intended to be sent.
  53  * Get an sk_buff for the frame and set the length.
  54  */
  55 struct fc_frame *_fc_frame_alloc(size_t len)
  56 {
  57         struct fc_frame *fp;
  58         struct sk_buff *skb;
  59
  60         WARN_ON((len % sizeof(u32)) != 0);
  61         len += sizeof(struct fc_frame_header);
  62         skb = alloc_skb_fclone(len + FC_FRAME_HEADROOM + FC_FRAME_TAILROOM +
  63                                NET_SKB_PAD, GFP_ATOMIC);
  64         if (!skb)
  65                 return NULL;
  66         skb_reserve(skb, NET_SKB_PAD + FC_FRAME_HEADROOM);
  67         fp = (struct fc_frame *) skb;
  68         fc_frame_init(fp);
  69         skb_put(skb, len);
  70         return fp;
  71 }
  72 EXPORT_SYMBOL(_fc_frame_alloc);
  73
  74 struct fc_frame *fc_frame_alloc_fill(struct fc_lport *lp, size_t payload_len)
  75 {
  76         struct fc_frame *fp;
  77         size_t fill;
  78
  79         fill = payload_len % 4;
  80         if (fill != 0)
  81                 fill = 4 - fill;
  82         fp = _fc_frame_alloc(payload_len + fill);
  83         if (fp) {
  84                 memset((char *) fr_hdr(fp) + payload_len, 0, fill);
  85                 /* trim is OK, we just allocated it so there are no fragments */
  86                 skb_trim(fp_skb(fp),
  87                          payload_len + sizeof(struct fc_frame_header));
  88         }
  89         return fp;
  90 }
  91 EXPORT_SYMBOL(fc_frame_alloc_fill);