drivers/scsi/libfc/fc_frame.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright(c) 2007 Intel Corporation. All rights reserved.
   4  *
   5  * Maintained at www.Open-FCoE.org
   6  */
   7
   8 /*
   9  * Frame allocation.
  10  */
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/crc32.h>
  15 #include <linux/gfp.h>
  16
  17 #include <scsi/fc_frame.h>
  18
  19 /*
  20  * Check the CRC in a frame.
  21  */
  22 u32 fc_frame_crc_check(struct fc_frame *fp)
  23 {
  24         u32 crc;
  25         u32 error;
  26         const u8 *bp;
  27         unsigned int len;
  28
  29         WARN_ON(!fc_frame_is_linear(fp));
  30         fr_flags(fp) &= ~FCPHF_CRC_UNCHECKED;
  31         len = (fr_len(fp) + 3) & ~3;    /* round up length to include fill */
  32         bp = (const u8 *) fr_hdr(fp);
  33         crc = ~crc32(~0, bp, len);
  34         error = crc ^ fr_crc(fp);
  35         return error;
  36 }
  37 EXPORT_SYMBOL(fc_frame_crc_check);
  38
  39 /*
  40  * Allocate a frame intended to be sent.
  41  * Get an sk_buff for the frame and set the length.
  42  */
  43 struct fc_frame *_fc_frame_alloc(size_t len)
  44 {
  45         struct fc_frame *fp;
  46         struct sk_buff *skb;
  47
  48         WARN_ON((len % sizeof(u32)) != 0);
  49         len += sizeof(struct fc_frame_header);
  50         skb = alloc_skb_fclone(len + FC_FRAME_HEADROOM + FC_FRAME_TAILROOM +
  51                                NET_SKB_PAD, GFP_ATOMIC);
  52         if (!skb)
  53                 return NULL;
  54         skb_reserve(skb, NET_SKB_PAD + FC_FRAME_HEADROOM);
  55         fp = (struct fc_frame *) skb;
  56         fc_frame_init(fp);
  57         skb_put(skb, len);
  58         return fp;
  59 }
  60 EXPORT_SYMBOL(_fc_frame_alloc);
  61
  62 struct fc_frame *fc_frame_alloc_fill(struct fc_lport *lp, size_t payload_len)
  63 {
  64         struct fc_frame *fp;
  65         size_t fill;
  66
  67         fill = payload_len % 4;
  68         if (fill != 0)
  69                 fill = 4 - fill;
  70         fp = _fc_frame_alloc(payload_len + fill);
  71         if (fp) {
  72                 memset((char *) fr_hdr(fp) + payload_len, 0, fill);
  73                 /* trim is OK, we just allocated it so there are no fragments */
  74                 skb_trim(fp_skb(fp),
  75                          payload_len + sizeof(struct fc_frame_header));
  76         }
  77         return fp;
  78 }
  79 EXPORT_SYMBOL(fc_frame_alloc_fill);