[efi] Provide guaranteed space in transmitted packets

eIPoIB requires space to expand a transmitted ARP packet.  This
guarantee is met by ensuring that a transmitted packet consists of at
least MAX_LL_HEADER_LEN bytes from the start of the I/O buffer up to
the end of the link-layer header, and at least IOB_ZLEN bytes
thereafter.

Adjust the I/O buffer allocation for SNP transmitted packets to ensure
that this guarantee is met.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/interface/efi/efi_snp.c b/src/interface/efi/efi_snp.c
index 6d7865dd2a279d5a2ada3bafc1fcf340d3a60c28..b4ae5113d82e4bfb20faa9d341cba84a620c3400 100644 (file)
--- a/src/interface/efi/efi_snp.c
+++ b/src/interface/efi/efi_snp.c
@@ -536,7 +536,7 @@ efi_snp_transmit ( EFI_SIMPLE_NETWORK_PROTOCOL *snp,
                container_of ( snp, struct efi_snp_device, snp );
        struct ll_protocol *ll_protocol = snpdev->netdev->ll_protocol;
        struct io_buffer *iobuf;
-       size_t ll_headroom;
+       size_t payload_len;
        int rc;
        EFI_STATUS efirc;
 
@@ -589,21 +589,22 @@ efi_snp_transmit ( EFI_SIMPLE_NETWORK_PROTOCOL *snp,
        }
 
        /* Allocate buffer */
-       ll_headroom = ( MAX_LL_HEADER_LEN - ll_header_len );
-       iobuf = alloc_iob ( ll_headroom +
-                           ( ( len > IOB_ZLEN ) ? len : IOB_ZLEN ) );
+       payload_len = ( len - ll_protocol->ll_header_len );
+       iobuf = alloc_iob ( MAX_LL_HEADER_LEN + ( ( payload_len > IOB_ZLEN ) ?
+                                                 payload_len : IOB_ZLEN ) );
        if ( ! iobuf ) {
                DBGC ( snpdev, "SNPDEV %p TX could not allocate %ld-byte "
                       "buffer\n", snpdev, ( ( unsigned long ) len ) );
                efirc = EFI_DEVICE_ERROR;
                goto err_alloc_iob;
        }
-       iob_reserve ( iobuf, ll_headroom );
+       iob_reserve ( iobuf, ( MAX_LL_HEADER_LEN -
+                              ll_protocol->ll_header_len ) );
        memcpy ( iob_put ( iobuf, len ), data, len );
 
        /* Create link-layer header, if specified */
        if ( ll_header_len ) {
-               iob_pull ( iobuf, ll_header_len );
+               iob_pull ( iobuf, ll_protocol->ll_header_len );
                if ( ( rc = ll_protocol->push ( snpdev->netdev,
                                                iobuf, ll_dest, ll_src,
                                                htons ( *net_proto ) )) != 0 ){