usbip tools from 5.4 fail to build due to unaligned pointer value warning

[Vadim Troshchinskiy <vtroshchinskiy@qindel.com>]

Hello,

Building the usbip tools from 4.15 is failing under Fedora 30, gcc version 
9.2.1:



$ make                                                                                                                                                                                                                                                                          
make  all-recursive
make[1]: Entering directory '/home/vadim/git/linux-orig/tools/usb/usbip'
Making all in libsrc
make[2]: Entering directory '/home/vadim/git/linux-orig/tools/usb/usbip/
libsrc'
make[2]: Nothing to be done for 'all'.
make[2]: Leaving directory '/home/vadim/git/linux-orig/tools/usb/usbip/libsrc'
Making all in src
make[2]: Entering directory '/home/vadim/git/linux-orig/tools/usb/usbip/src'
  CC       usbip_network.o
usbip_network.c: In function ‘usbip_net_pack_usb_device’:
usbip_network.c:79:32: error: taking address of packed member of ‘struct 
usbip_usb_device’ may result in an unaligned pointer value [-Werror=address-
of-packed-member]
   79 |  usbip_net_pack_uint32_t(pack, &udev->busnum);
      |                                ^~~~~~~~~~~~~
usbip_network.c:80:32: error: taking address of packed member of ‘struct 
usbip_usb_device’ may result in an unaligned pointer value [-Werror=address-
of-packed-member]
   80 |  usbip_net_pack_uint32_t(pack, &udev->devnum);
      |                                ^~~~~~~~~~~~~
usbip_network.c:81:32: error: taking address of packed member of ‘struct 
usbip_usb_device’ may result in an unaligned pointer value [-Werror=address-
of-packed-member]
   81 |  usbip_net_pack_uint32_t(pack, &udev->speed);
      |                                ^~~~~~~~~~~~
usbip_network.c:83:32: error: taking address of packed member of ‘struct 
usbip_usb_device’ may result in an unaligned pointer value [-Werror=address-
of-packed-member]
   83 |  usbip_net_pack_uint16_t(pack, &udev->idVendor);
      |                                ^~~~~~~~~~~~~~~
usbip_network.c:84:32: error: taking address of packed member of ‘struct 
usbip_usb_device’ may result in an unaligned pointer value [-Werror=address-
of-packed-member]
   84 |  usbip_net_pack_uint16_t(pack, &udev->idProduct);
      |                                ^~~~~~~~~~~~~~~~
usbip_network.c:85:32: error: taking address of packed member of ‘struct 
usbip_usb_device’ may result in an unaligned pointer value [-Werror=address-
of-packed-member]
   85 |  usbip_net_pack_uint16_t(pack, &udev->bcdDevice);
      |                                ^~~~~~~~~~~~~~~~
In file included from usbip_network.c:21:
usbip_network.c: In function ‘usbip_net_send_op_common’:
usbip_network.h:36:32: error: taking address of packed member of ‘struct 
op_common’ may result in an unaligned pointer value [-Werror=address-of-
packed-member]
   36 |  usbip_net_pack_uint16_t(pack, &(op_common)->version);\
      |                                ^~~~~~~~~~~~~~~~~~~~~
usbip_network.c:143:2: note: in expansion of macro ‘PACK_OP_COMMON’
  143 |  PACK_OP_COMMON(1, &op_common);
      |  ^~~~~~~~~~~~~~
usbip_network.h:37:32: error: taking address of packed member of ‘struct 
op_common’ may result in an unaligned pointer value [-Werror=address-of-
packed-member]
   37 |  usbip_net_pack_uint16_t(pack, &(op_common)->code);\
      |                                ^~~~~~~~~~~~~~~~~~
usbip_network.c:143:2: note: in expansion of macro ‘PACK_OP_COMMON’
  143 |  PACK_OP_COMMON(1, &op_common);
      |  ^~~~~~~~~~~~~~
usbip_network.h:38:32: error: taking address of packed member of ‘struct 
op_common’ may result in an unaligned pointer value [-Werror=address-of-
packed-member]
   38 |  usbip_net_pack_uint32_t(pack, &(op_common)->status);\
      |                                ^~~~~~~~~~~~~~~~~~~~
usbip_network.c:143:2: note: in expansion of macro ‘PACK_OP_COMMON’
  143 |  PACK_OP_COMMON(1, &op_common);
      |  ^~~~~~~~~~~~~~
usbip_network.c: In function ‘usbip_net_recv_op_common’:
usbip_network.h:36:32: error: taking address of packed member of ‘struct 
op_common’ may result in an unaligned pointer value [-Werror=address-of-
packed-member]
   36 |  usbip_net_pack_uint16_t(pack, &(op_common)->version);\
      |                                ^~~~~~~~~~~~~~~~~~~~~
usbip_network.c:167:2: note: in expansion of macro ‘PACK_OP_COMMON’
  167 |  PACK_OP_COMMON(0, &op_common);
      |  ^~~~~~~~~~~~~~
usbip_network.h:37:32: error: taking address of packed member of ‘struct 
op_common’ may result in an unaligned pointer value [-Werror=address-of-
packed-member]
   37 |  usbip_net_pack_uint16_t(pack, &(op_common)->code);\
      |                                ^~~~~~~~~~~~~~~~~~
usbip_network.c:167:2: note: in expansion of macro ‘PACK_OP_COMMON’
  167 |  PACK_OP_COMMON(0, &op_common);
      |  ^~~~~~~~~~~~~~
usbip_network.h:38:32: error: taking address of packed member of ‘struct 
op_common’ may result in an unaligned pointer value [-Werror=address-of-
packed-member]
   38 |  usbip_net_pack_uint32_t(pack, &(op_common)->status);\
      |                                ^~~~~~~~~~~~~~~~~~~~
usbip_network.c:167:2: note: in expansion of macro ‘PACK_OP_COMMON’
  167 |  PACK_OP_COMMON(0, &op_common);
      |  ^~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[2]: *** [Makefile:430: usbip_network.o] Error 1
make[2]: Leaving directory '/home/vadim/git/linux-orig/tools/usb/usbip/src'
make[1]: *** [Makefile:497: all-recursive] Error 1
make[1]: Leaving directory '/home/vadim/git/linux-orig/tools/usb/usbip'
make: *** [Makefile:365: all] Error 2

It looks like this is due to gcc having added new warnings. For now I've 
worked around it with -Wno-error=address-of-packed-member as I understand this 
isn't a problem on x86.