Re: [PATCH] linux/types.h: enable endian checks for all sparse builds

Madhani, Himanshu
2016-12-09T06:40:53Z

Hi Mike/Bart,

On 12/8/16, 8:17 AM, "virtualization-bounces@lists.linux-foundation.org on behalf of Michael S. Tsirkin" <virtualization-bounces@lists.linux-foundation.org on behalf of mst@redhat.com> wrote:

>On Thu, Dec 08, 2016 at 06:38:11AM +0000, Bart Van Assche wrote:
>> On 12/07/16 21:54, Michael S. Tsirkin wrote:
>> > On Thu, Dec 08, 2016 at 05:21:47AM +0000, Bart Van Assche wrote:
>> >> Additionally, there are notable exceptions to the rule that most drivers
>> >> are endian-clean, e.g. drivers/scsi/qla2xxx. I would appreciate it if it
>> >> would remain possible to check such drivers with sparse without enabling
>> >> endianness checks. Have you considered to change #ifdef __CHECK_ENDIAN__
>> >> into e.g. #ifndef __DONT_CHECK_ENDIAN__?
>> >
>> > The right thing is probably just to fix these, isn't it?
>> > Until then, why not just ignore the warnings?
>>
>> Neither option is realistic. With endian-checking enabled the qla2xxx
>> driver triggers so many warnings that it becomes a real challenge to
>> filter the non-endian warnings out manually:
>>
>> $ for f in "" CF=-D__CHECK_ENDIAN__; do make M=drivers/scsi/qla2xxx C=2\
>> $f | &grep -c ': warning:'; done
>> 4
>> 752
>
>You can always revert this patch in your tree, or whatever. It does not
>look like this will get fixed otherwise.
>
>> If you think it would be easy to fix the endian warnings triggered by
>> the qla2xxx driver, you are welcome to try to fix these.
>>
>> Bart.
>
>Yea, this hardware was designed by someone who thought mixing
>LE and BE all over the place is a good idea.
>But who said it should be easy?
>
>Maybe this change will be enough to motivate the maintainers.
>
>Here's a minor buglet for you as a motivator:
>
> if (ct_rsp->header.response !=
> cpu_to_be16(CT_ACCEPT_RESPONSE)) {
> ql_dbg(ql_dbg_disc + ql_dbg_buffer, vha, 0x2077,
> "%s failed rejected request on port_id: %02x%02x%02x Compeltion status 0x%x, response 0x%x\n",
> routine, vha->d_id.b.domain,
> vha->d_id.b.area, vha->d_id.b.al_pa, comp_status, ct_rsp->header.response);
>
>
>response is BE and isn't printed correctly.
>
>another:
>
> eiter->a.max_frame_size = cpu_to_be32(eiter->a.max_frame_size);
> size += 4 + 4;
>
> ql_dbg(ql_dbg_disc, vha, 0x20bc,
> "Max_Frame_Size = %x.\n", eiter->a.max_frame_size);
>
>printed too late, it's be by that time.
>
>Here's another suspicious line
>
> ctio24->u.status1.flags = (atio->u.isp24.attr << 9) |
> cpu_to_le16(CTIO7_FLAGS_STATUS_MODE_1 |
> CTIO7_FLAGS_TERMINATE);
>
>shifting attr by 9 bits gives different results on BE and LE,
>mixing it with le16 looks rather strange.
>
>Another:
>
> ha->flags.dport_enabled =
> (mid_init_cb->init_cb.firmware_options_1 & BIT_7) != 0;
>
>BIT_7 is native endian, firmware_options_1 is LE I think.
>
>
>
>Look at qla27xx_find_valid_image as well.
>
> if (pri_image_status.signature != QLA27XX_IMG_STATUS_SIGN)
>
>qla27xx_image_status seems to be data coming from flash, but is
>somehow native-endian? Maybe ...
>
>
> lun = a->u.isp24.fcp_cmnd.lun;
>
>I think lun here is in hardware format (le?), code treats it
>as native.
>
>
>Not to speak about interface abuse all over the place.
>How about this:
>
>uint32_t *
>qla24xx_read_flash_data(scsi_qla_host_t *vha, uint32_t *dwptr, uint32_t
>faddr,
> uint32_t dwords)
>{
> uint32_t i;
> struct qla_hw_data *ha = vha->hw;
>
> /* Dword reads to flash. */
> for (i = 0; i < dwords; i++, faddr++)
> dwptr[i] = cpu_to_le32(qla24xx_read_flash_dword(ha,
> flash_data_addr(ha, faddr)));
>
> return dwptr;
>}
>
>OK so we convert to LE ...
>
> qla24xx_read_flash_data(vha, dcode, faddr, 4);
>
> risc_addr = be32_to_cpu(dcode[2]);
> *srisc_addr = *srisc_addr == 0 ? risc_addr : *srisc_addr;
> risc_size = be32_to_cpu(dcode[3]);
>
>then happily assume it's BE.
>
>And again, coming from flash, it's unlikely to actually be in the native
>endian-ness as callers seem to assume. I'm guessing it's all BE.
>
>I poked at it a bit and was able to cut down # of warnings
>from 1700 to 1400 in an hour. Someone familiar with the code
>should look at it.

We’ll take a look and send patches to resolve these warnings.

>
>--
>MST
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