WARNING: drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:364 vchiq_prepare_bulk_data

[Stefan Wahren]

Hi Arnd,

Am 11.06.24 um 14:14 schrieb Arnd Bergmann:
> On Tue, Jun 11, 2024, at 13:37, Stefan Wahren wrote:
>> Am 11.06.24 um 13:08 schrieb Arnd Bergmann:
>>> On Tue, Jun 11, 2024, at 12:47, Stefan Wahren wrote:
>>           if (len == 0)
>>               pr_warn_once("%s: sg_dma_len() == 0\n", __func__);
>>           else if (i && (i != (dma_buffers - 1)) && (len & ~PAGE_MASK))
>>               pr_warn_once("%s: following block not page aligned\n",
>> __func__);
>>           else if (i && (addr & ~PAGE_MASK)) {
>>               pr_warn_once("%s: block %u, DMA address %pad doesn't align
>> with PAGE_MASK 0x%lx\n", __func__, i, &addr, PAGE_MASK);
>>               pr_warn_once("sg_dma_is_swiotlb: %d, dma_flags: %x\n",
>> sg_dma_is_swiotlb(sg), sg->dma_flags);
>>               pr_warn_once("type = %s\n", (type == PAGELIST_WRITE) ?
>> "PAGELIST_WRITE" : "PAGELIST_READ");
>>               if (buf)
>>                   pr_warn_once("buf = %p, count = %zu\n", buf, count);
>>               else
>>                   pr_warn_once("ubuf = %p, count = %zu\n", ubuf, count);
>>           }
>>
>> Output:
>>
>> [   66.184030] create_pagelist: block 1, DMA address 0x00000000f5fc7800
>> doesn't align with PAGE_MASK 0xfffffffffffff000
>> [   66.184056] sg_dma_is_swiotlb: 0, dma_flags: 0
>> [   66.184063] type = PAGELIST_READ
>> [   66.184066] ubuf = 00000000266a70a7, count = 0
sorry my debug attempt for count was pointless. The value is always
decremented to zero at this point. So your suggested change won't have
any effect.
>  From my reading of the code, it's not really meant to handle
> count=0, so maybe the answer for that is to just return an
> error (or possibly success) when there is data attached to
> the request from user space, something like
>
> --- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev.c
> +++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev.c
> @@ -328,6 +328,11 @@ static int vchiq_irq_queue_bulk_tx_rx(struct vchiq_instance *instance,
>                  userdata = args->userdata;
>          }
>
> +       if (!args->size) {
> +               ret = 0;
> +               goto out;
> +       }
> +
>          status = vchiq_bulk_transfer(instance, args->handle, NULL, args->data, args->size,
>                                       userdata, args->mode, dir);
>
>
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