On 2024/08/06 9:27, Rick Wertenbroek wrote:
> The test for a DMA transfer was done in pci_epf_test_cmd_handler, which
> if not supported would lead to the endpoint function just printing an
> error message and waiting for further commands. This would leave the
> host side PCI driver waiting for an interrupt because the call to
> pci_epf_test_raise_irq is skipped. The host side driver
> drivers/misc/pci_endpoint_test.c would hang indefinitely when sending
> a transfer request with DMA if the endpoint does not support it.
> This is because wait_for_completion() is used in the host side driver.
>
> Move the DMA check into the read/write/copy functions so that they
> report a transfer (IO) error so that pci_epf_test_raise_irq() is
> called when a transfer with DMA is requested, even if unsupported.
>
> The host side driver will still report an error on transfer thanks
> to the checksum, because no data was moved, but will not hang anymore
> waiting for an interrupt that will never arrive.
>
> Signed-off-by: Rick Wertenbroek <rick.wertenbroek@xxxxxxxxx>
> ---
> drivers/pci/endpoint/functions/pci-epf-test.c | 29 +++++++++++++++----
> 1 file changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 7c2ed6eae53a..bd4b37f46f41 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -314,6 +314,17 @@ static void pci_epf_test_print_rate(struct pci_epf_test *epf_test,
> (u64)ts.tv_sec, (u32)ts.tv_nsec, rate);
> }
>
> +static int pci_epf_test_check_dma(struct pci_epf_test *epf_test,
> + struct pci_epf_test_reg *reg)
> +{
> + if ((READ_ONCE(reg->flags) & FLAG_USE_DMA) &&
> + !epf_test->dma_supported) {
> + dev_err(&epf_test->epf->dev, "Cannot transfer data using DMA\n");
While at it, can we change this message to be clear, e.g. "DMA not supported".
"Cannot ..." is vague and does not state the reason why it cannot be done :)
> + return -EIO;
> + }
> + return 0;
> +}
> +
> static void pci_epf_test_copy(struct pci_epf_test *epf_test,
> struct pci_epf_test_reg *reg)
> {
> @@ -327,6 +338,10 @@ static void pci_epf_test_copy(struct pci_epf_test *epf_test,
> struct device *dev = &epf->dev;
> struct pci_epc *epc = epf->epc;
>
> + ret = pci_epf_test_check_dma(epf_test, reg);
> + if (ret)
> + goto err;
> +
> src_addr = pci_epc_mem_alloc_addr(epc, &src_phys_addr, reg->size);
> if (!src_addr) {
> dev_err(dev, "Failed to allocate source address\n");
> @@ -423,6 +438,10 @@ static void pci_epf_test_read(struct pci_epf_test *epf_test,
> struct pci_epc *epc = epf->epc;
> struct device *dma_dev = epf->epc->dev.parent;
>
> + ret = pci_epf_test_check_dma(epf_test, reg);
> + if (ret)
> + goto err;
> +
> src_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> if (!src_addr) {
> dev_err(dev, "Failed to allocate address\n");
> @@ -507,6 +526,10 @@ static void pci_epf_test_write(struct pci_epf_test *epf_test,
> struct pci_epc *epc = epf->epc;
> struct device *dma_dev = epf->epc->dev.parent;
>
> + ret = pci_epf_test_check_dma(epf_test, reg);
> + if (ret)
> + goto err;
> +
> dst_addr = pci_epc_mem_alloc_addr(epc, &phys_addr, reg->size);
> if (!dst_addr) {
> dev_err(dev, "Failed to allocate address\n");
> @@ -647,12 +670,6 @@ static void pci_epf_test_cmd_handler(struct work_struct *work)
> WRITE_ONCE(reg->command, 0);
> WRITE_ONCE(reg->status, 0);
>
> - if ((READ_ONCE(reg->flags) & FLAG_USE_DMA) &&
> - !epf_test->dma_supported) {
> - dev_err(dev, "Cannot transfer data using DMA\n");
> - goto reset_handler;
> - }
> -
> if (reg->irq_type > IRQ_TYPE_MSIX) {
> dev_err(dev, "Failed to detect IRQ type\n");
> goto reset_handler;
--
Damien Le Moal
Western Digital Research
