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SubjectRe: [PATCH v3] PCI: aardvark: Don't rely on jiffies while holding spinlock
On Fri, Sep 27, 2019 at 10:55:02AM +0200, Remi Pommarel wrote:
> advk_pcie_wait_pio() can be called while holding a spinlock (from
> pci_bus_read_config_dword()), then depends on jiffies in order to
> timeout while polling on PIO state registers. In the case the PIO
> transaction failed, the timeout will never happen and will also cause
> the cpu to stall.
>
> This decrements a variable and wait instead of using jiffies.
>
> Signed-off-by: Remi Pommarel <repk@triplefau.lt>
> ---
> Changes since v1:
> - Reduce polling delay
> - Change size_t into int for loop counter
> Changes since v2:
> - Keep timeout to 1ms by increasing retry counter
> ---
> drivers/pci/controller/pci-aardvark.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)

Applied to pci/aardvark, thanks.

Lorenzo

> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index fc0fe4d4de49..7b5c9d6c8706 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -175,7 +175,8 @@
> (PCIE_CONF_BUS(bus) | PCIE_CONF_DEV(PCI_SLOT(devfn)) | \
> PCIE_CONF_FUNC(PCI_FUNC(devfn)) | PCIE_CONF_REG(where))
>
> -#define PIO_TIMEOUT_MS 1
> +#define PIO_RETRY_CNT 500
> +#define PIO_RETRY_DELAY 2 /* 2 us*/
>
> #define LINK_WAIT_MAX_RETRIES 10
> #define LINK_WAIT_USLEEP_MIN 90000
> @@ -383,17 +384,16 @@ static void advk_pcie_check_pio_status(struct advk_pcie *pcie)
> static int advk_pcie_wait_pio(struct advk_pcie *pcie)
> {
> struct device *dev = &pcie->pdev->dev;
> - unsigned long timeout;
> + int i;
>
> - timeout = jiffies + msecs_to_jiffies(PIO_TIMEOUT_MS);
> -
> - while (time_before(jiffies, timeout)) {
> + for (i = 0; i < PIO_RETRY_CNT; i++) {
> u32 start, isr;
>
> start = advk_readl(pcie, PIO_START);
> isr = advk_readl(pcie, PIO_ISR);
> if (!start && isr)
> return 0;
> + udelay(PIO_RETRY_DELAY);
> }
>
> dev_err(dev, "config read/write timed out\n");
> --
> 2.20.1
>

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