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    SubjectRe: [PATCH v2 13/24] drm/etnaviv: reject timeouts with tv_nsec >= NSEC_PER_SEC
    On Mon, Jan 20, 2020 at 6:48 PM Lucas Stach <l.stach@pengutronix.de> wrote:
    > On Fr, 2020-01-17 at 16:47 +0100, Guido Günther wrote:
    > >
    > > This breaks rendering here on arm64/gc7000 due to
    > >
    > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
    > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
    > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
    > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
    > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_PREP or DRM_IOCTL_MSM_GEM_CPU_PREP, 0xfffff7888680) = -1 EINVAL (Invalid argument)
    > > ioctl(6, DRM_IOCTL_ETNAVIV_GEM_CPU_FINI or DRM_IOCTL_QXL_CLIENTCAP, 0xfffff78885e0) = 0
    > >
    > > This is due to
    > >
    > > get_abs_timeout(&req.timeout, 5000000000);
    > >
    > > in etna_bo_cpu_prep which can exceed NSEC_PER_SEC.
    > >
    > > Should i send a patch to revert that change since it breaks existing userspace?
    >
    > No need to revert. This patch has not been applied to the etnaviv tree
    > yet, I guess it's just in one of Arnds branches feeding into -next.
    >
    > That part of userspace is pretty dumb, as it misses to renormalize
    > tv_nsec when it overflows the second boundary. So if what I see is
    > correct it should be enough to allow 2 * NSEC_PER_SEC, which should
    > both reject broken large timeout and keep existing userspace working.

    Ah, so it's never more than 2 billion nanoseconds in known user space?
    I can definitely change my patch (actually add one on top) to allow that
    and handle it as before, or alternatively accept any 64-bit nanosecond value
    as arm64 already did, but make it less inefficient to handle.

    Arnd

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