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    Subject[099/262] io-mapping: ensure io_mapping_map_atomic _is_ atomic
    3.0-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Daniel Vetter <daniel.vetter@ffwll.ch>

    commit 24dd85ff723f142093f44244764b9b5c152235b8 upstream.

    For the !HAVE_ATOMIC_IOMAP case the stub functions did not call
    pagefault_disable/_enable. The i915 driver relies on the map
    actually being atomic, otherwise it can deadlock with it's own
    pagefault handler in the gtt pwrite fastpath.

    This is exercised by gem_mmap_gtt from the intel-gpu-toosl gem
    testsuite.

    v2: Chris Wilson noted the lack of an include.

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=38115
    Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
    Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
    Signed-off-by: Keith Packard <keithp@keithp.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    include/linux/io-mapping.h | 4 ++++
    1 file changed, 4 insertions(+)

    --- a/include/linux/io-mapping.h
    +++ b/include/linux/io-mapping.h
    @@ -117,6 +117,8 @@ io_mapping_unmap(void __iomem *vaddr)

    #else

    +#include <linux/uaccess.h>
    +
    /* this struct isn't actually defined anywhere */
    struct io_mapping;

    @@ -138,12 +140,14 @@ static inline void __iomem *
    io_mapping_map_atomic_wc(struct io_mapping *mapping,
    unsigned long offset)
    {
    + pagefault_disable();
    return ((char __force __iomem *) mapping) + offset;
    }

    static inline void
    io_mapping_unmap_atomic(void __iomem *vaddr)
    {
    + pagefault_enable();
    }

    /* Non-atomic map/unmap */



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