[Linaro-mm-sig] Re: [PATCH v8 7/7] rust: drm/gem: Add vmap functions to shmem bindings

On Wed, 2026-03-11 at 15:52 -0400, Lyude Paul wrote:

• /// Attempt to create a [`RawIoSysMap`] from the gem object.
• fn raw_vmap(&self) -> Result<*mut c_void> {

•    let mut map: MaybeUninit<bindings::iosys_map> = MaybeUninit::uninit();
  

•    // SAFETY: drm_gem_shmem_vmap can be called with the DMA reservation lock held
  

•    to_result(unsafe {
  

•        // TODO: see top of file
  

•        bindings::dma_resv_lock(self.raw_dma_resv(), ptr::null_mut());
  

•        let ret = bindings::drm_gem_shmem_vmap_locked(self.as_raw_shmem(), map.as_mut_ptr());
  

•        bindings::dma_resv_unlock(self.raw_dma_resv());
  

•        ret
  

•    })?;
  

•    // SAFETY: The call to drm_gem_shmem_vunmap_locked succeeded above, so we are guaranteed
  

•    // that map is properly initialized.
  

•    let map = unsafe { map.assume_init() };
  

•    // XXX: We don't currently support iomem allocations
  

•    if map.is_iomem {
  

•        // SAFETY:
  

•        // - The vmap operation above succeeded, making it safe to call vunmap
  

•        // - We checked that this is an iomem allocation, making it safe to read vaddr_iomem
  

•        unsafe { self.raw_vunmap(map.__bindgen_anon_1.vaddr_iomem) };
  

•        Err(ENOTSUPP)
  

•    } else {
  

•        // SAFETY: We checked that this is not an iomem allocation, making it safe to read vaddr
  

•        Ok(unsafe { map.__bindgen_anon_1.vaddr })
  

•    }
  

• }

I am missing a size check here to confirm that SIZE is valid, whoops. Will fix in the next version (though, hopefully that will be the final one)