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| author | Loïc Molinari <loic.molinari@collabora.com> | 2025-12-05 21:22:22 +0300 |
|---|---|---|
| committer | Boris Brezillon <boris.brezillon@collabora.com> | 2025-12-08 12:52:47 +0300 |
| commit | 9d2d49027c3a9628989c9ec70ebef9d241f49c1e (patch) | |
| tree | 331a89812ab2ce75bb5022e6905b63b5adae9971 | |
| parent | d8f94cb02af3cc64013373c94a4b7780782ea59c (diff) | |
| download | linux-9d2d49027c3a9628989c9ec70ebef9d241f49c1e.tar.xz | |
drm/shmem-helper: Simplify page offset calculation in fault handler
For a fault at address addr, the page offset is
page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT
= ((addr & PAGE_MASK) - vma->vm_start) >> PAGE_SHIFT
= (addr - vma->vm_start) >> PAGE_SHIFT
Since the faulty logical page offset based on VMA is
vmf->pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
We can slightly simplify the calculation using
page_offset = vmf->pgoff - vma->vm_pgoff
v11:
- remove misleading comment
- add Boris R-b
Signed-off-by: Loïc Molinari <loic.molinari@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://patch.msgid.link/20251205182231.194072-2-loic.molinari@collabora.com
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
| -rw-r--r-- | drivers/gpu/drm/drm_gem_shmem_helper.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index dc94a27710e5..e47ab3ebb5c2 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -577,8 +577,8 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) struct page *page; pgoff_t page_offset; - /* We don't use vmf->pgoff since that has the fake offset */ - page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT; + /* Offset to faulty address in the VMA. */ + page_offset = vmf->pgoff - vma->vm_pgoff; dma_resv_lock(shmem->base.resv, NULL); |