Applied. Thanks! On Sun, Oct 16, 2022 at 1:42 PM Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx> wrote: > > kmap() is being deprecated in favor of kmap_local_page(). > > There are two main problems with kmap(): (1) It comes with an overhead as > mapping space is restricted and protected by a global lock for > synchronization and (2) it also requires global TLB invalidation when the > kmap’s pool wraps and it might block when the mapping space is fully > utilized until a slot becomes available. > > With kmap_local_page() the mappings are per thread, CPU local, can take > page faults, and can be called from any context (including interrupts). > It is faster than kmap() in kernels with HIGHMEM enabled. Furthermore, > the tasks can be preempted and, when they are scheduled to run again, the > kernel virtual addresses are restored and are still valid. > > Since its use in amdgpu/amdgpu_ttm.c is safe, it should be preferred. > > Therefore, replace kmap() with kmap_local_page() in amdgpu/amdgpu_ttm.c. > > Suggested-by: Ira Weiny <ira.weiny@xxxxxxxxx> > Acked-by: Christian König <christian.koenig@xxxxxxx> > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@xxxxxxxxx> > --- > > I'm resending because I suspect that this patch might have been lost. In > the meantime I added an "Acked-by" tag from Christian K.. Obviviously, > there are no further changes in the code. > > drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > index 3b4c19412625..c11657b5915f 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > @@ -2301,9 +2301,9 @@ static ssize_t amdgpu_iomem_read(struct file *f, char __user *buf, > if (p->mapping != adev->mman.bdev.dev_mapping) > return -EPERM; > > - ptr = kmap(p); > + ptr = kmap_local_page(p); > r = copy_to_user(buf, ptr + off, bytes); > - kunmap(p); > + kunmap_local(ptr); > if (r) > return -EFAULT; > > @@ -2352,9 +2352,9 @@ static ssize_t amdgpu_iomem_write(struct file *f, const char __user *buf, > if (p->mapping != adev->mman.bdev.dev_mapping) > return -EPERM; > > - ptr = kmap(p); > + ptr = kmap_local_page(p); > r = copy_from_user(ptr + off, buf, bytes); > - kunmap(p); > + kunmap_local(ptr); > if (r) > return -EFAULT; > > -- > 2.37.1 >
