diff options
| author | Zhao Liu <zhao1.liu@intel.com> | 2023-12-03 21:29:41 +0800 |
|---|---|---|
| committer | Tvrtko Ursulin <tvrtko.ursulin@intel.com> | 2023-12-15 09:34:28 +0000 |
| commit | 756eed0f2602f73df8d6c5bc8418ecd11cce9803 (patch) | |
| tree | 91be7e8f76412d1303d69f07bed3bc0ecc206154 /drivers/gpu/drm/i915 | |
| parent | f4d88908cd9a430a7473eea6ff2300a3b728e11c (diff) | |
drm/i915: Use kmap_local_page() in gem/i915_gem_shmem.c
The use of kmap_atomic() is being deprecated in favor of
kmap_local_page()[1].
The main difference between atomic and local mappings is that local
mappings doesn't disable page faults or preemption (the preemption is
disabled for !PREEMPT_RT case, otherwise it only disables migration).
With kmap_local_page(), we can avoid the often unwanted side effect of
unnecessary page faults or preemption disables.
In drm/i915/gem/i915_gem_shmem.c, the function shmem_pwrite() need to
disable pagefault to eliminate the potential recursion fault[2]. But
here __copy_from_user_inatomic() doesn't need to disable preemption and
local mapping is valid for sched in/out.
So it can use kmap_local_page() / kunmap_local() with
pagefault_disable() / pagefault_enable() to replace atomic mapping.
[1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com
[2]: https://patchwork.freedesktop.org/patch/295840/
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231203132947.2328805-4-zhao1.liu@linux.intel.com
Diffstat (limited to 'drivers/gpu/drm/i915')
| -rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c index 73a4a4eb29e0..38b72d86560f 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -485,11 +485,13 @@ shmem_pwrite(struct drm_i915_gem_object *obj, if (err < 0) return err; - vaddr = kmap_atomic(page); + vaddr = kmap_local_page(page); + pagefault_disable(); unwritten = __copy_from_user_inatomic(vaddr + pg, user_data, len); - kunmap_atomic(vaddr); + pagefault_enable(); + kunmap_local(vaddr); err = aops->write_end(obj->base.filp, mapping, offset, len, len - unwritten, page, data); |