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Message-Id: <20201012085203.56119-2-christian.koenig@amd.com>
Date: Mon, 12 Oct 2020 10:52:03 +0200
From: "Christian König"
<ckoenig.leichtzumerken@...il.com>
To: akpm@...ux-foundation.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, linaro-mm-sig@...ts.linaro.org,
dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
chris@...is-wilson.co.uk, airlied@...hat.com, daniel@...ll.ch,
sumit.semwal@...aro.org, willy@...radead.org, jhubbard@...dia.com,
jgg@...pe.ca, linmiaohe@...wei.com
Subject: [PATCH 2/2] mm: introduce vma_set_file function v4
Add the new vma_set_file() function to allow changing
vma->vm_file with the necessary refcount dance.
v2: add more users of this.
v3: add missing EXPORT_SYMBOL, rebase on mmap cleanup,
add comments why we drop the reference on two occasions.
v4: make it clear that changing an anonymous vma is illegal.
Signed-off-by: Christian König <christian.koenig@....com>
Reviewed-by: Daniel Vetter <daniel.vetter@...ll.ch> (v2)
---
drivers/dma-buf/dma-buf.c | 3 +--
drivers/gpu/drm/etnaviv/etnaviv_gem.c | 4 +---
drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 3 +--
drivers/gpu/drm/i915/gem/i915_gem_mman.c | 5 +++--
drivers/gpu/drm/msm/msm_gem.c | 4 +---
drivers/gpu/drm/omapdrm/omap_gem.c | 3 +--
drivers/gpu/drm/vgem/vgem_drv.c | 3 +--
drivers/staging/android/ashmem.c | 6 +++---
include/linux/mm.h | 2 ++
mm/mmap.c | 12 ++++++++++++
10 files changed, 26 insertions(+), 19 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 08630d057cf2..8e6a114c6034 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1160,8 +1160,7 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
return -EINVAL;
/* readjust the vma */
- fput(vma->vm_file);
- vma->vm_file = get_file(dmabuf->file);
+ vma_set_file(vma, dmabuf->file);
vma->vm_pgoff = pgoff;
return dmabuf->ops->mmap(dmabuf, vma);
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
index 312e9d58d5a7..10ce267c0947 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
@@ -145,10 +145,8 @@ static int etnaviv_gem_mmap_obj(struct etnaviv_gem_object *etnaviv_obj,
* address_space (so unmap_mapping_range does what we want,
* in particular in the case of mmap'd dmabufs)
*/
- fput(vma->vm_file);
- get_file(etnaviv_obj->base.filp);
vma->vm_pgoff = 0;
- vma->vm_file = etnaviv_obj->base.filp;
+ vma_set_file(vma, etnaviv_obj->base.filp);
vma->vm_page_prot = vm_page_prot;
}
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index fec0e1e3dc3e..8ce4c9e28b87 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -119,8 +119,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *
if (ret)
return ret;
- fput(vma->vm_file);
- vma->vm_file = get_file(obj->base.filp);
+ vma_set_file(vma, obj->base.filp);
return 0;
}
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index 3d69e51f3e4d..ec28a6cde49b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -893,8 +893,9 @@ int i915_gem_mmap(struct file *filp, struct vm_area_struct *vma)
* requires avoiding extraneous references to their filp, hence why
* we prefer to use an anonymous file for their mmaps.
*/
- fput(vma->vm_file);
- vma->vm_file = anon;
+ vma_set_file(vma, anon);
+ /* Drop the initial creation reference, the vma is now holding one. */
+ fput(anon);
switch (mmo->mmap_type) {
case I915_MMAP_TYPE_WC:
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index de915ff6f4b4..a71f42870d5e 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -223,10 +223,8 @@ int msm_gem_mmap_obj(struct drm_gem_object *obj,
* address_space (so unmap_mapping_range does what we want,
* in particular in the case of mmap'd dmabufs)
*/
- fput(vma->vm_file);
- get_file(obj->filp);
vma->vm_pgoff = 0;
- vma->vm_file = obj->filp;
+ vma_set_file(vma, obj->filp);
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
}
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 979d53a93c2b..0d4542ff1d7d 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c
@@ -564,9 +564,8 @@ int omap_gem_mmap_obj(struct drm_gem_object *obj,
* address_space (so unmap_mapping_range does what we want,
* in particular in the case of mmap'd dmabufs)
*/
- fput(vma->vm_file);
vma->vm_pgoff = 0;
- vma->vm_file = get_file(obj->filp);
+ vma_set_file(vma, obj->filp);
vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
}
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index fa54a6d1403d..ea0eecae5153 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -397,8 +397,7 @@ static int vgem_prime_mmap(struct drm_gem_object *obj,
if (ret)
return ret;
- fput(vma->vm_file);
- vma->vm_file = get_file(obj->filp);
+ vma_set_file(vma, obj->filp);
vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/ashmem.c
index 10b4be1f3e78..4789d36ddfd3 100644
--- a/drivers/staging/android/ashmem.c
+++ b/drivers/staging/android/ashmem.c
@@ -450,9 +450,9 @@ static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
vma_set_anonymous(vma);
}
- if (vma->vm_file)
- fput(vma->vm_file);
- vma->vm_file = asma->file;
+ vma_set_file(vma, asma->file);
+ /* XXX: merge this with the get_file() above if possible */
+ fput(asma->file);
out:
mutex_unlock(&ashmem_mutex);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ca6e6a81576b..f7a005153d02 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2693,6 +2693,8 @@ static inline void vma_set_page_prot(struct vm_area_struct *vma)
}
#endif
+void vma_set_file(struct vm_area_struct *vma, struct file *file);
+
#ifdef CONFIG_NUMA_BALANCING
unsigned long change_prot_numa(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
diff --git a/mm/mmap.c b/mm/mmap.c
index 3a2670d73355..8634d0bb54ad 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -136,6 +136,18 @@ void vma_set_page_prot(struct vm_area_struct *vma)
WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
}
+/*
+ * Change backing file, only valid to use during initial VMA setup.
+ */
+void vma_set_file(struct vm_area_struct *vma, struct file *file)
+{
+ /* Changing an anonymous vma with this is illegal */
+ get_file(file);
+ swap(vma->vm_file, file);
+ fput(file);
+}
+EXPORT_SYMBOL(vma_set_file);
+
/*
* Requires inode->i_mapping->i_mmap_rwsem
*/
--
2.17.1
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