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drm/i915: Fix lock order reversal in shmem pwrite path.

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Like the GTT pwrite path fix, this uses an optimistic path and a
fallback to get_user_pages.  Note that this means we have to stop using
vfs_write and roll it ourselves.

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Eric Anholt 2009-03-09 13:42:30 -07:00
parent 856fa1988e
commit 40123c1f8d
1 changed files with 206 additions and 21 deletions
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227
drivers/gpu/drm/i915/i915_gem.c
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@ -136,6 +136,33 @@ i915_gem_create_ioctl(struct drm_device *dev, void *data,
return 0;
}
static inline int
slow_shmem_copy(struct page *dst_page,
int dst_offset,
struct page *src_page,
int src_offset,
int length)
{
char *dst_vaddr, *src_vaddr;
dst_vaddr = kmap_atomic(dst_page, KM_USER0);
if (dst_vaddr == NULL)
return -ENOMEM;
src_vaddr = kmap_atomic(src_page, KM_USER1);
if (src_vaddr == NULL) {
kunmap_atomic(dst_vaddr, KM_USER0);
return -ENOMEM;
}
memcpy(dst_vaddr + dst_offset, src_vaddr + src_offset, length);
kunmap_atomic(src_vaddr, KM_USER1);
kunmap_atomic(dst_vaddr, KM_USER0);
return 0;
}
/**
* Reads data from the object referenced by handle.
*
@ -243,6 +270,23 @@ slow_kernel_write(struct io_mapping *mapping,
return 0;
}
static inline int
fast_shmem_write(struct page **pages,
loff_t page_base, int page_offset,
char __user *data,
int length)
{
char __iomem *vaddr;
vaddr = kmap_atomic(pages[page_base >> PAGE_SHIFT], KM_USER0);
if (vaddr == NULL)
return -ENOMEM;
__copy_from_user_inatomic(vaddr + page_offset, data, length);
kunmap_atomic(vaddr, KM_USER0);
return 0;
}
/**
* This is the fast pwrite path, where we copy the data directly from the
* user into the GTT, uncached.
@ -423,39 +467,175 @@ out_unpin_pages:
return ret;
}
/**
* This is the fast shmem pwrite path, which attempts to directly
* copy_from_user into the kmapped pages backing the object.
*/
static int
i915_gem_shmem_pwrite(struct drm_device *dev, struct drm_gem_object *obj,
struct drm_i915_gem_pwrite *args,
struct drm_file *file_priv)
i915_gem_shmem_pwrite_fast(struct drm_device *dev, struct drm_gem_object *obj,
struct drm_i915_gem_pwrite *args,
struct drm_file *file_priv)
{
struct drm_i915_gem_object *obj_priv = obj->driver_private;
ssize_t remain;
loff_t offset, page_base;
char __user *user_data;
int page_offset, page_length;
int ret;
loff_t offset;
ssize_t written;
user_data = (char __user *) (uintptr_t) args->data_ptr;
remain = args->size;
mutex_lock(&dev->struct_mutex);
ret = i915_gem_object_get_pages(obj);
if (ret != 0)
goto fail_unlock;
ret = i915_gem_object_set_to_cpu_domain(obj, 1);
if (ret) {
mutex_unlock(&dev->struct_mutex);
return ret;
}
if (ret != 0)
goto fail_put_pages;
obj_priv = obj->driver_private;
offset = args->offset;
obj_priv->dirty = 1;
written = vfs_write(obj->filp,
(char __user *)(uintptr_t) args->data_ptr,
args->size, &offset);
if (written != args->size) {
mutex_unlock(&dev->struct_mutex);
if (written < 0)
return written;
else
return -EINVAL;
while (remain > 0) {
/* Operation in this page
*
* page_base = page offset within aperture
* page_offset = offset within page
* page_length = bytes to copy for this page
*/
page_base = (offset & ~(PAGE_SIZE-1));
page_offset = offset & (PAGE_SIZE-1);
page_length = remain;
if ((page_offset + remain) > PAGE_SIZE)
page_length = PAGE_SIZE - page_offset;
ret = fast_shmem_write(obj_priv->pages,
page_base, page_offset,
user_data, page_length);
if (ret)
goto fail_put_pages;
remain -= page_length;
user_data += page_length;
offset += page_length;
}
fail_put_pages:
i915_gem_object_put_pages(obj);
fail_unlock:
mutex_unlock(&dev->struct_mutex);
return 0;
return ret;
}
/**
* This is the fallback shmem pwrite path, which uses get_user_pages to pin
* the memory and maps it using kmap_atomic for copying.
*
* This avoids taking mmap_sem for faulting on the user's address while the
* struct_mutex is held.
*/
static int
i915_gem_shmem_pwrite_slow(struct drm_device *dev, struct drm_gem_object *obj,
struct drm_i915_gem_pwrite *args,
struct drm_file *file_priv)
{
struct drm_i915_gem_object *obj_priv = obj->driver_private;
struct mm_struct *mm = current->mm;
struct page **user_pages;
ssize_t remain;
loff_t offset, pinned_pages, i;
loff_t first_data_page, last_data_page, num_pages;
int shmem_page_index, shmem_page_offset;
int data_page_index, data_page_offset;
int page_length;
int ret;
uint64_t data_ptr = args->data_ptr;
remain = args->size;
/* Pin the user pages containing the data. We can't fault while
* holding the struct mutex, and all of the pwrite implementations
* want to hold it while dereferencing the user data.
*/
first_data_page = data_ptr / PAGE_SIZE;
last_data_page = (data_ptr + args->size - 1) / PAGE_SIZE;
num_pages = last_data_page - first_data_page + 1;
user_pages = kcalloc(num_pages, sizeof(struct page *), GFP_KERNEL);
if (user_pages == NULL)
return -ENOMEM;
down_read(&mm->mmap_sem);
pinned_pages = get_user_pages(current, mm, (uintptr_t)args->data_ptr,
num_pages, 0, 0, user_pages, NULL);
up_read(&mm->mmap_sem);
if (pinned_pages < num_pages) {
ret = -EFAULT;
goto fail_put_user_pages;
}
mutex_lock(&dev->struct_mutex);
ret = i915_gem_object_get_pages(obj);
if (ret != 0)
goto fail_unlock;
ret = i915_gem_object_set_to_cpu_domain(obj, 1);
if (ret != 0)
goto fail_put_pages;
obj_priv = obj->driver_private;
offset = args->offset;
obj_priv->dirty = 1;
while (remain > 0) {
/* Operation in this page
*
* shmem_page_index = page number within shmem file
* shmem_page_offset = offset within page in shmem file
* data_page_index = page number in get_user_pages return
* data_page_offset = offset with data_page_index page.
* page_length = bytes to copy for this page
*/
shmem_page_index = offset / PAGE_SIZE;
shmem_page_offset = offset & ~PAGE_MASK;
data_page_index = data_ptr / PAGE_SIZE - first_data_page;
data_page_offset = data_ptr & ~PAGE_MASK;
page_length = remain;
if ((shmem_page_offset + page_length) > PAGE_SIZE)
page_length = PAGE_SIZE - shmem_page_offset;
if ((data_page_offset + page_length) > PAGE_SIZE)
page_length = PAGE_SIZE - data_page_offset;
ret = slow_shmem_copy(obj_priv->pages[shmem_page_index],
shmem_page_offset,
user_pages[data_page_index],
data_page_offset,
page_length);
if (ret)
goto fail_put_pages;
remain -= page_length;
data_ptr += page_length;
offset += page_length;
}
fail_put_pages:
i915_gem_object_put_pages(obj);
fail_unlock:
mutex_unlock(&dev->struct_mutex);
fail_put_user_pages:
for (i = 0; i < pinned_pages; i++)
page_cache_release(user_pages[i]);
kfree(user_pages);
return ret;
}
/**
@ -502,8 +682,13 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
ret = i915_gem_gtt_pwrite_slow(dev, obj, args,
file_priv);
}
} else
ret = i915_gem_shmem_pwrite(dev, obj, args, file_priv);
} else {
ret = i915_gem_shmem_pwrite_fast(dev, obj, args, file_priv);
if (ret == -EFAULT) {
ret = i915_gem_shmem_pwrite_slow(dev, obj, args,
file_priv);
}
}
#if WATCH_PWRITE
if (ret)