diff options
| author | Jerome Glisse <jglisse@redhat.com> | 2009-11-13 20:56:58 +0100 |
|---|---|---|
| committer | Dave Airlie <airlied@redhat.com> | 2009-11-24 13:02:18 +1000 |
| commit | a698cf34ea867efef12fc29dd63d443f0c71a53c (patch) | |
| tree | a396804737c4a7bc972f04fe97d0ec0a2f971668 /drivers/gpu/drm | |
| parent | 0beb81ab45c67de4b3aa85faad604cff8ed133a8 (diff) | |
| download | linux-next-a698cf34ea867efef12fc29dd63d443f0c71a53c.tar.gz | |
drm: mm always protect change to unused_nodes with unused_lock spinlock
unused_nodes modification needs to be protected by unused_lock spinlock.
Here is an example of an usage where there is no such protection without
this patch.
Process 1: 1-drm_mm_pre_get(this function modify unused_nodes list)
2-spin_lock(spinlock protecting mm struct)
3-drm_mm_put_block(this function might modify unused_nodes
list but doesn't protect modification with unused_lock)
4-spin_unlock(spinlock protecting mm struct)
Process2: 1-drm_mm_pre_get(this function modify unused_nodes list)
At this point Process1 & Process2 might both be doing modification to
unused_nodes list. This patch add unused_lock protection into
drm_mm_put_block to avoid such issue.
Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Diffstat (limited to 'drivers/gpu/drm')
| -rw-r--r-- | drivers/gpu/drm/drm_mm.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index c861d80fd779..97dc5a4f0de4 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -103,6 +103,11 @@ static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic) return child; } +/* drm_mm_pre_get() - pre allocate drm_mm_node structure + * drm_mm: memory manager struct we are pre-allocating for + * + * Returns 0 on success or -ENOMEM if allocation fails. + */ int drm_mm_pre_get(struct drm_mm *mm) { struct drm_mm_node *node; @@ -253,12 +258,14 @@ void drm_mm_put_block(struct drm_mm_node *cur) prev_node->size += next_node->size; list_del(&next_node->ml_entry); list_del(&next_node->fl_entry); + spin_lock(&mm->unused_lock); if (mm->num_unused < MM_UNUSED_TARGET) { list_add(&next_node->fl_entry, &mm->unused_nodes); ++mm->num_unused; } else kfree(next_node); + spin_unlock(&mm->unused_lock); } else { next_node->size += cur->size; next_node->start = cur->start; @@ -271,11 +278,13 @@ void drm_mm_put_block(struct drm_mm_node *cur) list_add(&cur->fl_entry, &mm->fl_entry); } else { list_del(&cur->ml_entry); + spin_lock(&mm->unused_lock); if (mm->num_unused < MM_UNUSED_TARGET) { list_add(&cur->fl_entry, &mm->unused_nodes); ++mm->num_unused; } else kfree(cur); + spin_unlock(&mm->unused_lock); } } |