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Subject[PATCH] drivers/gpu/drm/i915/i915_gem.c: Add missing error handling code
Date
From: Julia Lawall <julia@diku.dk>

The cleanup code at the end of the function should also be carried out when
the function only partly completes its work.

A simplified version of the semantic match that finds this problem is:
(http://coccinelle.lip6.fr/)

// <smpl>
@r exists@
local idexpression struct page ** x;
expression ra,rr;
position p1,p2;
@@

x = drm_malloc_ab@p1(...)
... when != x = rr
when != drm_free_large(x,...)
when != if (...) { ... drm_free_large(x,...) ...}
if(...) { ... when != x = ra
when forall
when != drm_free_large(x,...)
\(return <+...x...+>; \| return@p2...; \) }

@script:python@
p1 << r.p1;
p2 << r.p2;
@@

cocci.print_main("drm_malloc_ab",p1)
cocci.print_secs("return",p2)

// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
This is only compile-tested. It may be that processing all of the pages is
not correct when they have been partially treated.

drivers/gpu/drm/i915/i915_gem.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7ce3f35..ef000e6 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -467,8 +467,10 @@ i915_gem_shmem_pread_slow(struct drm_device *dev,

page = read_cache_page_gfp(mapping, offset >> PAGE_SHIFT,
GFP_HIGHUSER | __GFP_RECLAIMABLE);
- if (IS_ERR(page))
- return PTR_ERR(page);
+ if (IS_ERR(page)) {
+ ret = PTR_ERR(page);
+ goto out;
+ }

if (do_bit17_swizzling) {
slow_shmem_bit17_copy(page,


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