Hi all,
I'm recently collecting collateral evolutions in Linux, inferring the
patterns in these patches and generate semantic patches for maintainers
of out-of-tree modules. During the work I am not sure how to express the
following cases in SmPL.
1. add a reader for a structure field
For example, in the following code
1 int foo(struct device* dev, int mask) {
2 int old_flags = dev->flags;
3 dev->flags &= mask;
4 return (dev->flags == old_flags);
5 }
'dev->flags' need to be replaced by 'dev_flags(dev)' where
dev_flags(dev) is a function returning 'dev->flags'. The following
semantic patch:
@@
struct device *dev;
@@
-dev->flags
+dev_flags(dev)
will rewrites all occurences of 'dev->flags', including the one on
line 3, which makes the program incorrect. How can I avoid touching
line 3 while updating line 2 and line 4 using spatch?
Related commits:
-
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=2f064f3485cd29633ad1b3cfb00cc519509a3d72
-
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4d0e965732db6f7cce78e6b8f5d3073249004c3a
2. rewriting part of a branch condition
int foo(int i, int j) {
if (i > 3 && i < 10 && j > 5 && j < 8)
return i;
return j;
}
If a commit replaces (i < 10 && j > 5) with (i < 8) (the order of
comparisons and logical operators are fixed), how can I express this
pattern in SmPL?
I have tried the following, but it does not work.
@@
identifier foo, i, j;
@@
foo(int i, int j) {
<...
- i < 10 && j > 5
+ i < 8
...>
}
Related commit:
-
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=dc3f4198eac14e52a98dfc79cd84b45e280f59cd
3. add a statement right after local variable declarations
In the following function,
int foo(int i) {
int j,k,l;
j = baz(i);
...
}
How can I add the statement 'bar(i);' before 'j = baz(i)' but after
the local variable declarations?
Related commit:
-
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=54efd50bfd873e2dbf784e0b21a8027ba4299a3e
4. change callback prototypes
Assume a driver defines a global structure initialized with
callbacks:
1 int foo(int i, int j) { ... }
2 int bar(int i, int j) { ... }
3
4 struct netdev_ops ops = {
5 .foo = foo,
6 };
and a commit requires the prototype of the callback being changed to
foo(int i, int j, intk), how can I achieve that without touching
bar() using spatch?
Related commit:
-
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=88e72717c2de4181d8a6de1b04315953ad2bebdf
-
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=dece16353ef47d8d33f5302bc158072a9d65e26f
--
Best Regards
Junjie Mao
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