On 12/14/2011 08:08 PM, Josh Triplett wrote:
> In the Linux kernel, "current" refers to the current task, of type
> "struct task_struct *", by way of a stack of (sometimes arch-specific)
> macros. For instance, arch/x86/include/asm/current.h defines current as
> get_current(), an inline function returning "struct task_struct *".
> Other architectures, as well as asm-generic, use variations on the same
> theme with varying depths of macros.
>
> However, coccinelle doesn't seem to manage to figure out the type of
> current, because rules defined with @@struct task_struct *task;@@ don't
> match current.
>
> I can work around this by writing a duplicate set of rules with
> @@identifier current;@@, but I'd rather not have to introduce that
> duplication.
>
> For a test case, try the following semantic patch:
>
> @@ struct task_struct *task; @@
> - (task)->pid == 0
> + is_idle_task(task)
>
> @@ struct task_struct *task; @@
> - (task)->pid != 0
> + !is_idle_task(task)
>
>
> And the following test file:
>
> #include <linux/sched.h>
> extern struct task_struct *t;
> void context(void)
> {
> if (t->pid)
> do_something();
> if (current->pid)
> do_something();
> }
>
>
> Coccinelle successfully patches the first condition, but not the second.
Did you ran spatch with -all_includes?
Your example works fine here when I pass -all_includes:
@@ -4,9 +4,9 @@
extern struct task_struct *t;
void context(void)
{
- if (t->pid)
+ if (!is_idle_task(t))
do_something();
- if (current->pid)
+ if (!is_idle_task(current))
do_something();
}
- Lars
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