On Sat, Mar 24, 2012 at 01:52:54PM +0100, Peter Zijlstra wrote: [...] > > p.s. I know Peter Zijlstra detest the __cond_lock() stuff, but untill > > we have anything better in sparse, let's use it. This particular > > patch helped me to detect one bug that I myself made during > > task->mm fixup series. So, it is useful. > > Yeah, so Nacked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> > > Also, why didn't lockdep catch it? Because patch authors test their patches on architectures they own (well, sometimes I do check patches on exotic architectures w/ qemu, but it is less convenient than just build/sparse-test the patch w/ a cross compiler). And since lockdep is a runtime checker, it is not very useful. Sparse is a build-time checker, so it is even better in the sense that it is able to catch bugs even in code that is executed rarely. > Fix sparse already instead of smearing ugly all over. Just wonder how do you see the feature implemented? Something like this? #define __ret_cond_locked(l, c) __attribute__((ret_cond_locked(l, c))) #define __ret_value __attribute__((ret_value)) #define __ret_locked_nonnull(l) __ret_cond_locked(l, __ret_value); extern struct task_struct *find_lock_task_mm(struct task_struct *p) __ret_locked_nonnull(&__ret_value->alloc_lock); Thanks, -- Anton Vorontsov Email: cbouatmailru@xxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>