On 04/10, Peter Zijlstra wrote: > > On Wed, Apr 09, 2014 at 09:49:57PM +0200, Peter Zijlstra wrote: > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -2377,6 +2377,9 @@ extern bool current_is_single_threaded(void); > /* > * Careful: do_each_thread/while_each_thread is a double loop so > * 'break' will not work as expected - use goto instead. > + * > + * Deprecated; use for_each_thread() instead; this has serious issues with > + * g != current and RCU. > */
Yes, thanks. > #define do_each_thread(g, t) \ > for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do > @@ -2384,11 +2387,8 @@ extern bool current_is_single_threaded(void); > #define while_each_thread(g, t) \ > while ((t = next_thread(t)) != g) > > -#define __for_each_thread(signal, t) \ > - list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node) > - > #define for_each_thread(p, t) \ > - __for_each_thread((p)->signal, t) > + list_for_each_entry_rcu(t, &(p)->signal->thread_head, thread_node) Why? __for_each_thread(signal) can generate a better code, if we do care. In fact, ignoring the bad "signal" name, __for_each_thread(signal, t) even looks better. "signal" represents the whole thread group. But I won't argue. Besides, this reminds me about CONST_CAST() and making task_struct->signal "const". This can improve the code generation too. > +static inline __deprecated > +struct task_struct *next_thread(const struct task_struct *p) > { Not sure... But probably fine too. I already killed some users of next_thread(). This reminds me about next_tid(), probably it should be converted too. As for, say, __exit_signal() it really needs next_thread(). We can fix it instead of deprecating, or we can add another one with another name. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/