Messages in this thread Patch in this message | | | Date | Mon, 15 Dec 2008 18:09:37 +0100 | From | Oleg Nesterov <> | Subject | Re: broken do_each_pid_{thread,task} |
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On 12/15, Oleg Nesterov wrote: > > On 12/14, Eric W. Biederman wrote: > > > > Although seeing the unexpected corner case it gets us into I think it would > > be good to reconsider this test.
So. I can't decide whether this patch is cleanup or the further uglification, but if anyone likes it I will be happy to send it.
Then we can kill do_each_pid_task/while_each_pid_task completely.
Oleg.
--- linux-2.6.27/include/linux/pid.h~PID_FOR_EACH 2008-10-10 00:13:53.000000000 +0200 +++ linux-2.6.27/include/linux/pid.h 2008-12-15 17:51:50.000000000 +0100 @@ -144,21 +144,25 @@ static inline pid_t pid_nr(struct pid *p pid_t pid_nr_ns(struct pid *pid, struct pid_namespace *ns); pid_t pid_vnr(struct pid *pid); +/* + * Both old and new leaders may be attached to the same pid in the + * middle of de_thread(), that is why we do the special check for + * PIDTYPE_PID below. + */ +#define pid_for_each_task(pid, type, p) \ + for (p = (pid) ? (void*)(pid)->tasks[type].first : NULL; \ + rcu_dereference(p) && ({ \ + prefetch(((struct hlist_node*)p)->next); \ + p = hlist_entry((void*)p, typeof(*p), pids[type].node); \ + 1; }); \ + p = ((type) != PIDTYPE_PID) ? \ + (void*)(p)->pids[type].node.next : NULL) + #define do_each_pid_task(pid, type, task) \ do { \ - struct hlist_node *pos___; \ - if (pid != NULL) \ - hlist_for_each_entry_rcu((task), pos___, \ - &pid->tasks[type], pids[type].node) { + pid_for_each_task(pid, type, task) - /* - * Both old and new leaders may be attached to - * the same pid in the middle of de_thread(). - */ #define while_each_pid_task(pid, type, task) \ - if (type == PIDTYPE_PID) \ - break; \ - } \ } while (0) #define do_each_pid_thread(pid, type, task) \
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