Messages in this thread |  | | Date | Tue, 25 Feb 2014 10:21:44 +0000 | From | Eric Wong <> | Subject | Re: [RFC PATCH for-next 4/4] epoll: epoll() syscall definition |
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Nathaniel Yazdani <n1ght.4nd.d4y@gmail.com> wrote: > + * stores triggered eventpoll entries in the 'out' array. The input array is > + * _not_ read-only, because the resulting event mask gets written back to each > + * entry's ->ep_events field. When successful, this will be the same as before > + * (plus EPOLLERR & EPOLLHUP). If ->ep_events gets cleared, then it is reasonable > + * to infer that the entry's ->ep_fildes was a bad file descriptor. > + */
> + if (!access_ok(VERIFY_WRITE, in, inc * sizeof(struct epoll))) > + goto out; > + for (i = 0; i < inc; ++i) { > + int fd, io; > + long long id; > + > + ret = -EFAULT; > + if (__get_user(fd, &in[i].ep_fildes) || > + __get_user(io, &in[i].ep_events) || > + __get_user(id, &in[i].ep_ident)) > + goto out; > + > + ep_control(file->private_data, fd, &io, id, 0); > + ret = -EFAULT; > + if (__put_user(io, &in[i].ep_events)) > + goto out;
I don't think we should waste cycles writing to 'in' on success.
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