From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zheng Li Subject: Re: [PATCH for-4.5] tools/oxenstored: Fix | vs & error in fd event handling Date: Wed, 26 Nov 2014 15:38:07 +0000 Message-ID: <5475F3DF.2070907@zheng.li> References: <1417014580-27611-1-git-send-email-andrew.cooper3@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1417014580-27611-1-git-send-email-andrew.cooper3@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrew Cooper , Xen-devel Cc: Wei Liu , Ian Campbell , Ian Jackson , Zheng Li , Dave Scott List-Id: xen-devel@lists.xenproject.org On 26/11/2014 15:09, Andrew Cooper wrote: > This makes fields 0 and 1 true more often than they should be, resulting > problems when handling events. Indeed, looks like a mistake I made when rewriting the logic terms lately. The result is POLLUP or POLLERR events being returned in more categories than we'd interest. Thanks for fixing this! Acked-by: Zheng Li Cheers, Zheng > --- > > This was discovered with XenServers internal Coverity instance. I have yet to > work out why the issue is not identified by the upstream coverity scanning. > > Konrad: This is a bug in the default event handling used by oxenstored in 4.5, > as the default switched from select() to poll() in the 4.5 timeframe. It > would appear that the negative side effects are limited to just logspam about > certain clients attempting invalid actions, but I can't rule out anything more > problematic. > --- > tools/ocaml/xenstored/select_stubs.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/ocaml/xenstored/select_stubs.c b/tools/ocaml/xenstored/select_stubs.c > index 4a8edb5..af72b84 100644 > --- a/tools/ocaml/xenstored/select_stubs.c > +++ b/tools/ocaml/xenstored/select_stubs.c > @@ -56,8 +56,8 @@ CAMLprim value stub_select_on_poll(value fd_events, value timeo) { > events = Field(Field(fd_events, i), 1); > > if (c_fds[i].revents & POLLNVAL) unix_error(EBADF, "select", Nothing); > - Field(events, 0) = Val_bool(c_fds[i].events | POLLIN && c_fds[i].revents & (POLLIN |POLLHUP|POLLERR)); > - Field(events, 1) = Val_bool(c_fds[i].events | POLLOUT && c_fds[i].revents & (POLLOUT|POLLHUP|POLLERR)); > + Field(events, 0) = Val_bool(c_fds[i].events & POLLIN && c_fds[i].revents & (POLLIN |POLLHUP|POLLERR)); > + Field(events, 1) = Val_bool(c_fds[i].events & POLLOUT && c_fds[i].revents & (POLLOUT|POLLHUP|POLLERR)); > Field(events, 2) = Val_bool(c_fds[i].revents & POLLPRI); > > } >