Re: [Qemu-devel] [PATCH] io: Fix double shift usages on QIOChannel features

["Marc-André Lureau" <mlureau@redhat.com>]

Hi

----- Original Message -----
> Hi Marc,
> 
> > On 27 Sep 2016, at 18:12, Marc-André Lureau <mlureau@redhat.com> wrote:
> > 
> > Hi
> > 
> > ----- Original Message -----
> >> When QIOChannels were introduced in 666a3af9, the feature bits were
> >> defined shifted. However, when using them, the code was shifting them
> >> again. The incorrect use was consistent until 74b6ce43, where
> >> QIO_CHANNEL_FEATURE_LISTEN was defined shifted but tested unshifted.
> >> 
> > 
> > And by luck, QIO_CHANNEL_FEATURE_LISTEN == (1 <<
> > QIO_CHANNEL_FEATURE_LISTEN), so it works :)

Oops, they are not, QIO_CHANNEL_FEATURE_LISTEN == 4 (I read 2), then I wonder how could 74b6ce43e work..

> 
> Can you elaborate on that? Maybe I'm missing something obvious, but I'm
> confused as to how they are equivalent.
> 
> Thanks,
> Felipe
> 
> > 
> >> This patch fixes all uses of QIOChannel features. They are defined
> >> shifted and therefore set unshifted. It also makes all feature tests to
> >> use the qio_channel_has_feature() function.
> > 
> > Looks good, we may want to have it in -stable.
> > 
> >> 
> >> Signed-off-by: Felipe Franciosi <felipe@nutanix.com>
> > 
> > Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> > 
> >> ---
> >> io/channel-socket.c           |   11 ++++++-----
> >> io/channel-tls.c              |    4 ++--
> >> io/channel-websock.c          |    4 ++--
> >> io/channel.c                  |   10 ++++------
> >> migration/qemu-file-channel.c |    3 +--
> >> qemu-char.c                   |    3 +--
> >> 6 files changed, 16 insertions(+), 19 deletions(-)
> >> 
> >> diff --git a/io/channel-socket.c b/io/channel-socket.c
> >> index 196a4f1..bb0a0a7 100644
> >> --- a/io/channel-socket.c
> >> +++ b/io/channel-socket.c
> >> @@ -55,7 +55,7 @@ qio_channel_socket_new(void)
> >>     sioc->fd = -1;
> >> 
> >>     ioc = QIO_CHANNEL(sioc);
> >> -    ioc->features |= (1 << QIO_CHANNEL_FEATURE_SHUTDOWN);
> >> +    ioc->features |= QIO_CHANNEL_FEATURE_SHUTDOWN;
> >> 
> >> #ifdef WIN32
> >>     ioc->event = CreateEvent(NULL, FALSE, FALSE, NULL);
> >> @@ -107,12 +107,12 @@ qio_channel_socket_set_fd(QIOChannelSocket *sioc,
> >> #ifndef WIN32
> >>     if (sioc->localAddr.ss_family == AF_UNIX) {
> >>         QIOChannel *ioc = QIO_CHANNEL(sioc);
> >> -        ioc->features |= (1 << QIO_CHANNEL_FEATURE_FD_PASS);
> >> +        ioc->features |= QIO_CHANNEL_FEATURE_FD_PASS;
> >>     }
> >> #endif /* WIN32 */
> >>     if (getsockopt(fd, SOL_SOCKET, SO_ACCEPTCONN, &val, &len) == 0 && val)
> >>     {
> >>         QIOChannel *ioc = QIO_CHANNEL(sioc);
> >> -        ioc->features |= (1 << QIO_CHANNEL_FEATURE_LISTEN);
> >> +        ioc->features |= QIO_CHANNEL_FEATURE_LISTEN;
> >>     }
> >> 
> >>     return 0;
> >> @@ -380,7 +380,7 @@ qio_channel_socket_accept(QIOChannelSocket *ioc,
> >> 
> >> #ifndef WIN32
> >>     if (cioc->localAddr.ss_family == AF_UNIX) {
> >> -        QIO_CHANNEL(cioc)->features |= (1 <<
> >> QIO_CHANNEL_FEATURE_FD_PASS);
> >> +        QIO_CHANNEL(cioc)->features |= QIO_CHANNEL_FEATURE_FD_PASS;
> >>     }
> >> #endif /* WIN32 */
> >> 
> >> @@ -403,7 +403,8 @@ static void qio_channel_socket_finalize(Object *obj)
> >>     QIOChannelSocket *ioc = QIO_CHANNEL_SOCKET(obj);
> >> 
> >>     if (ioc->fd != -1) {
> >> -        if (QIO_CHANNEL(ioc)->features & QIO_CHANNEL_FEATURE_LISTEN) {
> >> +        if (qio_channel_has_feature(QIO_CHANNEL(ioc),
> >> +                                    QIO_CHANNEL_FEATURE_LISTEN)) {
> >>             Error *err = NULL;
> >> 
> >>             socket_listen_cleanup(ioc->fd, &err);
> >> diff --git a/io/channel-tls.c b/io/channel-tls.c
> >> index 9a8525c..d22996b 100644
> >> --- a/io/channel-tls.c
> >> +++ b/io/channel-tls.c
> >> @@ -111,8 +111,8 @@ qio_channel_tls_new_client(QIOChannel *master,
> >>     ioc = QIO_CHANNEL(tioc);
> >> 
> >>     tioc->master = master;
> >> -    if (master->features & (1 << QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> >> -        ioc->features |= (1 << QIO_CHANNEL_FEATURE_SHUTDOWN);
> >> +    if (qio_channel_has_feature(master, QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> >> +        ioc->features |= QIO_CHANNEL_FEATURE_SHUTDOWN;
> >>     }
> >>     object_ref(OBJECT(master));
> >> 
> >> diff --git a/io/channel-websock.c b/io/channel-websock.c
> >> index 533bd4b..9accd16 100644
> >> --- a/io/channel-websock.c
> >> +++ b/io/channel-websock.c
> >> @@ -497,8 +497,8 @@ qio_channel_websock_new_server(QIOChannel *master)
> >>     ioc = QIO_CHANNEL(wioc);
> >> 
> >>     wioc->master = master;
> >> -    if (master->features & (1 << QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> >> -        ioc->features |= (1 << QIO_CHANNEL_FEATURE_SHUTDOWN);
> >> +    if (qio_channel_has_feature(master, QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> >> +        ioc->features |= QIO_CHANNEL_FEATURE_SHUTDOWN;
> >>     }
> >>     object_ref(OBJECT(master));
> >> 
> >> diff --git a/io/channel.c b/io/channel.c
> >> index 923c465..ebe9f86 100644
> >> --- a/io/channel.c
> >> +++ b/io/channel.c
> >> @@ -23,13 +23,11 @@
> >> #include "qapi/error.h"
> >> #include "qemu/coroutine.h"
> >> 
> >> -bool qio_channel_has_feature(QIOChannel *ioc,
> >> -                             QIOChannelFeature feature)
> >> +bool qio_channel_has_feature(QIOChannel *ioc, QIOChannelFeature feature)
> >> {
> >> -    return ioc->features & (1 << feature);
> >> +    return ioc->features & feature;
> >> }
> >> 
> >> -
> >> ssize_t qio_channel_readv_full(QIOChannel *ioc,
> >>                                const struct iovec *iov,
> >>                                size_t niov,
> >> @@ -40,7 +38,7 @@ ssize_t qio_channel_readv_full(QIOChannel *ioc,
> >>     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
> >> 
> >>     if ((fds || nfds) &&
> >> -        !(ioc->features & (1 << QIO_CHANNEL_FEATURE_FD_PASS))) {
> >> +        !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
> >>         error_setg_errno(errp, EINVAL,
> >>                          "Channel does not support file descriptor
> >>                          passing");
> >>         return -1;
> >> @@ -60,7 +58,7 @@ ssize_t qio_channel_writev_full(QIOChannel *ioc,
> >>     QIOChannelClass *klass = QIO_CHANNEL_GET_CLASS(ioc);
> >> 
> >>     if ((fds || nfds) &&
> >> -        !(ioc->features & (1 << QIO_CHANNEL_FEATURE_FD_PASS))) {
> >> +        !qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
> >>         error_setg_errno(errp, EINVAL,
> >>                          "Channel does not support file descriptor
> >>                          passing");
> >>         return -1;
> >> diff --git a/migration/qemu-file-channel.c b/migration/qemu-file-channel.c
> >> index 45c13f1..a39abd5 100644
> >> --- a/migration/qemu-file-channel.c
> >> +++ b/migration/qemu-file-channel.c
> >> @@ -105,8 +105,7 @@ static int channel_shutdown(void *opaque,
> >> {
> >>     QIOChannel *ioc = QIO_CHANNEL(opaque);
> >> 
> >> -    if (qio_channel_has_feature(ioc,
> >> -                                QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> >> +    if (qio_channel_has_feature(ioc, QIO_CHANNEL_FEATURE_SHUTDOWN)) {
> >>         QIOChannelShutdown mode;
> >>         if (rd && wr) {
> >>             mode = QIO_CHANNEL_SHUTDOWN_BOTH;
> >> diff --git a/qemu-char.c b/qemu-char.c
> >> index 8826419..b825331 100644
> >> --- a/qemu-char.c
> >> +++ b/qemu-char.c
> >> @@ -2787,8 +2787,7 @@ static int tcp_set_msgfds(CharDriverState *chr, int
> >> *fds, int num)
> >>     s->write_msgfds_num = 0;
> >> 
> >>     if (!s->connected ||
> >> -        !qio_channel_has_feature(s->ioc,
> >> -                                 QIO_CHANNEL_FEATURE_FD_PASS)) {
> >> +        !qio_channel_has_feature(s->ioc, QIO_CHANNEL_FEATURE_FD_PASS)) {
> >>         return -1;
> >>     }
> >> 
> >> --
> >> 1.7.1
> >> 
> >> 
> 
>