From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wen Congyang Subject: Re: [PATCH 22/29] tools/libxl: Allow limiting amount copied by datacopier Date: Fri, 12 Sep 2014 16:36:37 +0800 Message-ID: <5412B095.4020805@cn.fujitsu.com> References: <1410369067-1330-1-git-send-email-andrew.cooper3@citrix.com> <1410369067-1330-23-git-send-email-andrew.cooper3@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1410369067-1330-23-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: Ross Lagerwall , Ian Jackson , Ian Campbell List-Id: xen-devel@lists.xenproject.org On 09/11/2014 01:11 AM, Andrew Cooper wrote: > From: Ross Lagerwall > > Add a parameter, maxread, to limit the amount of data read from the > source fd of a datacopier. > > Signed-off-by: Ross Lagerwall > --- > tools/libxl/libxl_aoutils.c | 9 +++++++-- > tools/libxl/libxl_bootloader.c | 2 ++ > tools/libxl/libxl_dom.c | 1 + > tools/libxl/libxl_internal.h | 1 + > 4 files changed, 11 insertions(+), 2 deletions(-) > > diff --git a/tools/libxl/libxl_aoutils.c b/tools/libxl/libxl_aoutils.c > index caba637..6502325 100644 > --- a/tools/libxl/libxl_aoutils.c > +++ b/tools/libxl/libxl_aoutils.c > @@ -145,7 +145,7 @@ static void datacopier_check_state(libxl__egc *egc, libxl__datacopier_state *dc) > return; > } > } > - } else if (!libxl__ev_fd_isregistered(&dc->toread)) { > + } else if (!libxl__ev_fd_isregistered(&dc->toread) || dc->maxread == 0) { > /* we have had eof */ > datacopier_callback(egc, dc, 0, 0); > return; > @@ -233,7 +233,8 @@ static void datacopier_readable(libxl__egc *egc, libxl__ev_fd *ev, > } > int r = read(ev->fd, > buf->buf + buf->used, > - sizeof(buf->buf) - buf->used); > + (sizeof(buf->buf) - buf->used) < dc->maxread ? > + (sizeof(buf->buf) - buf->used) : dc->maxread); > if (r < 0) { > if (errno == EINTR) continue; > if (errno == EWOULDBLOCK) break; > @@ -258,7 +259,11 @@ static void datacopier_readable(libxl__egc *egc, libxl__ev_fd *ev, > } > buf->used += r; > dc->used += r; > + dc->maxread -= r; > assert(buf->used <= sizeof(buf->buf)); > + assert(dc->maxread >= 0); > + if (dc->maxread == 0) > + break; We can call libxl__ev_fd_deregister() here, and no need to touch datacopier_check_state(). Otherwise, datacopier_readable() may be called again, and read() returns 0. And then libxl__ev_fd_deregister() is called. Thanks Wen Congyang > } > datacopier_check_state(egc, dc); > } > diff --git a/tools/libxl/libxl_bootloader.c b/tools/libxl/libxl_bootloader.c > index 79947d4..1503101 100644 > --- a/tools/libxl/libxl_bootloader.c > +++ b/tools/libxl/libxl_bootloader.c > @@ -516,6 +516,7 @@ static void bootloader_gotptys(libxl__egc *egc, libxl__openpty_state *op) > > bl->keystrokes.ao = ao; > bl->keystrokes.maxsz = BOOTLOADER_BUF_OUT; > + bl->keystrokes.maxread = INT_MAX; > bl->keystrokes.copywhat = > GCSPRINTF("bootloader input for domain %"PRIu32, bl->domid); > bl->keystrokes.callback = bootloader_keystrokes_copyfail; > @@ -527,6 +528,7 @@ static void bootloader_gotptys(libxl__egc *egc, libxl__openpty_state *op) > > bl->display.ao = ao; > bl->display.maxsz = BOOTLOADER_BUF_IN; > + bl->display.maxread = INT_MAX; > bl->display.copywhat = > GCSPRINTF("bootloader output for domain %"PRIu32, bl->domid); > bl->display.callback = bootloader_display_copyfail; > diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c > index 0dfdb08..2f74341 100644 > --- a/tools/libxl/libxl_dom.c > +++ b/tools/libxl/libxl_dom.c > @@ -1717,6 +1717,7 @@ void libxl__domain_save_device_model(libxl__egc *egc, > dc->readfd = -1; > dc->writefd = fd; > dc->maxsz = INT_MAX; > + dc->maxread = INT_MAX; > dc->copywhat = GCSPRINTF("qemu save file for domain %"PRIu32, dss->domid); > dc->writewhat = "save/migration stream"; > dc->callback = save_device_model_datacopier_done; > diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h > index 03e9978..d93a6ee 100644 > --- a/tools/libxl/libxl_internal.h > +++ b/tools/libxl/libxl_internal.h > @@ -2425,6 +2425,7 @@ struct libxl__datacopier_state { > libxl__ao *ao; > int readfd, writefd; > ssize_t maxsz; > + ssize_t maxread; > const char *copywhat, *readwhat, *writewhat; /* for error msgs */ > FILE *log; /* gets a copy of everything */ > libxl__datacopier_callback *callback; >