[PATCH v2 0/3] tools: Fixes for 4.4

[PATCH v2 0/3] tools: Fixes for 4.4

[Ian Jackson]

I think these three bugfixes are clear 4.4 material.

 a 1/3 libxl: events: Pass correct nfds to poll
 a 2/3 xl: Free optdata_begin when saving domain config
 a 3/3 xenstore: xs_suspend_evtchn_port: always free portstr

They have all been acked by Ian Campbell.

Thanks,
Ian.

[PATCH 1/3] libxl: events: Pass correct nfds to poll

[Ian Jackson]

libxl_event.c:eventloop_iteration would pass the allocated pollfds
array size, rather than the used size, to poll (and to
afterpoll_internal).

The effect is that if the number of fds to poll on reduces, libxl will
poll on stale entries.  Because of the way the return value from poll
is processed these stale entries are often harmless because any events
coming back from poll ignored by libxl.  However, it could cause
malfunctions:

It could result in unwanted SIGTTIN/SIGTTOU/SIGPIPE, for example, if
the fd has been reused to refer to an object which can generate those
signals.  Alternatively, it could result in libxl spinning if the
stale entry refers to an fd which happens now to be ready for the
previously-requested operation.

I have tested this with a localhost migration and inspected the strace
output.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Jim Fehlig <jfehlig@suse.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
---
 tools/libxl/libxl_event.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/tools/libxl/libxl_event.c b/tools/libxl/libxl_event.c
index bdef7ac..1c48fee 100644
--- a/tools/libxl/libxl_event.c
+++ b/tools/libxl/libxl_event.c
@@ -1386,7 +1386,7 @@ static int eventloop_iteration(libxl__egc *egc, libxl__poller *poller) {
      * can unlock it when it polls.
      */
     EGC_GC;
-    int rc;
+    int rc, nfds;
     struct timeval now;
     
     rc = libxl__gettimeofday(gc, &now);
@@ -1395,7 +1395,7 @@ static int eventloop_iteration(libxl__egc *egc, libxl__poller *poller) {
     int timeout;
 
     for (;;) {
-        int nfds = poller->fd_polls_allocd;
+        nfds = poller->fd_polls_allocd;
         timeout = -1;
         rc = beforepoll_internal(gc, poller, &nfds, poller->fd_polls,
                                  &timeout, now);
@@ -1413,7 +1413,7 @@ static int eventloop_iteration(libxl__egc *egc, libxl__poller *poller) {
     }
 
     CTX_UNLOCK;
-    rc = poll(poller->fd_polls, poller->fd_polls_allocd, timeout);
+    rc = poll(poller->fd_polls, nfds, timeout);
     CTX_LOCK;
 
     if (rc < 0) {
@@ -1428,8 +1428,7 @@ static int eventloop_iteration(libxl__egc *egc, libxl__poller *poller) {
     rc = libxl__gettimeofday(gc, &now);
     if (rc) goto out;
 
-    afterpoll_internal(egc, poller,
-                       poller->fd_polls_allocd, poller->fd_polls, now);
+    afterpoll_internal(egc, poller, nfds, poller->fd_polls, now);
 
     rc = 0;
  out:
-- 
1.7.10.4

[PATCH 2/3] xl: Free optdata_begin when saving domain config

[Ian Jackson]

This makes valgrind a bit happier.

It is also
Coverity-CID: 1055903

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Ian Campbell <Ian.Campbell@citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>
---
 tools/libxl/xl_cmdimpl.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index d93e01b..aff6f90 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -3442,6 +3442,8 @@ static void save_domain_core_writeconfig(int fd, const char *source,
                      ctx, fd, optdata_begin, hdr.optional_data_len,
                      source, "header"));
 
+    free(optdata_begin);
+
     fprintf(stderr, "Saving to %s new xl format (info"
             " 0x%"PRIx32"/0x%"PRIx32"/%"PRIu32")\n",
             source, hdr.mandatory_flags, hdr.optional_flags,
-- 
1.7.10.4

[PATCH 3/3] xenstore: xs_suspend_evtchn_port: always free portstr

[Ian Jackson]

If portstr!=NULL but plen==0 this function would leak portstr.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <Ian.Campbell@citrix.com>

---
v2: Fix whitespace error.
---
 tools/xenstore/xs.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/xenstore/xs.c b/tools/xenstore/xs.c
index a636498..dd03a85 100644
--- a/tools/xenstore/xs.c
+++ b/tools/xenstore/xs.c
@@ -1095,12 +1095,15 @@ int xs_suspend_evtchn_port(int domid)
     portstr = xs_read(xs, XBT_NULL, path, &plen);
     xs_daemon_close(xs);
 
-    if (!portstr || !plen)
-        return -1;
+    if (!portstr || !plen) {
+        port = -1;
+        goto out;
+    }
 
     port = atoi(portstr);
-    free(portstr);
 
+out:
+    free(portstr);
     return port;
 }
 
-- 
1.7.10.4

Re: [PATCH v2 0/3] tools: Fixes for 4.4

[George Dunlap]

On 01/21/2014 06:45 PM, Ian Jackson wrote:
> I think these three bugfixes are clear 4.4 material.
>
>   a 1/3 libxl: events: Pass correct nfds to poll
>   a 2/3 xl: Free optdata_begin when saving domain config
>   a 3/3 xenstore: xs_suspend_evtchn_port: always free portstr
>
> They have all been acked by Ian Campbell.

All three:

Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>

Re: [PATCH v2 0/3] tools: Fixes for 4.4

[Ian Campbell]

On Mon, 2014-01-27 at 12:14 +0000, George Dunlap wrote:
> On 01/21/2014 06:45 PM, Ian Jackson wrote:
> > I think these three bugfixes are clear 4.4 material.
> >
> >   a 1/3 libxl: events: Pass correct nfds to poll
> >   a 2/3 xl: Free optdata_begin when saving domain config
> >   a 3/3 xenstore: xs_suspend_evtchn_port: always free portstr
> >
> > They have all been acked by Ian Campbell.
> 
> All three:
> 
> Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>

Applied.