Re: [libvirt] [PATCH 3/5] tests: avoid segfault if json monitor not present

2013-02-25 Thread Michal Privoznik 
On 23.02.2013 00:09, Eric Blake wrote:
 On a machine without json headers, I was seeing random segfaults
 from qemumonitorjsontest (about 90% of the runs on my particular
 machine).  The segfault was inside virClassIsDerivedFrom, which
 points to a case of a race leading to unreferencing a stale
 pointer to an object that had already been freed.  I also noticed
 that if I got the segfault, I was seeing messages such as:
 
 2013-02-22 16:12:37.504+: 19833: error : virNetSocketWriteWire:1361 : 
 Cannot write data: Bad file descriptor
 
 which is also evidence of deferencing a stale pointer.  I traced it
 to a race where qemuMonitorTestIO could execute late, after the
 main thread had already called qemuMonitorTestFree and called
 virNetSocketClose(test-client) but not clearing it out to NULL.
 Sure enough, after test-client has been closed, fd is -1, which
 causes an attempt to write to the socket to fail, which in turn
 triggers the error code of qemuMonitorTestIO that tries to re-close
 test-client.
 
 * tests/qemumonitortestutils.c (qemuMonitorTestIO): Don't attempt
 to free client again if test already quit.
 ---
  tests/qemumonitortestutils.c | 4 
  1 file changed, 4 insertions(+)
 
 diff --git a/tests/qemumonitortestutils.c b/tests/qemumonitortestutils.c
 index 1ed42ce..979623a 100644
 --- a/tests/qemumonitortestutils.c
 +++ b/tests/qemumonitortestutils.c
 @@ -214,6 +214,10 @@ static void qemuMonitorTestIO(virNetSocketPtr sock,
  bool err = false;
 
  virMutexLock(test-lock);
 +if (test-quit) {
 +virMutexUnlock(test-lock);
 +return;
 +}
  if (events  VIR_EVENT_HANDLE_WRITABLE) {
  ssize_t ret;
  if ((ret = virNetSocketWrite(sock,
 

ACK

Michal

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[libvirt] [PATCH 3/5] tests: avoid segfault if json monitor not present

2013-02-22 Thread Eric Blake 
On a machine without json headers, I was seeing random segfaults
from qemumonitorjsontest (about 90% of the runs on my particular
machine).  The segfault was inside virClassIsDerivedFrom, which
points to a case of a race leading to unreferencing a stale
pointer to an object that had already been freed.  I also noticed
that if I got the segfault, I was seeing messages such as:

2013-02-22 16:12:37.504+: 19833: error : virNetSocketWriteWire:1361 : 
Cannot write data: Bad file descriptor

which is also evidence of deferencing a stale pointer.  I traced it
to a race where qemuMonitorTestIO could execute late, after the
main thread had already called qemuMonitorTestFree and called
virNetSocketClose(test-client) but not clearing it out to NULL.
Sure enough, after test-client has been closed, fd is -1, which
causes an attempt to write to the socket to fail, which in turn
triggers the error code of qemuMonitorTestIO that tries to re-close
test-client.

* tests/qemumonitortestutils.c (qemuMonitorTestIO): Don't attempt
to free client again if test already quit.
---
 tests/qemumonitortestutils.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/tests/qemumonitortestutils.c b/tests/qemumonitortestutils.c
index 1ed42ce..979623a 100644
--- a/tests/qemumonitortestutils.c
+++ b/tests/qemumonitortestutils.c
@@ -214,6 +214,10 @@ static void qemuMonitorTestIO(virNetSocketPtr sock,
 bool err = false;

 virMutexLock(test-lock);
+if (test-quit) {
+virMutexUnlock(test-lock);
+return;
+}
 if (events  VIR_EVENT_HANDLE_WRITABLE) {
 ssize_t ret;
 if ((ret = virNetSocketWrite(sock,
-- 
1.8.1.2

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