Re: [libvirt] [PATCH v3 1/6] virfdstream: Check for thread error more frequently
On 06/05/2017 04:22 AM, Michal Privoznik wrote:
When the I/O thread quits (e.g. due to an I/O error, lseek()
error, whatever), any subsequent virFDStream API should return
error too. Moreover, when invoking stream event callback, we must
set the VIR_STREAM_EVENT_ERROR flag so that the callback knows
something bad happened.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/util/virfdstream.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/src/util/virfdstream.c b/src/util/virfdstream.c
index 7ee58be13..cd24757e6 100644
--- a/src/util/virfdstream.c
+++ b/src/util/virfdstream.c
@@ -312,6 +312,9 @@ static void virFDStreamEvent(int watch ATTRIBUTE_UNUSED,
return;
}
+ if (fdst->threadErr)
+ events |= VIR_STREAM_EVENT_ERROR;
+
This hunk almost feels separable... That is, it's updating the events
(VIR_STREAM_EVENT_ERROR) in the callback function feels different than
checking for threadErr more often, but I'll leave it up to you to decide
to split more or not.
cb = fdst->cb;
cbopaque = fdst->opaque;
ff = fdst->ff;
@@ -787,10 +790,10 @@ static int virFDStreamWrite(virStreamPtr st, const char *bytes,
size_t nbytes)
if (fdst->thread) {
char *buf;
- if (fdst->threadQuit) {
+ if (fdst->threadQuit || fdst->threadErr) {
virReportSystemError(EBADF, "%s",
_("cannot write to stream"));
Would this (and the subsequent similar check) possibly overwrite
something from a threadErr with this error message?
- return -1;
+ goto cleanup;
ouch, <sigh> and this is separable too technically....
}
if (VIR_ALLOC(msg) < 0 ||
@@ -866,7 +869,7 @@ static int virFDStreamRead(virStreamPtr st, char *bytes, size_t
nbytes)
virFDStreamMsgPtr msg = NULL;
while (!(msg = fdst->msg)) {
- if (fdst->threadQuit) {
+ if (fdst->threadQuit || fdst->threadErr) {
if (nbytes) {
virReportSystemError(EBADF, "%s",
_("stream is not open"));
@@ -959,6 +962,9 @@ virFDStreamSendHole(virStreamPtr st,
fdst->offset += length;
}
+ if (fdst->threadErr)
+ goto cleanup;
+
So it's interesting in these paths the threadErr check is done outside
the fdst->thread check which is different than the virFDStreamRead and
Write API's.
if (fdst->thread) {
/* Things are a bit complicated here. If FDStream is in a
* read mode, then if the message at the queue head is
@@ -1018,6 +1024,9 @@ virFDStreamInData(virStreamPtr st,
virObjectLock(fdst);
+ if (fdst->threadErr)
+ goto cleanup;
+
This one in particular because threadQuit is checked in the subsequent
code similar to virFDStreamRead made me ponder a bit more, but I'm not
sure I could come to a conclusion...
I guess I'd want to see some consistency over when threadErr is checked
between the 4 functions or I'd wonder why 2 do things one way and 2 the
other. If they need to be different for a specific reason, then I
suppose more separation could be done or at least the commit message
indicate why they're different.
John
if (fdst->thread) {
virFDStreamMsgPtr msg;