Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
On (Wed) 15 Jul 2015 [23:44:52], Nils Carlson wrote: On Mon, 13 Jul 2015, Nils Carlson wrote: On Mon, 13 Jul 2015, Amit Shah wrote: snip Also, returning TRUE there isn't right - if the connection ends, we should return FALSE. I agree that this seems reasonable. I will change it and re-test. I had a closer look, and it seems always returning true is intentional here, the called function, tcp_chr_disconnect(chr), handles the deregistration from handlers. If we were to return FALSE we would be duplicating work and possibly breaking things. Not sure how. Anyway, can you please start a new thread, with the author and reviewers of the patch CC'ed, so they can chime in as well? Amit
Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
On Thu, 16 Jul 2015, Amit Shah wrote: On (Wed) 15 Jul 2015 [23:44:52], Nils Carlson wrote: On Mon, 13 Jul 2015, Nils Carlson wrote: On Mon, 13 Jul 2015, Amit Shah wrote: snip Also, returning TRUE there isn't right - if the connection ends, we should return FALSE. I agree that this seems reasonable. I will change it and re-test. I had a closer look, and it seems always returning true is intentional here, the called function, tcp_chr_disconnect(chr), handles the deregistration from handlers. If we were to return FALSE we would be duplicating work and possibly breaking things. Not sure how. Anyway, can you please start a new thread, with the author and reviewers of the patch CC'ed, so they can chime in as well? The authors and reviewers of which patch exactly? The fix for windows which broke cloudstack was done in 812c1057. The returning TRUE everywhere was done in commit cdbf6e16 by Paolo Bonzini, CC:d above. I don't think there was anything wrong with either patch, the former one simply broken a strange behaviour CloudStack was relying on which I would say is dubious (fire and forget messaging.) /Nils
Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
On (Thu) 16 Jul 2015 [10:11:04], Nils Carlson wrote: On Thu, 16 Jul 2015, Amit Shah wrote: On (Wed) 15 Jul 2015 [23:44:52], Nils Carlson wrote: On Mon, 13 Jul 2015, Nils Carlson wrote: On Mon, 13 Jul 2015, Amit Shah wrote: snip Also, returning TRUE there isn't right - if the connection ends, we should return FALSE. I agree that this seems reasonable. I will change it and re-test. I had a closer look, and it seems always returning true is intentional here, the called function, tcp_chr_disconnect(chr), handles the deregistration from handlers. If we were to return FALSE we would be duplicating work and possibly breaking things. Not sure how. Anyway, can you please start a new thread, with the author and reviewers of the patch CC'ed, so they can chime in as well? The authors and reviewers of which patch exactly? The fix for windows which broke cloudstack was done in 812c1057. Yea, the author of this patch. Also, I meant the return TRUE in this patch, not the one Paolo added. The returning TRUE everywhere was done in commit cdbf6e16 by Paolo Bonzini, CC:d above. I don't think there was anything wrong with either patch, the former one simply broken a strange behaviour CloudStack was relying on which I would say is dubious (fire and forget messaging.) There need not be anything wrong with a previous patch; but just because someone touched the area recently, they might have more context, and even help in spotting the bug. Amit
Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
On Mon, 13 Jul 2015, Nils Carlson wrote: On Mon, 13 Jul 2015, Amit Shah wrote: snip Also, returning TRUE there isn't right - if the connection ends, we should return FALSE. I agree that this seems reasonable. I will change it and re-test. I had a closer look, and it seems always returning true is intentional here, the called function, tcp_chr_disconnect(chr), handles the deregistration from handlers. If we were to return FALSE we would be duplicating work and possibly breaking things. Nils Amit
Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
On (Mon) 13 Jul 2015 [12:15:22], Paolo Bonzini wrote:
On 13/07/2015 10:13, pyssl...@ludd.ltu.se wrote:
Commit 812c1057 introduced HUP detection on unix and tcp sockets prior
to a read in tcp_chr_read. This unfortunately broke CloudStack 4.2
which relied on the old behaviour where data on a socket was readable
even if a HUP was present.
On Linux a working solution seems to be to simply check the HUP after
reading available data, while keeping the original behaviour for windows.
There is then a divergence in behaviour for the two platforms, but this
seems better than breaking a whole software stack.
There is no need to do something special on Windows, I think. You can
unconditionally check G_IO_HUP after reading. One nit:
-if (size == 0) {
+if (size == 0 || (size 0 cond G_IO_HUP)) {
Please put (cond G_IO_HUP) within parentheses.
Also, returning TRUE there isn't right - if the connection ends, we
should return FALSE.
Amit
Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
On 13/07/2015 10:13, pyssl...@ludd.ltu.se wrote:
Commit 812c1057 introduced HUP detection on unix and tcp sockets prior
to a read in tcp_chr_read. This unfortunately broke CloudStack 4.2
which relied on the old behaviour where data on a socket was readable
even if a HUP was present.
On Linux a working solution seems to be to simply check the HUP after
reading available data, while keeping the original behaviour for windows.
There is then a divergence in behaviour for the two platforms, but this
seems better than breaking a whole software stack.
There is no need to do something special on Windows, I think. You can
unconditionally check G_IO_HUP after reading. One nit:
-if (size == 0) {
+if (size == 0 || (size 0 cond G_IO_HUP)) {
Please put (cond G_IO_HUP) within parentheses.
Please
Re: [Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
On Mon, 13 Jul 2015, Amit Shah wrote:
On (Mon) 13 Jul 2015 [12:15:22], Paolo Bonzini wrote:
On 13/07/2015 10:13, pyssl...@ludd.ltu.se wrote:
Commit 812c1057 introduced HUP detection on unix and tcp sockets prior
to a read in tcp_chr_read. This unfortunately broke CloudStack 4.2
which relied on the old behaviour where data on a socket was readable
even if a HUP was present.
On Linux a working solution seems to be to simply check the HUP after
reading available data, while keeping the original behaviour for windows.
There is then a divergence in behaviour for the two platforms, but this
seems better than breaking a whole software stack.
There is no need to do something special on Windows, I think. You can
unconditionally check G_IO_HUP after reading. One nit:
-if (size == 0) {
+if (size == 0 || (size 0 cond G_IO_HUP)) {
Please put (cond G_IO_HUP) within parentheses.
Also, returning TRUE there isn't right - if the connection ends, we
should return FALSE.
I agree that this seems reasonable. I will change it and re-test.
Amit
[Qemu-devel] [PATCH] qemu-char: Fix missed data on unix socket
From: Nils Carlson pyssl...@ludd.ltu.se
Commit 812c1057 introduced HUP detection on unix and tcp sockets prior
to a read in tcp_chr_read. This unfortunately broke CloudStack 4.2
which relied on the old behaviour where data on a socket was readable
even if a HUP was present.
On Linux a working solution seems to be to simply check the HUP after
reading available data, while keeping the original behaviour for windows.
There is then a divergence in behaviour for the two platforms, but this
seems better than breaking a whole software stack.
Signed-off-by: Nils Carlson pyssl...@ludd.ltu.se
---
qemu-char.c |4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/qemu-char.c b/qemu-char.c
index 617e034..cfd9b70 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2847,11 +2847,13 @@ static gboolean tcp_chr_read(GIOChannel *chan,
GIOCondition cond, void *opaque)
uint8_t buf[READ_BUF_LEN];
int len, size;
+#ifdef _WIN32
if (cond G_IO_HUP) {
/* connection closed */
tcp_chr_disconnect(chr);
return TRUE;
}
+#endif
if (!s-connected || s-max_size = 0) {
return TRUE;
@@ -2860,7 +2862,7 @@ static gboolean tcp_chr_read(GIOChannel *chan,
GIOCondition cond, void *opaque)
if (len s-max_size)
len = s-max_size;
size = tcp_chr_recv(chr, (void *)buf, len);
-if (size == 0) {
+if (size == 0 || (size 0 cond G_IO_HUP)) {
/* connection closed */
tcp_chr_disconnect(chr);
} else if (size 0) {
--
1.7.10.4
