| Message ID | 4B190919.9040602@siemens.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Dec 04, 2009 at 02:05:29PM +0100, Jan Kiszka wrote: > This allows to suspend command interpretation and execution > synchronously, e.g. during migration. > > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> > --- > > monitor.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/monitor.c b/monitor.c > index 3286ba2..a3be1c8 100644 > --- a/monitor.c > +++ b/monitor.c > @@ -3418,7 +3418,7 @@ static int monitor_can_read(void *opaque) > { > Monitor *mon = opaque; > > - return (mon->suspend_cnt == 0) ? 128 : 0; > + return (mon->suspend_cnt == 0) ? 1 : 0; > } > > static void monitor_read(void *opaque, const uint8_t *buf, int size) FYI, this change seems to have broken the 'getfd' command in the monitor. Any attempt to use this command (in both text + json modes) is currently returning "No file descriptor supplied via SCM_RIGHTS" Reverting this change makes getfd work again for me. Strace of libvirtd shows it sending the command + FD in one message: sendmsg(18, {msg_name(0)=NULL, msg_iov(1)=[{"getfd fd-net2\r", 14}], msg_controllen=24, {cmsg_len=20, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {16}}, msg_flags=0}, 0) = 14 Strace of qemu shows that it receives the FD ok, but immediately closes it before finishing reading the actual monitor command with which it is associated: [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"g", 1}], msg_controllen=24, {cmsg_len=20, cmsg_level=SOL_SOCKET, cmsg_type=SCM_RIGHTS, {17}}, msg_flags=0}, 0) = 1 [pid 31941] close(17) = 0 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"e", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"t", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"f", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"d", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{" ", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"f", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"d", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"-", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"n", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"e", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"t", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"2", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 [pid 31941] recvmsg(16, {msg_name(0)=NULL, msg_iov(1)=[{"\r", 1}], msg_controllen=0, msg_flags=0}, 0) = 1 The QEMU code appears to be written to assume that it will recvmsg() a complete monitor command in one go + process that, because it closes the FD the moment the data from any recvmsg() is dealt with. Regards, Daniel
diff --git a/monitor.c b/monitor.c index 3286ba2..a3be1c8 100644 --- a/monitor.c +++ b/monitor.c @@ -3418,7 +3418,7 @@ static int monitor_can_read(void *opaque) { Monitor *mon = opaque; - return (mon->suspend_cnt == 0) ? 128 : 0; + return (mon->suspend_cnt == 0) ? 1 : 0; } static void monitor_read(void *opaque, const uint8_t *buf, int size)
This allows to suspend command interpretation and execution synchronously, e.g. during migration. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> --- monitor.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)