Re: [PATCH 01/22] Prevent abortion on multiple VCPU kicks
On 01/27/2011 03:09 PM, Jan Kiszka wrote: If we call qemu_cpu_kick more than once before the target was able to process the signal, pthread_kill will fail, and qemu will abort. Prevent this by avoiding the redundant signal. Doesn't fit with the manual page (or with the idea that signals are asynchronous): NAME pthread_kill - send a signal to a thread ... ERRORS ESRCH No thread with the ID thread could be found. EINVAL An invalid signal was specified. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 01/22] Prevent abortion on multiple VCPU kicks
On 2011-01-31 10:44, Avi Kivity wrote: On 01/27/2011 03:09 PM, Jan Kiszka wrote: If we call qemu_cpu_kick more than once before the target was able to process the signal, pthread_kill will fail, and qemu will abort. Prevent this by avoiding the redundant signal. Doesn't fit with the manual page (or with the idea that signals are asynchronous): NAME pthread_kill - send a signal to a thread ... ERRORS ESRCH No thread with the ID thread could be found. EINVAL An invalid signal was specified. Valid remark, but I was receiving EAGAIN for blocked RT signals. Don't know if this is Linux-specific. A quick glance at the man pages did not reveal if this is allowed or at least gray area. However, even when selectively ignoring this, it's more efficient to catch the redundant signaling in user space. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH 01/22] Prevent abortion on multiple VCPU kicks
On 01/31/2011 01:19 PM, Jan Kiszka wrote:
On 2011-01-31 10:44, Avi Kivity wrote:
On 01/27/2011 03:09 PM, Jan Kiszka wrote:
If we call qemu_cpu_kick more than once before the target was able to
process the signal, pthread_kill will fail, and qemu will abort. Prevent
this by avoiding the redundant signal.
Doesn't fit with the manual page (or with the idea that signals are
asynchronous):
NAME
pthread_kill - send a signal to a thread
...
ERRORS
ESRCH No thread with the ID thread could be found.
EINVAL An invalid signal was specified.
Valid remark, but I was receiving EAGAIN for blocked RT signals. Don't
know if this is Linux-specific. A quick glance at the man pages did not
reveal if this is allowed or at least gray area.
} else if (!is_si_special(info)) {
if (sig = SIGRTMIN info-si_code != SI_USER) {
/*
* Queue overflow, abort. We may abort if the
* signal was rt and sent by user using something
* other than kill().
*/
trace_signal_overflow_fail(sig, group, info);
return -EAGAIN;
}
However, even when selectively ignoring this, it's more efficient to
catch the redundant signaling in user space.
Yes.
--
error compiling committee.c: too many arguments to function
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[PATCH 01/22] Prevent abortion on multiple VCPU kicks
If we call qemu_cpu_kick more than once before the target was able to
process the signal, pthread_kill will fail, and qemu will abort. Prevent
this by avoiding the redundant signal.
This logic can be found in qemu-kvm as well.
Signed-off-by: Jan Kiszka jan.kis...@siemens.com
---
cpu-defs.h |1 +
cpus.c |6 +-
2 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/cpu-defs.h b/cpu-defs.h
index 8d4bf86..db809ed 100644
--- a/cpu-defs.h
+++ b/cpu-defs.h
@@ -205,6 +205,7 @@ typedef struct CPUWatchpoint {
uint32_t stopped; /* Artificially stopped */\
struct QemuThread *thread; \
struct QemuCond *halt_cond; \
+int thread_kicked; \
struct qemu_work_item *queued_work_first, *queued_work_last;\
const char *cpu_model_str; \
struct KVMState *kvm_state; \
diff --git a/cpus.c b/cpus.c
index 4c9928e..ab6e40e 100644
--- a/cpus.c
+++ b/cpus.c
@@ -481,6 +481,7 @@ static void qemu_wait_io_event_common(CPUState *env)
qemu_cond_signal(qemu_pause_cond);
}
flush_queued_work(env);
+env-thread_kicked = false;
}
static void qemu_tcg_wait_io_event(void)
@@ -648,7 +649,10 @@ void qemu_cpu_kick(void *_env)
{
CPUState *env = _env;
qemu_cond_broadcast(env-halt_cond);
-qemu_thread_signal(env-thread, SIG_IPI);
+if (!env-thread_kicked) {
+qemu_thread_signal(env-thread, SIG_IPI);
+env-thread_kicked = true;
+}
}
int qemu_cpu_self(void *_env)
--
1.7.1
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