qemu/stubs/monitor.c

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#include "qemu/osdep.h"
2016-03-14 11:01:28 +03:00
#include "qapi/error.h"
#include "qapi/qapi-emit-events.h"
#include "monitor/monitor.h"
monitor: Fix unsafe sharing of @cur_mon among threads @cur_mon is null unless the main thread is running monitor code, either HMP code within monitor_read(), or QMP code within monitor_qmp_dispatch(). Use of @cur_mon outside the main thread is therefore unsafe. Most of its uses are in monitor command handlers. These run in the main thread. However, there are also uses hiding elsewhere, such as in error_vprintf(), and thus error_report(), making these functions unsafe outside the main thread. No such unsafe uses are known at this time. Regardless, this is an unnecessary trap. It's an ancient trap, though. More recently, commit cf869d53172 "qmp: support out-of-band (oob) execution" spiced things up: the monitor I/O thread assigns to @cur_mon when executing commands out-of-band. Having two threads save, set and restore @cur_mon without synchronization is definitely unsafe. We can end up with @cur_mon null while the main thread runs monitor code, or non-null while it runs non-monitor code. We could fix this by making the I/O thread not mess with @cur_mon, but that would leave the trap armed and ready. Instead, make @cur_mon thread-local. It's now reliably null unless the thread is running monitor code. Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> [peterx: update subject and commit message written by Markus] Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20180720033451.32710-1-peterx@redhat.com>
2018-07-20 06:34:51 +03:00
__thread Monitor *cur_mon;
int monitor_vprintf(Monitor *mon, const char *fmt, va_list ap)
{
abort();
}
int monitor_get_fd(Monitor *mon, const char *name, Error **errp)
{
error_setg(errp, "only QEMU supports file descriptor passing");
return -1;
}
void monitor_init_qmp(Chardev *chr, bool pretty)
{
}
void monitor_init_hmp(Chardev *chr, bool use_readline)
{
}
qapi: Eliminate indirection through qmp_event_get_func_emit() The qapi_event_send_FOO() functions emit events like this: QMPEventFuncEmit emit; emit = qmp_event_get_func_emit(); if (!emit) { return; } qmp = qmp_event_build_dict("FOO"); [put event arguments into @qmp...] emit(QAPI_EVENT_FOO, qmp); The value of qmp_event_get_func_emit() depends only on the program: * In qemu-system-FOO, it's always monitor_qapi_event_queue. * In tests/test-qmp-event, it's always event_test_emit. * In all other programs, it's always null. This is exactly the kind of dependence the linker is supposed to resolve; we don't actually need an indirection. Note that things would fall apart if we linked more than one QAPI schema into a single program: each set of qapi_event_send_FOO() uses its own event enumeration, yet they share a single emit function. Which takes the event enumeration as an argument. Which one if there's more than one? More seriously: how does this work even now? qemu-system-FOO wants QAPIEvent, and passes a function taking that to qmp_event_set_func_emit(). test-qmp-event wants test_QAPIEvent, and passes a function taking that to qmp_event_set_func_emit(). It works by type trickery, of course: typedef void (*QMPEventFuncEmit)(unsigned event, QDict *dict); void qmp_event_set_func_emit(QMPEventFuncEmit emit); QMPEventFuncEmit qmp_event_get_func_emit(void); We use unsigned instead of the enumeration type. Relies on both enumerations boiling down to unsigned, which happens to be true for the compilers we use. Clean this up as follows: * Generate qapi_event_send_FOO() that call PREFIX_qapi_event_emit() instead of the value of qmp_event_set_func_emit(). * Generate a prototype for PREFIX_qapi_event_emit() into qapi-events.h. * PREFIX_ is empty for qapi/qapi-schema.json, and test_ for tests/qapi-schema/qapi-schema-test.json. It's qga_ for qga/qapi-schema.json, and doc-good- for tests/qapi-schema/doc-good.json, but those don't define any events. * Rename monitor_qapi_event_queue() to qapi_event_emit() instead of passing it to qmp_event_set_func_emit(). This takes care of qemu-system-FOO. * Rename event_test_emit() to test_qapi_event_emit() instead of passing it to qmp_event_set_func_emit(). This takes care of tests/test-qmp-event. * Add a qapi_event_emit() that does nothing to stubs/monitor.c. This takes care of all other programs that link code emitting QMP events. * Drop qmp_event_set_func_emit(), qmp_event_get_func_emit(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20181218182234.28876-3-armbru@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> [Commit message typos fixed]
2018-12-18 21:22:21 +03:00
void qapi_event_emit(QAPIEvent event, QDict *qdict)
{
}