transactions run always under the BQL lock, so they are all in the global state API.
Signed-off-by: Emanuele Giuseppe Esposito <[email protected]> --- include/qemu/transactions.h | 24 ++++++++++++++++++++++++ util/transactions.c | 4 ++++ 2 files changed, 28 insertions(+) diff --git a/include/qemu/transactions.h b/include/qemu/transactions.h index 92c5965235..f4a7c473fa 100644 --- a/include/qemu/transactions.h +++ b/include/qemu/transactions.h @@ -37,6 +37,29 @@ #define QEMU_TRANSACTIONS_H #include <gmodule.h> +#include "qemu/main-loop.h" + +/* + * Global state (GS) API. These functions run under the BQL lock. + * + * If a function modifies the graph, it also uses drain and/or + * aio_context_acquire/release to be sure it has unique access. + * aio_context locking is needed together with BQL because of + * the thread-safe I/O API that concurrently runs and accesses + * the graph without the BQL. + * + * It is important to note that not all of these functions are + * necessarily limited to running under the BQL, but they would + * require additional auditing and may small thread-safety changes + * to move them into the I/O API. Often it's not worth doing that + * work since the APIs are only used with the BQL held at the + * moment, so they have been placed in the GS API (for now). + * + * All functions and function pointers in this header must use + * this assertion: + * g_assert(qemu_in_main_thread()); + * to catch when they are accidentally called without the BQL. + */ typedef struct TransactionActionDrv { void (*abort)(void *opaque); @@ -53,6 +76,7 @@ void tran_commit(Transaction *tran); static inline void tran_finalize(Transaction *tran, int ret) { + g_assert(qemu_in_main_thread()); if (ret < 0) { tran_abort(tran); } else { diff --git a/util/transactions.c b/util/transactions.c index d0bc9a3e73..20c3dafdb8 100644 --- a/util/transactions.c +++ b/util/transactions.c @@ -23,6 +23,7 @@ #include "qemu/osdep.h" #include "qemu/transactions.h" +#include "qemu/main-loop.h" #include "qemu/queue.h" typedef struct TransactionAction { @@ -47,6 +48,7 @@ Transaction *tran_new(void) void tran_add(Transaction *tran, TransactionActionDrv *drv, void *opaque) { TransactionAction *act; + g_assert(qemu_in_main_thread()); act = g_new(TransactionAction, 1); *act = (TransactionAction) { @@ -60,6 +62,7 @@ void tran_add(Transaction *tran, TransactionActionDrv *drv, void *opaque) void tran_abort(Transaction *tran) { TransactionAction *act, *next; + g_assert(qemu_in_main_thread()); QSLIST_FOREACH_SAFE(act, &tran->actions, entry, next) { if (act->drv->abort) { @@ -79,6 +82,7 @@ void tran_abort(Transaction *tran) void tran_commit(Transaction *tran) { TransactionAction *act, *next; + g_assert(qemu_in_main_thread()); QSLIST_FOREACH_SAFE(act, &tran->actions, entry, next) { if (act->drv->commit) { -- 2.27.0
