diff options
| -rw-r--r-- | util/fdmon-epoll.c | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/util/fdmon-epoll.c b/util/fdmon-epoll.c index e11a8a022e..1683aa1105 100644 --- a/util/fdmon-epoll.c +++ b/util/fdmon-epoll.c @@ -127,6 +127,8 @@ static bool fdmon_epoll_try_enable(AioContext *ctx) bool fdmon_epoll_try_upgrade(AioContext *ctx, unsigned npfd) { + bool ok; + if (ctx->epollfd < 0) { return false; } @@ -136,14 +138,23 @@ bool fdmon_epoll_try_upgrade(AioContext *ctx, unsigned npfd) return false; } - if (npfd >= EPOLL_ENABLE_THRESHOLD) { - if (fdmon_epoll_try_enable(ctx)) { - return true; - } else { - fdmon_epoll_disable(ctx); - } + if (npfd < EPOLL_ENABLE_THRESHOLD) { + return false; + } + + /* The list must not change while we add fds to epoll */ + if (!qemu_lockcnt_dec_if_lock(&ctx->list_lock)) { + return false; + } + + ok = fdmon_epoll_try_enable(ctx); + + qemu_lockcnt_inc_and_unlock(&ctx->list_lock); + + if (!ok) { + fdmon_epoll_disable(ctx); } - return false; + return ok; } void fdmon_epoll_setup(AioContext *ctx) |