From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40234) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXPY9-0003v0-OJ for qemu-devel@nongnu.org; Mon, 16 Mar 2015 03:34:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YXPY0-0004sd-VT for qemu-devel@nongnu.org; Mon, 16 Mar 2015 03:34:57 -0400 Received: from mail-wg0-x236.google.com ([2a00:1450:400c:c00::236]:33795) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXPY0-0004sT-Nj for qemu-devel@nongnu.org; Mon, 16 Mar 2015 03:34:48 -0400 Received: by wggv3 with SMTP id v3so32353429wgg.1 for ; Mon, 16 Mar 2015 00:34:48 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <55068793.8020005@redhat.com> Date: Mon, 16 Mar 2015 08:34:43 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1426483910-24597-1-git-send-email-famz@redhat.com> <1426483910-24597-4-git-send-email-famz@redhat.com> In-Reply-To: <1426483910-24597-4-git-send-email-famz@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3 3/4] exec: Notify cpu_register_map_client caller if the bounce buffer is available List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , qemu-devel@nongnu.org On 16/03/2015 06:31, Fam Zheng wrote: > The caller's workflow is like > > if (!address_space_map()) { > ... > cpu_register_map_client(); > } > > If bounce buffer became available after address_space_map() but before > cpu_register_map_client(), the caller could miss it and has to wait for the > next bounce buffer notify, which may never happen in the worse case. > > Just notify the list in cpu_register_map_client(). > > Signed-off-by: Fam Zheng > --- > exec.c | 22 +++++++++++++++------- > 1 file changed, 15 insertions(+), 7 deletions(-) > > diff --git a/exec.c b/exec.c > index 3e54580..20381a0 100644 > --- a/exec.c > +++ b/exec.c > @@ -2489,6 +2489,17 @@ QemuMutex map_client_list_lock; > static QLIST_HEAD(map_client_list, MapClient) map_client_list > = QLIST_HEAD_INITIALIZER(map_client_list); > > +static void cpu_notify_map_clients_unlocked(void) > +{ > + MapClient *client; > + > + while (!QLIST_EMPTY(&map_client_list)) { > + client = QLIST_FIRST(&map_client_list); > + client->callback(client->opaque); > + cpu_unregister_map_client(client); > + } > +} Isn't the convention to call these functions "*_locked" (e.g. timer_mod_ns_locked, monitor_flush_locked, cpu_get_clock_locked)? Otherwise okay. Paolo > + > void *cpu_register_map_client(void *opaque, void (*callback)(void *opaque)) > { > MapClient *client = g_malloc(sizeof(*client)); > @@ -2497,6 +2508,9 @@ void *cpu_register_map_client(void *opaque, void (*callback)(void *opaque)) > client->opaque = opaque; > client->callback = callback; > QLIST_INSERT_HEAD(&map_client_list, client, link); > + if (!atomic_read(&bounce.in_use)) { > + cpu_notify_map_clients_unlocked(); > + } > qemu_mutex_unlock(&map_client_list_lock); > return client; > } > @@ -2521,14 +2535,8 @@ static void cpu_unregister_map_client(void *_client) > > static void cpu_notify_map_clients(void) > { > - MapClient *client; > - > qemu_mutex_lock(&map_client_list_lock); > - while (!QLIST_EMPTY(&map_client_list)) { > - client = QLIST_FIRST(&map_client_list); > - client->callback(client->opaque); > - cpu_unregister_map_client(client); > - } > + cpu_notify_map_clients_unlocked(); > qemu_mutex_unlock(&map_client_list_lock); > } > >