From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42152) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXPhn-0000yJ-5Q for qemu-devel@nongnu.org; Mon, 16 Mar 2015 03:44:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YXPhj-00087h-0s for qemu-devel@nongnu.org; Mon, 16 Mar 2015 03:44:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47993) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YXPhi-00087b-Rl for qemu-devel@nongnu.org; Mon, 16 Mar 2015 03:44:50 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (Postfix) with ESMTPS id 77F61C6A06 for ; Mon, 16 Mar 2015 07:44:50 +0000 (UTC) Date: Mon, 16 Mar 2015 15:44:47 +0800 From: Fam Zheng Message-ID: <20150316074447.GD15098@ad.nay.redhat.com> References: <1426483910-24597-1-git-send-email-famz@redhat.com> <1426483910-24597-4-git-send-email-famz@redhat.com> <55068793.8020005@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55068793.8020005@redhat.com> 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: Paolo Bonzini Cc: qemu-devel@nongnu.org On Mon, 03/16 08:34, Paolo Bonzini wrote: > > > 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)? Exactly, will rename. Thanks. Fam > > 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); > > } > > > >