From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37310) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vu8p9-0008SD-HX for qemu-devel@nongnu.org; Fri, 20 Dec 2013 17:45:44 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Vu8p4-0004IJ-G4 for qemu-devel@nongnu.org; Fri, 20 Dec 2013 17:45:39 -0500 Sender: Paolo Bonzini From: Paolo Bonzini Date: Fri, 20 Dec 2013 23:45:24 +0100 Message-Id: <1387579525-6224-2-git-send-email-pbonzini@redhat.com> In-Reply-To: <1387579525-6224-1-git-send-email-pbonzini@redhat.com> References: <1387579525-6224-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PULL 1/2] block/iscsi: use a bh to schedule co reentrance List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Lieven , qemu-stable@nongnu.org From: Peter Lieven this fixes a potential segfault and performance regression. If the coroutine is reentered directly in the iscsi_co_generic_cb iscsi_process_{read,write} are interrupted and reentered any time later. One the one hand this could happen after an iscsi_close where the iscsi context is already gone (segfault). On the other hand this limits the number of processed callbacks in each aio_dispatch to one (potential performance regression). Cc: qemu-stable@nongnu.org Signed-off-by: Peter Lieven Signed-off-by: Paolo Bonzini --- block/iscsi.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/block/iscsi.c b/block/iscsi.c index fa69408..b0e6eea 100644 --- a/block/iscsi.c +++ b/block/iscsi.c @@ -68,6 +68,7 @@ typedef struct IscsiTask { int do_retry; struct scsi_task *task; Coroutine *co; + QEMUBH *bh; } IscsiTask; typedef struct IscsiAIOCB { @@ -123,6 +124,13 @@ iscsi_schedule_bh(IscsiAIOCB *acb) qemu_bh_schedule(acb->bh); } +static void iscsi_co_generic_bh_cb(void *opaque) +{ + struct IscsiTask *iTask = opaque; + qemu_bh_delete(iTask->bh); + qemu_coroutine_enter(iTask->co, NULL); +} + static void iscsi_co_generic_cb(struct iscsi_context *iscsi, int status, void *command_data, void *opaque) @@ -147,7 +155,8 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status, out: if (iTask->co) { - qemu_coroutine_enter(iTask->co, NULL); + iTask->bh = qemu_bh_new(iscsi_co_generic_bh_cb, iTask); + qemu_bh_schedule(iTask->bh); } } -- 1.8.4.2