Port-xen archive
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]
Re: xbd backend disconnection
On Mon, Sep 19, 2005 at 12:27:40AM +0200, Manuel Bouyer wrote:
> Hi,
> I've tried your patch and it doesn't work well: on my test system,
> a reboot of a dumU cause the xbdback driver to go catatonic. It seems that
> it never gets the CMSG_BLKIF_BE_DESTROY message, possibly because its
> CMSG_BLKIF_BE_DISCONNECT reply is missed. xend sends a CMSG_BLKIF_BE_CREATE
> anyway, and things start going wrong here.
> It's possible that not sending the reply message in-place cause this,
> and in fact all other users of ctrl_if_send_response() do a in-place
> reply.
OK, the problem was because you didn't initialize disconnect_rspid.
I also did a few more cleanups. The new patch is attached (against current)
--
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
NetBSD: 26 ans d'experience feront toujours la difference
--
Index: xbdback.c
===================================================================
RCS file: /cvsroot/src/sys/arch/xen/xen/xbdback.c,v
retrieving revision 1.15
diff -u -r1.15 xbdback.c
--- xbdback.c 10 Sep 2005 18:00:49 -0000 1.15
+++ xbdback.c 19 Sep 2005 21:40:21 -0000
@@ -75,7 +75,7 @@
struct xbdback_instance;
/* state of a xbdback instance */
-typedef enum {CONNECTED, DISCONNECTED} xbdback_state_t;
+typedef enum {CONNECTED, DISCONNECTING, DISCONNECTED} xbdback_state_t;
/*
* Since there are a variety of conditions that can block our I/O
@@ -94,7 +94,7 @@
SLIST_ENTRY(xbdback_instance) next;
domid_t domid; /* attached to this domain */
uint32_t handle; /* domain-specific handle */
- xbdback_state_t status;
+ volatile xbdback_state_t status;
/* parameters for the communication */
unsigned int evtchn;
paddr_t ma_ring;
@@ -102,6 +102,9 @@
blkif_ring_t *blk_ring;
BLKIF_RING_IDX resp_prod; /* our current reply index */
BLKIF_RING_IDX req_cons; /* our current request index */
+ /* disconnection must be postponed until all I/O is done */
+ volatile unsigned refcnt;
+ uint8_t disconnect_rspid; /* request id of the disconnect request */
/*
* State for I/O processing/coalescing follows; this has to
* live here instead of on the stack because of the
@@ -124,6 +127,16 @@
SLIST_HEAD(, xbd_vbd) vbds; /* list of virtual block devices */
};
+/* Manipulation of the above reference count. */
+/* XXXjld%panix.com@localhost: not MP-safe, and move the i386 asm elsewhere. */
+#define xbdi_get(xbdip) (++(xbdip)->refcnt)
+#define xbdi_put(xbdip) \
+do { \
+ __asm __volatile("decl %0" \
+ : "=m"((xbdip)->refcnt) : "m"((xbdip)->refcnt)); \
+ if (0 == (xbdip)->refcnt) \
+ xbdback_finish_disconnect(xbdip); \
+} while (/* CONSTCOND */ 0)
/* each xbdback instance has a list of vbds associated with it */
struct xbd_vbd {
@@ -202,6 +215,7 @@
static void xbdback_ctrlif_rx(ctrl_msg_t *, unsigned long);
static int xbdback_evthandler(void *);
+static void xbdback_finish_disconnect(struct xbdback_instance *);
static struct xbdback_instance *xbdif_lookup(domid_t, uint32_t);
static struct xbd_vbd * vbd_lookup(struct xbdback_instance *, blkif_vdev_t);
@@ -317,6 +331,8 @@
xbdi->domid = req->domid;
xbdi->handle = req->blkif_handle;
xbdi->status = DISCONNECTED;
+ xbdi->refcnt = 1;
+ xbdi->blk_ring = NULL;
SLIST_INIT(&xbdi->vbds);
SLIST_INSERT_HEAD(&xbdback_instances, xbdi, next);
@@ -333,10 +349,13 @@
req->status = BLKIF_BE_STATUS_INTERFACE_NOT_FOUND;
goto end;
}
- if (xbdi->status == CONNECTED) {
+ if (xbdi->status != DISCONNECTED) {
req->status = BLKIF_BE_STATUS_INTERFACE_CONNECTED;
goto end;
}
+ if (xbdi->blk_ring != NULL)
+ uvm_km_free(kernel_map, (vaddr_t)xbdi->blk_ring,
+ PAGE_SIZE, UVM_KMF_VAONLY);
SLIST_REMOVE(&xbdback_instances, xbdi, xbdback_instance, next);
free(xbdi, M_DEVBUF);
req->status = BLKIF_BE_STATUS_OKAY;
@@ -355,15 +374,20 @@
req->status = BLKIF_BE_STATUS_INTERFACE_NOT_FOUND;
goto end;
}
- if (xbdi->status == CONNECTED) {
+ if (xbdi->status != DISCONNECTED) {
req->status = BLKIF_BE_STATUS_INTERFACE_CONNECTED;
goto end;
}
- ring_addr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
- UVM_KMF_VAONLY);
- if (ring_addr == 0) {
- req->status = BLKIF_BE_STATUS_OUT_OF_MEMORY;
- goto end;
+ if (xbdi->blk_ring == NULL) {
+ ring_addr = uvm_km_alloc(kernel_map, PAGE_SIZE, 0,
+ UVM_KMF_VAONLY);
+ if (ring_addr == 0) {
+ req->status = BLKIF_BE_STATUS_OUT_OF_MEMORY;
+ goto end;
+ }
+ } else {
+ ring_addr = (vaddr_t)xbdi->blk_ring;
+ xbdi->blk_ring = NULL;
}
xbdi->ma_ring = req->shmem_frame << PAGE_SHIFT;
@@ -388,6 +412,7 @@
printf("xbd backend %d for domain %d using event channel %d\n",
xbdi->handle, xbdi->domid, xbdi->evtchn);
hypervisor_enable_event(xbdi->evtchn);
+ xbdi->status = CONNECTED;
req->status = BLKIF_BE_STATUS_OKAY;
break;
}
@@ -395,7 +420,7 @@
{
blkif_be_disconnect_t *req =
(blkif_be_disconnect_t *)&msg->msg[0];
- vaddr_t ring_addr;
+ int s;
if (msg->length != sizeof(blkif_be_disconnect_t))
goto error;
@@ -406,12 +431,12 @@
}
hypervisor_mask_event(xbdi->evtchn);
event_remove_handler(xbdi->evtchn, xbdback_evthandler, xbdi);
- ring_addr = (vaddr_t)xbdi->blk_ring;
- pmap_remove(pmap_kernel(), ring_addr, ring_addr + PAGE_SIZE);
- uvm_km_free(kernel_map, ring_addr, PAGE_SIZE,
- UVM_KMF_VAONLY);
- req->status = BLKIF_BE_STATUS_OKAY;
- break;
+ xbdi->status = DISCONNECTING;
+ xbdi->disconnect_rspid = msg->id;
+ s = splbio();
+ xbdi_put(xbdi);
+ splx(s);
+ return;
}
case CMSG_BLKIF_BE_VBD_CREATE:
{
@@ -590,6 +615,30 @@
return;
}
+static void xbdback_finish_disconnect(struct xbdback_instance *xbdi)
+{
+ ctrl_msg_t cmsg;
+ blkif_be_disconnect_t *pdisc = (blkif_be_disconnect_t *)&cmsg.msg;
+ vaddr_t ring_addr;
+
+ KASSERT(xbdi->status == DISCONNECTING);
+
+ ring_addr = (vaddr_t)xbdi->blk_ring;
+ pmap_remove(pmap_kernel(), ring_addr, ring_addr + PAGE_SIZE);
+ xbdi->status = DISCONNECTED;
+
+ memset(&cmsg, 0, sizeof(cmsg));
+ cmsg.type = CMSG_BLKIF_BE;
+ cmsg.subtype = CMSG_BLKIF_BE_DISCONNECT;
+ cmsg.id = xbdi->disconnect_rspid;
+ cmsg.length = sizeof(blkif_be_disconnect_t);
+ pdisc->domid = xbdi->domid;
+ pdisc->blkif_handle = xbdi->handle;
+ pdisc->status = BLKIF_BE_STATUS_OKAY;
+
+ ctrl_if_send_response(&cmsg);
+}
+
static struct xbdback_instance *
xbdif_lookup(domid_t dom , uint32_t handle)
{
@@ -618,6 +667,7 @@
xbdback_evthandler(void *arg)
{
struct xbdback_instance *xbdi = arg;
+
if (xbdi->cont == NULL) {
xbdi->cont = xbdback_co_main;
xbdback_trampoline(xbdi, xbdi);
@@ -728,7 +778,7 @@
printf("xbdback_io domain %d: unknown vbd %d\n",
xbdi->domid, xbdi->xen_req->device);
error = EINVAL;
- goto end;
+ goto end;
}
if (xbdi->xen_req->operation == BLKIF_OP_WRITE) {
if (xbdi->req_vbd->flags & VBD_F_RO) {
@@ -854,6 +904,8 @@
vaddr_t start_offset; /* start offset in vm area */
int buf_flags;
+ xbdi_get(xbdi);
+
xbd_io = xbdi->io = obj;
xbd_io->xio_xbdi = xbdi;
SLIST_INIT(&xbd_io->xio_rq);
@@ -1067,6 +1119,7 @@
xbd_req->rq_operation, error);
xbdback_pool_put(&xbdback_request_pool, xbd_req);
}
+ xbdi_put(xbdi);
xbdback_pool_put(&xbdback_io_pool, xbd_io);
}
Home |
Main Index |
Thread Index |
Old Index