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When disconnecting a device, we have to wait for pending I/O before releasing

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the ressources (this can lead to a dom0 kernel crash when destroying a domain
with active I/O going). For this, add a refcount to struct xbdback_instance,
and defer CMSG_BLKIF_BE_DISCONNECT reply until refcount is back to 0 (which
means all queued buffers have completed).
Based on patch sent by Jed Davis on port-xen.
This commit is contained in:
bouyer 2005-09-20 20:29:18 +00:00
parent 9c9c9cc011
commit 0b1f7e4a8c
1 changed files with 71 additions and 18 deletions
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89
sys/arch/xen/xen/xbdback.c
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@ -1,4 +1,4 @@
/* $NetBSD: xbdback.c,v 1.15 2005/09/10 18:00:49 bouyer Exp $ */
/* $NetBSD: xbdback.c,v 1.16 2005/09/20 20:29:18 bouyer Exp $ */
/*
* Copyright (c) 2005 Manuel Bouyer.
@ -75,7 +75,7 @@ struct xbdback_fragment;
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 @@ struct xbdback_instance {
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 @@ struct xbdback_instance {
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 @@ struct xbdback_instance {
SLIST_HEAD(, xbd_vbd) vbds; /* list of virtual block devices */
};
/* Manipulation of the above reference count. */
/* XXXjld@panix.com: 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 @@ struct timeval xbdback_fragio_intvl = { 60, 0 };
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 @@ xbdback_ctrlif_rx(ctrl_msg_t *msg, unsigned long id)
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 @@ xbdback_ctrlif_rx(ctrl_msg_t *msg, unsigned long id)
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 @@ xbdback_ctrlif_rx(ctrl_msg_t *msg, unsigned long id)
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 @@ xbdback_ctrlif_rx(ctrl_msg_t *msg, unsigned long id)
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 @@ xbdback_ctrlif_rx(ctrl_msg_t *msg, unsigned long id)
{
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 @@ xbdback_ctrlif_rx(ctrl_msg_t *msg, unsigned long id)
}
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 @@ end:
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 @@ static int
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 @@ xbdback_co_io(struct xbdback_instance *xbdi, void *obj)
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 @@ xbdback_co_io_gotio(struct xbdback_instance *xbdi, void *obj)
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 @@ xbdback_iodone(struct buf *bp)
xbd_req->rq_operation, error);
xbdback_pool_put(&xbdback_request_pool, xbd_req);
}
xbdi_put(xbdi);
xbdback_pool_put(&xbdback_io_pool, xbd_io);
}