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[PATCH] block/export: Fix vhost-user-blk shutdown with requests in fligh
From: |
Kevin Wolf |
Subject: |
[PATCH] block/export: Fix vhost-user-blk shutdown with requests in flight |
Date: |
Tue, 25 Jan 2022 16:14:35 +0100 |
The vhost-user-blk export runs requests asynchronously in their own
coroutine. When the vhost connection goes away and we want to stop the
vhost-user server, we need to wait for these coroutines to stop before
we can unmap the shared memory. Otherwise, they would still access the
unmapped memory and crash.
This introduces a refcount to VuServer which is increased when spawning
a new request coroutine and decreased before the coroutine exits. The
memory is only unmapped when the refcount reaches zero.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
include/qemu/vhost-user-server.h | 5 +++++
block/export/vhost-user-blk-server.c | 5 +++++
util/vhost-user-server.c | 22 ++++++++++++++++++++++
3 files changed, 32 insertions(+)
diff --git a/include/qemu/vhost-user-server.h b/include/qemu/vhost-user-server.h
index 121ea1dedf..cd43193b80 100644
--- a/include/qemu/vhost-user-server.h
+++ b/include/qemu/vhost-user-server.h
@@ -42,6 +42,8 @@ typedef struct {
const VuDevIface *vu_iface;
/* Protected by ctx lock */
+ unsigned int refcount;
+ bool wait_idle;
VuDev vu_dev;
QIOChannel *ioc; /* The I/O channel with the client */
QIOChannelSocket *sioc; /* The underlying data channel with the client */
@@ -59,6 +61,9 @@ bool vhost_user_server_start(VuServer *server,
void vhost_user_server_stop(VuServer *server);
+void vhost_user_server_ref(VuServer *server);
+void vhost_user_server_unref(VuServer *server);
+
void vhost_user_server_attach_aio_context(VuServer *server, AioContext *ctx);
void vhost_user_server_detach_aio_context(VuServer *server);
diff --git a/block/export/vhost-user-blk-server.c
b/block/export/vhost-user-blk-server.c
index 1862563336..a129204c44 100644
--- a/block/export/vhost-user-blk-server.c
+++ b/block/export/vhost-user-blk-server.c
@@ -172,6 +172,7 @@ vu_blk_discard_write_zeroes(VuBlkExport *vexp, struct iovec
*iov,
return VIRTIO_BLK_S_IOERR;
}
+/* Called with server refcount increased, must decrease before returning */
static void coroutine_fn vu_blk_virtio_process_req(void *opaque)
{
VuBlkReq *req = opaque;
@@ -286,10 +287,12 @@ static void coroutine_fn vu_blk_virtio_process_req(void
*opaque)
}
vu_blk_req_complete(req);
+ vhost_user_server_unref(server);
return;
err:
free(req);
+ vhost_user_server_unref(server);
}
static void vu_blk_process_vq(VuDev *vu_dev, int idx)
@@ -310,6 +313,8 @@ static void vu_blk_process_vq(VuDev *vu_dev, int idx)
Coroutine *co =
qemu_coroutine_create(vu_blk_virtio_process_req, req);
+
+ vhost_user_server_ref(server);
qemu_coroutine_enter(co);
}
}
diff --git a/util/vhost-user-server.c b/util/vhost-user-server.c
index f68287e811..f66fbba710 100644
--- a/util/vhost-user-server.c
+++ b/util/vhost-user-server.c
@@ -74,6 +74,20 @@ static void panic_cb(VuDev *vu_dev, const char *buf)
error_report("vu_panic: %s", buf);
}
+void vhost_user_server_ref(VuServer *server)
+{
+ assert(!server->wait_idle);
+ server->refcount++;
+}
+
+void vhost_user_server_unref(VuServer *server)
+{
+ server->refcount--;
+ if (server->wait_idle && !server->refcount) {
+ aio_co_wake(server->co_trip);
+ }
+}
+
static bool coroutine_fn
vu_message_read(VuDev *vu_dev, int conn_fd, VhostUserMsg *vmsg)
{
@@ -177,6 +191,14 @@ static coroutine_fn void vu_client_trip(void *opaque)
/* Keep running */
}
+ if (server->refcount) {
+ /* Wait for requests to complete before we can unmap the memory */
+ server->wait_idle = true;
+ qemu_coroutine_yield();
+ server->wait_idle = false;
+ }
+ assert(server->refcount == 0);
+
vu_deinit(vu_dev);
/* vu_deinit() should have called remove_watch() */
--
2.31.1
- [PATCH] block/export: Fix vhost-user-blk shutdown with requests in flight,
Kevin Wolf <=