[PULL,16/33] scsi: assert that callbacks run in the correct AioContext

Commit Message

Kevin Wolf Dec. 21, 2023, 9:23 p.m. UTC

From: Stefan Hajnoczi <[e-mail]>

Since the removal of AioContext locking, the correctness of the code
relies on running requests from a single AioContext at any given time.

Add assertions that verify that callbacks are invoked in the correct
AioContext.

Signed-off-by: Stefan Hajnoczi <[e-mail]>
Message-ID: <[e-mail]>
Reviewed-by: Kevin Wolf <[e-mail]>
Signed-off-by: Kevin Wolf <[e-mail]>
---
 hw/scsi/scsi-disk.c  | 14 ++++++++++++++
 system/dma-helpers.c |  3 +++
 2 files changed, 17 insertions(+)

Patch

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index 2c1bbb3530..a5048e0aaf 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -273,6 +273,10 @@  static void scsi_aio_complete(void *opaque, int ret)
     SCSIDiskReq *r = (SCSIDiskReq *)opaque;
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
 
+    /* The request must only run in the BlockBackend's AioContext */
+    assert(blk_get_aio_context(s->qdev.conf.blk) ==
+           qemu_get_current_aio_context());
+
     assert(r->req.aiocb != NULL);
     r->req.aiocb = NULL;
 
@@ -370,8 +374,13 @@  static void scsi_dma_complete(void *opaque, int ret)
 
 static void scsi_read_complete_noio(SCSIDiskReq *r, int ret)
 {
+    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
     uint32_t n;
 
+    /* The request must only run in the BlockBackend's AioContext */
+    assert(blk_get_aio_context(s->qdev.conf.blk) ==
+           qemu_get_current_aio_context());
+
     assert(r->req.aiocb == NULL);
     if (scsi_disk_req_check_error(r, ret, false)) {
         goto done;
@@ -496,8 +505,13 @@  static void scsi_read_data(SCSIRequest *req)
 
 static void scsi_write_complete_noio(SCSIDiskReq *r, int ret)
 {
+    SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);
     uint32_t n;
 
+    /* The request must only run in the BlockBackend's AioContext */
+    assert(blk_get_aio_context(s->qdev.conf.blk) ==
+           qemu_get_current_aio_context());
+
     assert (r->req.aiocb == NULL);
     if (scsi_disk_req_check_error(r, ret, false)) {
         goto done;
diff --git a/system/dma-helpers.c b/system/dma-helpers.c
index 528117f256..9b221cf94e 100644
--- a/system/dma-helpers.c
+++ b/system/dma-helpers.c
@@ -119,6 +119,9 @@  static void dma_blk_cb(void *opaque, int ret)
 
     trace_dma_blk_cb(dbs, ret);
 
+    /* DMAAIOCB is not thread-safe and must be accessed only from dbs->ctx */
+    assert(ctx == qemu_get_current_aio_context());
+
     dbs->acb = NULL;
     dbs->offset += dbs->iov.size;