From df836ee4b4e2a69cca5042a3a9daf2c41dc2aa58 Mon Sep 17 00:00:00 2001

From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Tue, 21 Feb 2023 16:22:16 -0500

Subject: [PATCH 11/13] scsi: protect req->aiocb with AioContext lock

RH-Author: Stefan Hajnoczi <stefanha@redhat.com>

RH-MergeRequest: 264: scsi: protect req->aiocb with AioContext lock

RH-Bugzilla: 2090990

RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

RH-Commit: [1/3] e6a6d4109713e0fd6d6c515535c66196fea98688

If requests are being processed in the IOThread when a SCSIDevice is

unplugged, scsi_device_purge_requests() -> scsi_req_cancel_async() races

with I/O completion callbacks. Both threads load and store req->aiocb.

This can lead to assert(r->req.aiocb == NULL) failures and undefined

behavior.

Protect r->req.aiocb with the AioContext lock to prevent the race.

Reviewed-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Message-Id: <20230221212218.1378734-2-stefanha@redhat.com>

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

(cherry picked from commit 7b7fc3d0102dafe8eb44802493036a526e921a71)

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

---

 hw/scsi/scsi-disk.c    | 23 ++++++++++++++++-------

 hw/scsi/scsi-generic.c | 11 ++++++-----

 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c

index d4914178ea..179ce22c4a 100644

--- a/hw/scsi/scsi-disk.c

+++ b/hw/scsi/scsi-disk.c

@@ -270,9 +270,11 @@ static void scsi_aio_complete(void *opaque, int ret)

     SCSIDiskReq *r = (SCSIDiskReq *)opaque;

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

+    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     if (scsi_disk_req_check_error(r, ret, true)) {

         goto done;

     }

@@ -354,10 +356,11 @@ static void scsi_dma_complete(void *opaque, int ret)

     SCSIDiskReq *r = (SCSIDiskReq *)opaque;

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

+    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

     if (ret < 0) {

         block_acct_failed(blk_get_stats(s->qdev.conf.blk), &r->acct);

     } else {

@@ -390,10 +393,11 @@ static void scsi_read_complete(void *opaque, int ret)

     SCSIDiskReq *r = (SCSIDiskReq *)opaque;

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

+    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

     if (ret < 0) {

         block_acct_failed(blk_get_stats(s->qdev.conf.blk), &r->acct);

     } else {

@@ -443,10 +447,11 @@ static void scsi_do_read_cb(void *opaque, int ret)

     SCSIDiskReq *r = (SCSIDiskReq *)opaque;

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

+    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     assert (r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

     if (ret < 0) {

         block_acct_failed(blk_get_stats(s->qdev.conf.blk), &r->acct);

     } else {

@@ -527,10 +532,11 @@ static void scsi_write_complete(void * opaque, int ret)

     SCSIDiskReq *r = (SCSIDiskReq *)opaque;

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

+    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     assert (r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

     if (ret < 0) {

         block_acct_failed(blk_get_stats(s->qdev.conf.blk), &r->acct);

     } else {

@@ -1659,10 +1665,11 @@ static void scsi_unmap_complete(void *opaque, int ret)

     SCSIDiskReq *r = data->r;

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

+    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

     if (scsi_disk_req_check_error(r, ret, true)) {

         scsi_req_unref(&r->req);

         g_free(data);

@@ -1738,9 +1745,11 @@ static void scsi_write_same_complete(void *opaque, int ret)

     SCSIDiskReq *r = data->r;

     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, r->req.dev);

+    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->qdev.conf.blk));

+

     if (scsi_disk_req_check_error(r, ret, true)) {

         goto done;

     }

diff --git a/hw/scsi/scsi-generic.c b/hw/scsi/scsi-generic.c

index 3742899839..a1a40df64b 100644

--- a/hw/scsi/scsi-generic.c

+++ b/hw/scsi/scsi-generic.c

@@ -111,10 +111,11 @@ static void scsi_command_complete(void *opaque, int ret)

     SCSIGenericReq *r = (SCSIGenericReq *)opaque;

     SCSIDevice *s = r->req.dev;

+    aio_context_acquire(blk_get_aio_context(s->conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->conf.blk));

     scsi_command_complete_noio(r, ret);

     aio_context_release(blk_get_aio_context(s->conf.blk));

 }

@@ -269,11 +270,11 @@ static void scsi_read_complete(void * opaque, int ret)

     SCSIDevice *s = r->req.dev;

     int len;

+    aio_context_acquire(blk_get_aio_context(s->conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->conf.blk));

-

     if (ret || r->req.io_canceled) {

         scsi_command_complete_noio(r, ret);

         goto done;

@@ -387,11 +388,11 @@ static void scsi_write_complete(void * opaque, int ret)

     trace_scsi_generic_write_complete(ret);

+    aio_context_acquire(blk_get_aio_context(s->conf.blk));

+

     assert(r->req.aiocb != NULL);

     r->req.aiocb = NULL;

-    aio_context_acquire(blk_get_aio_context(s->conf.blk));

-

     if (ret || r->req.io_canceled) {

         scsi_command_complete_noio(r, ret);

         goto done;

-- 

2.37.3