qemu-kvm/kvm-scsi-remove-AioContext-locking.patch

From 61d605433a5edfcc7fe836fd399106ed1e1907bb Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Tue, 5 Dec 2023 13:20:05 -0500
Subject: [PATCH 088/101] scsi: remove AioContext locking

RH-Author: Kevin Wolf <kwolf@redhat.com>
RH-MergeRequest: 214: Remove AioContext lock
RH-Jira: RHEL-15965
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Commit: [19/26] 12a8e26670074a17dd2b0cfac06e0aea03b3068f (kmwolf/centos-qemu-kvm)

The AioContext lock no longer has any effect. Remove it.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20231205182011.1976568-9-stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 hw/scsi/scsi-bus.c              |  2 --
 hw/scsi/scsi-disk.c             | 31 +++++--------------------------
 hw/scsi/virtio-scsi.c           | 18 ------------------
 include/hw/virtio/virtio-scsi.h | 14 --------------
 4 files changed, 5 insertions(+), 60 deletions(-)

diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index b649cdf555..5b08cbf60a 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -1732,9 +1732,7 @@ void scsi_device_purge_requests(SCSIDevice *sdev, SCSISense sense)
 {
     scsi_device_for_each_req_async(sdev, scsi_device_purge_one_req, NULL);
 
-    aio_context_acquire(blk_get_aio_context(sdev->conf.blk));
     blk_drain(sdev->conf.blk);
-    aio_context_release(blk_get_aio_context(sdev->conf.blk));
     scsi_device_set_ua(sdev, sense);
 }
 
diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c
index a5048e0aaf..61be3d395a 100644
--- a/hw/scsi/scsi-disk.c
+++ b/hw/scsi/scsi-disk.c
@@ -2339,14 +2339,10 @@ static void scsi_disk_reset(DeviceState *dev)
 {
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev.qdev, dev);
     uint64_t nb_sectors;
-    AioContext *ctx;
 
     scsi_device_purge_requests(&s->qdev, SENSE_CODE(RESET));
 
-    ctx = blk_get_aio_context(s->qdev.conf.blk);
-    aio_context_acquire(ctx);
     blk_get_geometry(s->qdev.conf.blk, &nb_sectors);
-    aio_context_release(ctx);
 
     nb_sectors /= s->qdev.blocksize / BDRV_SECTOR_SIZE;
     if (nb_sectors) {
@@ -2545,15 +2541,13 @@ static void scsi_unrealize(SCSIDevice *dev)
 static void scsi_hd_realize(SCSIDevice *dev, Error **errp)
 {
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
-    AioContext *ctx = NULL;
+
     /* can happen for devices without drive. The error message for missing
      * backend will be issued in scsi_realize
      */
     if (s->qdev.conf.blk) {
-        ctx = blk_get_aio_context(s->qdev.conf.blk);
-        aio_context_acquire(ctx);
         if (!blkconf_blocksizes(&s->qdev.conf, errp)) {
-            goto out;
+            return;
         }
     }
     s->qdev.blocksize = s->qdev.conf.logical_block_size;
@@ -2562,16 +2556,11 @@ static void scsi_hd_realize(SCSIDevice *dev, Error **errp)
         s->product = g_strdup("QEMU HARDDISK");
     }
     scsi_realize(&s->qdev, errp);
-out:
-    if (ctx) {
-        aio_context_release(ctx);
-    }
 }
 
 static void scsi_cd_realize(SCSIDevice *dev, Error **errp)
 {
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
-    AioContext *ctx;
     int ret;
     uint32_t blocksize = 2048;
 
@@ -2587,8 +2576,6 @@ static void scsi_cd_realize(SCSIDevice *dev, Error **errp)
         blocksize = dev->conf.physical_block_size;
     }
 
-    ctx = blk_get_aio_context(dev->conf.blk);
-    aio_context_acquire(ctx);
     s->qdev.blocksize = blocksize;
     s->qdev.type = TYPE_ROM;
     s->features |= 1 << SCSI_DISK_F_REMOVABLE;
@@ -2596,7 +2583,6 @@ static void scsi_cd_realize(SCSIDevice *dev, Error **errp)
         s->product = g_strdup("QEMU CD-ROM");
     }
     scsi_realize(&s->qdev, errp);
-    aio_context_release(ctx);
 }
 
 
@@ -2727,7 +2713,6 @@ static int get_device_type(SCSIDiskState *s)
 static void scsi_block_realize(SCSIDevice *dev, Error **errp)
 {
     SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev, dev);
-    AioContext *ctx;
     int sg_version;
     int rc;
 
@@ -2742,9 +2727,6 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp)
                           "be removed in a future version");
     }
 
-    ctx = blk_get_aio_context(s->qdev.conf.blk);
-    aio_context_acquire(ctx);
-
     /* check we are using a driver managing SG_IO (version 3 and after) */
     rc = blk_ioctl(s->qdev.conf.blk, SG_GET_VERSION_NUM, &sg_version);
     if (rc < 0) {
@@ -2752,18 +2734,18 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp)
         if (rc != -EPERM) {
             error_append_hint(errp, "Is this a SCSI device?\n");
         }
-        goto out;
+        return;
     }
     if (sg_version < 30000) {
         error_setg(errp, "scsi generic interface too old");
-        goto out;
+        return;
     }
 
     /* get device type from INQUIRY data */
     rc = get_device_type(s);
     if (rc < 0) {
         error_setg(errp, "INQUIRY failed");
-        goto out;
+        return;
     }
 
     /* Make a guess for the block size, we'll fix it when the guest sends.
@@ -2783,9 +2765,6 @@ static void scsi_block_realize(SCSIDevice *dev, Error **errp)
 
     scsi_realize(&s->qdev, errp);
     scsi_generic_read_device_inquiry(&s->qdev);
-
-out:
-    aio_context_release(ctx);
 }
 
 typedef struct SCSIBlockReq {
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 4f8d35facc..ca365a70e9 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -642,9 +642,7 @@ static void virtio_scsi_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
         return;
     }
 
-    virtio_scsi_acquire(s);
     virtio_scsi_handle_ctrl_vq(s, vq);
-    virtio_scsi_release(s);
 }
 
 static void virtio_scsi_complete_cmd_req(VirtIOSCSIReq *req)
@@ -882,9 +880,7 @@ static void virtio_scsi_handle_cmd(VirtIODevice *vdev, VirtQueue *vq)
         return;
     }
 
-    virtio_scsi_acquire(s);
     virtio_scsi_handle_cmd_vq(s, vq);
-    virtio_scsi_release(s);
 }
 
 static void virtio_scsi_get_config(VirtIODevice *vdev,
@@ -1031,9 +1027,7 @@ static void virtio_scsi_handle_event(VirtIODevice *vdev, VirtQueue *vq)
         return;
     }
 
-    virtio_scsi_acquire(s);
     virtio_scsi_handle_event_vq(s, vq);
-    virtio_scsi_release(s);
 }
 
 static void virtio_scsi_change(SCSIBus *bus, SCSIDevice *dev, SCSISense sense)
@@ -1052,9 +1046,7 @@ static void virtio_scsi_change(SCSIBus *bus, SCSIDevice *dev, SCSISense sense)
             },
         };
 
-        virtio_scsi_acquire(s);
         virtio_scsi_push_event(s, &info);
-        virtio_scsi_release(s);
     }
 }
 
@@ -1071,17 +1063,13 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     VirtIODevice *vdev = VIRTIO_DEVICE(hotplug_dev);
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
     SCSIDevice *sd = SCSI_DEVICE(dev);
-    AioContext *old_context;
     int ret;
 
     if (s->ctx && !s->dataplane_fenced) {
         if (blk_op_is_blocked(sd->conf.blk, BLOCK_OP_TYPE_DATAPLANE, errp)) {
             return;
         }
-        old_context = blk_get_aio_context(sd->conf.blk);
-        aio_context_acquire(old_context);
         ret = blk_set_aio_context(sd->conf.blk, s->ctx, errp);
-        aio_context_release(old_context);
         if (ret < 0) {
             return;
         }
@@ -1097,10 +1085,8 @@ static void virtio_scsi_hotplug(HotplugHandler *hotplug_dev, DeviceState *dev,
             },
         };
 
-        virtio_scsi_acquire(s);
         virtio_scsi_push_event(s, &info);
         scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
-        virtio_scsi_release(s);
     }
 }
 
@@ -1122,17 +1108,13 @@ static void virtio_scsi_hotunplug(HotplugHandler *hotplug_dev, DeviceState *dev,
     qdev_simple_device_unplug_cb(hotplug_dev, dev, errp);
 
     if (s->ctx) {
-        virtio_scsi_acquire(s);
         /* If other users keep the BlockBackend in the iothread, that's ok */
         blk_set_aio_context(sd->conf.blk, qemu_get_aio_context(), NULL);
-        virtio_scsi_release(s);
     }
 
     if (virtio_vdev_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) {
-        virtio_scsi_acquire(s);
         virtio_scsi_push_event(s, &info);
         scsi_bus_set_ua(&s->bus, SENSE_CODE(REPORTED_LUNS_CHANGED));
-        virtio_scsi_release(s);
     }
 }
 
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index da8cb928d9..7f0573b1bf 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -101,20 +101,6 @@ struct VirtIOSCSI {
     uint32_t host_features;
 };
 
-static inline void virtio_scsi_acquire(VirtIOSCSI *s)
-{
-    if (s->ctx) {
-        aio_context_acquire(s->ctx);
-    }
-}
-
-static inline void virtio_scsi_release(VirtIOSCSI *s)
-{
-    if (s->ctx) {
-        aio_context_release(s->ctx);
-    }
-}
-
 void virtio_scsi_common_realize(DeviceState *dev,
                                 VirtIOHandleOutput ctrl,
                                 VirtIOHandleOutput evt,
-- 
2.39.3