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| author | Stefan Hajnoczi <stefanha@redhat.com> | 2023-05-16 15:02:36 -0400 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2023-05-30 17:32:02 +0200 |
| commit | 766aa2de0f29b657148e04599320d771c36fd126 (patch) | |
| tree | 911117223771a1574c5a17b938f9beb840aac943 /include/hw | |
| parent | 1665d9326fd2dd97f1f4061decd67702956ec53c (diff) | |
| download | qemu-766aa2de0f29b657148e04599320d771c36fd126.zip qemu-766aa2de0f29b657148e04599320d771c36fd126.tar.gz qemu-766aa2de0f29b657148e04599320d771c36fd126.tar.bz2 | |
virtio-scsi: implement BlockDevOps->drained_begin()
The virtio-scsi Host Bus Adapter provides access to devices on a SCSI
bus. Those SCSI devices typically have a BlockBackend. When the
BlockBackend enters a drained section, the SCSI device must temporarily
stop submitting new I/O requests.
Implement this behavior by temporarily stopping virtio-scsi virtqueue
processing when one of the SCSI devices enters a drained section. The
new scsi_device_drained_begin() API allows scsi-disk to message the
virtio-scsi HBA.
scsi_device_drained_begin() uses a drain counter so that multiple SCSI
devices can have overlapping drained sections. The HBA only sees one
pair of .drained_begin/end() calls.
After this commit, virtio-scsi no longer depends on hw/virtio's
ioeventfd aio_set_event_notifier(is_external=true). This commit is a
step towards removing the aio_disable_external() API.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20230516190238.8401-19-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'include/hw')
| -rw-r--r-- | include/hw/scsi/scsi.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/hw/scsi/scsi.h b/include/hw/scsi/scsi.h index 6f23a7a..e2bb1a2 100644 --- a/include/hw/scsi/scsi.h +++ b/include/hw/scsi/scsi.h @@ -133,6 +133,16 @@ struct SCSIBusInfo { void (*save_request)(QEMUFile *f, SCSIRequest *req); void *(*load_request)(QEMUFile *f, SCSIRequest *req); void (*free_request)(SCSIBus *bus, void *priv); + + /* + * Temporarily stop submitting new requests between drained_begin() and + * drained_end(). Called from the main loop thread with the BQL held. + * + * Implement these callbacks if request processing is triggered by a file + * descriptor like an EventNotifier. Otherwise set them to NULL. + */ + void (*drained_begin)(SCSIBus *bus); + void (*drained_end)(SCSIBus *bus); }; #define TYPE_SCSI_BUS "SCSI" @@ -144,6 +154,8 @@ struct SCSIBus { SCSISense unit_attention; const SCSIBusInfo *info; + + int drain_count; /* protected by BQL */ }; /** @@ -213,6 +225,8 @@ void scsi_req_cancel_complete(SCSIRequest *req); void scsi_req_cancel(SCSIRequest *req); void scsi_req_cancel_async(SCSIRequest *req, Notifier *notifier); void scsi_req_retry(SCSIRequest *req); +void scsi_device_drained_begin(SCSIDevice *sdev); +void scsi_device_drained_end(SCSIDevice *sdev); void scsi_device_purge_requests(SCSIDevice *sdev, SCSISense sense); void scsi_device_set_ua(SCSIDevice *sdev, SCSISense sense); void scsi_device_report_change(SCSIDevice *dev, SCSISense sense); |