[v1] Miscellaneous changes for 2025-10-28

[PULL 13/18] scsi: make SCSIRequest refcount atomic

Paolo Bonzini posted 18 patches 2 weeks, 3 days ago

Diff against v2
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Maintainers: Magnus Kulke <magnus.kulke@linux.microsoft.com>, Wei Liu <wei.liu@kernel.org>, "Gonglei (Arei)" <arei.gonglei@huawei.com>, Zhenwei Pi <pizhenwei@bytedance.com>, "Michael S. Tsirkin" <mst@redhat.com>, Stefano Garzarella <sgarzare@redhat.com>, Laurent Vivier <lvivier@redhat.com>, Amit Shah <amit@kernel.org>, Stefan Berger <stefanb@linux.vnet.ibm.com>, "Marc-André Lureau" <marcandre.lureau@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, "Alex Bennée" <alex.bennee@linaro.org>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Peter Maydell <peter.maydell@linaro.org>, Igor Mitsyanko <i.mitsyanko@gmail.com>, "Clément Chigot" <chigot@adacore.com>, Frederic Konrad <konrad.frederic@yahoo.fr>, Alberto Garcia <berto@igalia.com>, Thomas Huth <huth@tuxfamily.org>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, Jason Herne <jjherne@linux.ibm.com>, Yoshinori Sato <yoshinori.sato@nifty.com>, Magnus Damm <magnus.damm@gmail.com>, Nicholas Piggin <npiggin@gmail.com>, Harsh Prateek Bora <harshpb@linux.ibm.com>, "Collin L. Walling" <walling@linux.ibm.com>, Stefano Stabellini <sstabellini@kernel.org>, Anthony PERARD <anthony@xenproject.org>, Paul Durrant <paul@xen.org>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Alistair Francis <alistair@alistair23.me>, "Daniel P. Berrangé" <berrange@redhat.com>, Eduardo Habkost <eduardo@habkost.net>, Richard Henderson <richard.henderson@linaro.org>, Helge Deller <deller@gmx.de>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Corey Minyard <minyard@acm.org>, Paul Burton <paulburton@kernel.org>, Aleksandar Rikalo <arikalo@gmail.com>, Aurelien Jarno <aurelien@aurel32.net>, Palmer Dabbelt <palmer@dabbelt.com>, Weiwei Li <liwei1518@gmail.com>, Daniel Henrique Barboza <dbarboza@ventanamicro.com>, Liu Zhiwei <zhiwei_liu@linux.alibaba.com>, Fam Zheng <fam@euphon.net>, Samuel Thibault <samuel.thibault@ens-lyon.org>, Michael Rolnik <mrolnik@gmail.com>, Antony Pavlov <antonynpavlov@gmail.com>, Joel Stanley <joel@jms.id.au>, Vijai Kumar K <vijai@behindbytes.com>, Samuel Tardieu <sam@rfc1149.net>, Gustavo Romero <gustavo.romero@linaro.org>, Raphael Norwitz <raphael@enfabrica.net>, Stefan Hajnoczi <stefanha@redhat.com>, Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>, Dmitry Osipenko <dmitry.osipenko@collabora.com>, Markus Armbruster <armbru@redhat.com>, Fabiano Rosas <farosas@suse.de>, "Dr. David Alan Gilbert" <dave@treblig.org>, Zhang Chen <zhangckid@gmail.com>, Li Zhijian <lizhijian@fujitsu.com>, Jason Wang <jasowang@redhat.com>, Manos Pitsidianakis <manos.pitsidianakis@linaro.org>, John Snow <jsnow@redhat.com>, Cleber Rosa <crosa@redhat.com>, Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Phil Dennis-Jordan <phil@philjordan.eu>, Marcelo Tosatti <mtosatti@redhat.com>, Reinoud Zandijk <reinoud@netbsd.org>, Sunil Muthuswamy <sunilmut@microsoft.com>, Max Filippov <jcmvbkbc@gmail.com>, Lukas Straub <lukasstraub2@web.de>

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[PULL 13/18] scsi: make SCSIRequest refcount atomic

Posted by Paolo Bonzini 2 weeks, 3 days ago

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/scsi/scsi-bus.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/hw/scsi/scsi-bus.c b/hw/scsi/scsi-bus.c
index 9b12ee7f1c6..b9b115deedd 100644
--- a/hw/scsi/scsi-bus.c
+++ b/hw/scsi/scsi-bus.c
@@ -823,7 +823,6 @@ SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d,
 {
     SCSIRequest *req;
     SCSIBus *bus = scsi_bus_from_device(d);
-    BusState *qbus = BUS(bus);
     const int memset_off = offsetof(SCSIRequest, sense)
                            + sizeof(req->sense);
 
@@ -838,8 +837,6 @@ SCSIRequest *scsi_req_alloc(const SCSIReqOps *reqops, SCSIDevice *d,
     req->status = -1;
     req->host_status = -1;
     req->ops = reqops;
-    object_ref(OBJECT(d));
-    object_ref(OBJECT(qbus->parent));
     notifier_list_init(&req->cancel_notifiers);
 
     if (reqops->init_req) {
@@ -1496,15 +1493,15 @@ void scsi_device_report_change(SCSIDevice *dev, SCSISense sense)
 
 SCSIRequest *scsi_req_ref(SCSIRequest *req)
 {
-    assert(req->refcount > 0);
-    req->refcount++;
+    assert(qatomic_read(&req->refcount) > 0);
+    qatomic_inc(&req->refcount);
     return req;
 }
 
 void scsi_req_unref(SCSIRequest *req)
 {
-    assert(req->refcount > 0);
-    if (--req->refcount == 0) {
+    assert(qatomic_read(&req->refcount) > 0);
+    if (qatomic_fetch_dec(&req->refcount) == 1) {
         BusState *qbus = req->dev->qdev.parent_bus;
         SCSIBus *bus = DO_UPCAST(SCSIBus, qbus, qbus);
 
@@ -1514,8 +1511,6 @@ void scsi_req_unref(SCSIRequest *req)
         if (req->ops->free_req) {
             req->ops->free_req(req);
         }
-        object_unref(OBJECT(req->dev));
-        object_unref(OBJECT(qbus->parent));
         g_free(req);
     }
 }
-- 
2.51.1