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Tsirkin" , Jason Wang Subject: [PATCH v2] hw/virtio/vdpa-dev: Check returned value instead of dereferencing @errp Date: Wed, 17 Jul 2024 00:26:15 +0800 Message-Id: <20240716162615.271010-1-zhao1.liu@intel.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=198.175.65.14; envelope-from=zhao1.liu@intel.com; helo=mgamail.intel.com X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @intel.com) X-ZM-MESSAGEID: 1721146281263116300 As the comment in qapi/error, dereferencing @errp requires ERRP_GUARD(): * =3D Why, when and how to use ERRP_GUARD() =3D * * Without ERRP_GUARD(), use of the @errp parameter is restricted: * - It must not be dereferenced, because it may be null. ... * ERRP_GUARD() lifts these restrictions. * * To use ERRP_GUARD(), add it right at the beginning of the function. * @errp can then be used without worrying about the argument being * NULL or &error_fatal. * * Using it when it's not needed is safe, but please avoid cluttering * the source with useless code. Though vhost_vdpa_device_realize() is called at DeviceClass.realize() context and won't get NULL @errp, it's still better to follow the requirement to add the ERRP_GUARD(). But qemu_open() and vhost_vdpa_device_get_u32()'s return values can distinguish between successful and unsuccessful calls, so check the return values directly without dereferencing @errp, which eliminates the need of ERRP_GUARD(). Cc: "Michael S. Tsirkin" Cc: Jason Wang Acked-by: Eugenio P=C3=A9rez Signed-off-by: Zhao Liu --- v2: * Added a/b from Eugenio. * Deleted unnecessary ERRP_GUARD(). (Eugenio) --- hw/virtio/vdpa-dev.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/hw/virtio/vdpa-dev.c b/hw/virtio/vdpa-dev.c index 64b96b226c39..8a1e16fce3de 100644 --- a/hw/virtio/vdpa-dev.c +++ b/hw/virtio/vdpa-dev.c @@ -63,19 +63,19 @@ static void vhost_vdpa_device_realize(DeviceState *dev,= Error **errp) } =20 v->vhostfd =3D qemu_open(v->vhostdev, O_RDWR, errp); - if (*errp) { + if (v->vhostfd < 0) { return; } =20 v->vdev_id =3D vhost_vdpa_device_get_u32(v->vhostfd, VHOST_VDPA_GET_DEVICE_ID, errp); - if (*errp) { + if (v->vdev_id < 0) { goto out; } =20 max_queue_size =3D vhost_vdpa_device_get_u32(v->vhostfd, VHOST_VDPA_GET_VRING_NUM, e= rrp); - if (*errp) { + if (max_queue_size < 0) { goto out; } =20 @@ -89,7 +89,7 @@ static void vhost_vdpa_device_realize(DeviceState *dev, E= rror **errp) =20 v->num_queues =3D vhost_vdpa_device_get_u32(v->vhostfd, VHOST_VDPA_GET_VQS_COUNT, er= rp); - if (*errp) { + if (v->num_queues < 0) { goto out; } =20 @@ -127,7 +127,7 @@ static void vhost_vdpa_device_realize(DeviceState *dev,= Error **errp) v->config_size =3D vhost_vdpa_device_get_u32(v->vhostfd, VHOST_VDPA_GET_CONFIG_SIZE, errp); - if (*errp) { + if (v->config_size < 0) { goto vhost_cleanup; } =20 --=20 2.34.1