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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36079d78ce2sm10403350f8f.19.2024.06.17.04.31.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 Jun 2024 04:31:29 -0700 (PDT) Message-ID: Date: Mon, 17 Jun 2024 13:31:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 01/17] vfio: Make vfio_devices_dma_logging_start() return bool Content-Language: en-US To: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , qemu-devel@nongnu.org Cc: Zhenzhong Duan , Alex Williamson References: <20240617063409.34393-1-clg@redhat.com> <20240617063409.34393-2-clg@redhat.com> From: Eric Auger In-Reply-To: <20240617063409.34393-2-clg@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.148, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Reply-To: eric.auger@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Hi Cédric, On 6/17/24 08:33, Cédric Le Goater wrote: > Since vfio_devices_dma_logging_start() takes an 'Error **' argument, > best practices suggest to return a bool. See the api/error.h Rules > section. It will simplify potential changes coming after. As I already mentionned the Rules section does not say that, as far as I understand: It is allowed to either return a bool, a pointer-value, an integer, along with an error handle: "  *   • bool-valued functions return true on success / false on failure,  *   • pointer-valued functions return non-null / null pointer, and  *   • integer-valued functions return non-negative / negative. " Personally I don't like much returning a bool as I think it rather complexifies the code and to me that kind of change is error prone. > > vfio_container_set_dirty_page_tracking() could be modified in the same > way but the errno value can be saved in the migration stream when > called from vfio_listener_log_global_stop(). > Signed-off-by: Cédric Le Goater > Reviewed-by: Zhenzhong Duan > --- > hw/vfio/common.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/hw/vfio/common.c b/hw/vfio/common.c > index 9e4c0cc95ff90209d3e8184035af0806a2bf890b..d48cd9b9361a92d184e423ffc60aabaff40fb487 100644 > --- a/hw/vfio/common.c > +++ b/hw/vfio/common.c > @@ -1020,7 +1020,7 @@ static void vfio_device_feature_dma_logging_start_destroy( > g_free(feature); > } > > -static int vfio_devices_dma_logging_start(VFIOContainerBase *bcontainer, > +static bool vfio_devices_dma_logging_start(VFIOContainerBase *bcontainer, > Error **errp) > { > struct vfio_device_feature *feature; > @@ -1033,7 +1033,7 @@ static int vfio_devices_dma_logging_start(VFIOContainerBase *bcontainer, > &ranges); > if (!feature) { > error_setg_errno(errp, errno, "Failed to prepare DMA logging"); > - return -errno; > + return false; > } > > QLIST_FOREACH(vbasedev, &bcontainer->device_list, container_next) { > @@ -1058,7 +1058,7 @@ out: > > vfio_device_feature_dma_logging_start_destroy(feature); > > - return ret; > + return ret == 0; > } > > static bool vfio_listener_log_global_start(MemoryListener *listener, > @@ -1067,18 +1067,18 @@ static bool vfio_listener_log_global_start(MemoryListener *listener, > ERRP_GUARD(); > VFIOContainerBase *bcontainer = container_of(listener, VFIOContainerBase, > listener); > - int ret; > + bool ret; > > if (vfio_devices_all_device_dirty_tracking(bcontainer)) { > ret = vfio_devices_dma_logging_start(bcontainer, errp); > } else { > - ret = vfio_container_set_dirty_page_tracking(bcontainer, true, errp); > + ret = vfio_container_set_dirty_page_tracking(bcontainer, true, errp) == 0; why vfio_container_set_dirty_page_tracking(bcontainer, true, errp) doesn't return a bool then? Eric > } > > - if (ret) { > + if (!ret) { > error_prepend(errp, "vfio: Could not start dirty page tracking - "); > } > - return !ret; > + return ret; > } > > static void vfio_listener_log_global_stop(MemoryListener *listener)