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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7a198fbfec8sm386084085a.54.2024.07.22.12.20.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Jul 2024 12:20:43 -0700 (PDT) Date: Mon, 22 Jul 2024 15:20:41 -0400 From: Peter Xu To: Fabiano Rosas Cc: qemu-devel@nongnu.org, "Maciej S . Szmigiero" Subject: Re: [RFC PATCH v2 4/9] migration/multifd: Make MultiFDPages_t:offset a flexible array member Message-ID: References: <20240722175914.24022-1-farosas@suse.de> <20240722175914.24022-5-farosas@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240722175914.24022-5-farosas@suse.de> Received-SPF: pass client-ip=170.10.129.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.133, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, 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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Jul 22, 2024 at 02:59:09PM -0300, Fabiano Rosas wrote: > We're about to use MultiFDPages_t from inside the MultiFDSendData > payload union, which means we cannot have pointers to allocated data > inside the pages structure, otherwise we'd lose the reference to that > memory once another payload type touches the union. Move the offset > array into the end of the structure and turn it into a flexible array > member, so it is allocated along with the rest of MultiFDSendData in > the next patches. > > Note that the ramblock pointer is still fine because the storage for > it is not owned by the migration code. > > Signed-off-by: Fabiano Rosas > --- > migration/multifd.c | 21 ++++++--------------- > migration/multifd.h | 4 ++-- > 2 files changed, 8 insertions(+), 17 deletions(-) > > diff --git a/migration/multifd.c b/migration/multifd.c > index 20a767157e..440319b361 100644 > --- a/migration/multifd.c > +++ b/migration/multifd.c > @@ -389,22 +389,10 @@ static int multifd_recv_initial_packet(QIOChannel *c, Error **errp) > return msg.id; > } > > -static MultiFDPages_t *multifd_pages_init(uint32_t n) > -{ > - MultiFDPages_t *pages = g_new0(MultiFDPages_t, 1); > - > - pages->allocated = n; > - pages->offset = g_new0(ram_addr_t, n); > - > - return pages; > -} Considering this is the tricky object to allocate here, shall we keep the function just for readability (and already dedups below two callers)? With it, someone else will notice g_new0() stops working for MultiFDPages_t. Some verbose comment would be nice too. Maybe we can also move multifd_ram_payload_size() from the next patch to here. > - > static void multifd_pages_clear(MultiFDPages_t *pages) > { > multifd_pages_reset(pages); > pages->allocated = 0; > - g_free(pages->offset); > - pages->offset = NULL; > g_free(pages); > } > > @@ -1169,7 +1157,9 @@ bool multifd_send_setup(void) > thread_count = migrate_multifd_channels(); > multifd_send_state = g_malloc0(sizeof(*multifd_send_state)); > multifd_send_state->params = g_new0(MultiFDSendParams, thread_count); > - multifd_send_state->pages = multifd_pages_init(page_count); > + multifd_send_state->pages = g_malloc0(sizeof(MultiFDPages_t) + > + page_count * sizeof(ram_addr_t)); > + multifd_send_state->pages->allocated = page_count; > qemu_sem_init(&multifd_send_state->channels_created, 0); > qemu_sem_init(&multifd_send_state->channels_ready, 0); > qatomic_set(&multifd_send_state->exiting, 0); > @@ -1181,8 +1171,9 @@ bool multifd_send_setup(void) > qemu_sem_init(&p->sem, 0); > qemu_sem_init(&p->sem_sync, 0); > p->id = i; > - p->pages = multifd_pages_init(page_count); > - > + p->pages = g_malloc0(sizeof(MultiFDPages_t) + > + page_count * sizeof(ram_addr_t)); > + p->pages->allocated = page_count; > if (use_packets) { > p->packet_len = sizeof(MultiFDPacket_t) > + sizeof(uint64_t) * page_count; > diff --git a/migration/multifd.h b/migration/multifd.h > index c7b1ebe099..12d4247e23 100644 > --- a/migration/multifd.h > +++ b/migration/multifd.h > @@ -78,9 +78,9 @@ typedef struct { > uint32_t normal_num; > /* number of allocated pages */ > uint32_t allocated; > + RAMBlock *block; > /* offset of each page */ > - ram_addr_t *offset; > - RAMBlock *block; > + ram_addr_t offset[]; > } MultiFDPages_t; > > struct MultiFDRecvData { > -- > 2.35.3 > -- Peter Xu