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[99.254.114.190]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-3a808e1eb4bsm5090565ab.49.2024.12.05.08.17.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Dec 2024 08:17:24 -0800 (PST) Date: Thu, 5 Dec 2024 11:17:22 -0500 From: Peter Xu To: "Maciej S. Szmigiero" Cc: Fabiano Rosas , Alex Williamson , =?utf-8?Q?C=C3=A9dric?= Le Goater , Eric Blake , Markus Armbruster , Daniel P =?utf-8?B?LiBCZXJyYW5nw6k=?= , Avihai Horon , Joao Martins , qemu-devel@nongnu.org Subject: Re: [PATCH v3 11/24] migration/multifd: Make multifd_send() thread safe Message-ID: References: <20fadbcc46cc7cc698ce24e83a3e0fc0c35cd2d8.1731773021.git.maciej.szmigiero@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20fadbcc46cc7cc698ce24e83a3e0fc0c35cd2d8.1731773021.git.maciej.szmigiero@oracle.com> 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: -50 X-Spam_score: -5.1 X-Spam_bar: ----- X-Spam_report: (-5.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.996, 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_H2=-0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=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 Sun, Nov 17, 2024 at 08:20:06PM +0100, Maciej S. Szmigiero wrote: > From: "Maciej S. Szmigiero" > > multifd_send() function is currently not thread safe, make it thread safe > by holding a lock during its execution. > > This way it will be possible to safely call it concurrently from multiple > threads. > > Signed-off-by: Maciej S. Szmigiero Reviewed-by: Peter Xu One nitpick: > --- > migration/multifd.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/migration/multifd.c b/migration/multifd.c > index 9578a985449b..4575495c8816 100644 > --- a/migration/multifd.c > +++ b/migration/multifd.c > @@ -50,6 +50,10 @@ typedef struct { > > struct { > MultiFDSendParams *params; > + > + /* multifd_send() body is not thread safe, needs serialization */ > + QemuMutex multifd_send_mutex; > + > /* > * Global number of generated multifd packets. > * > @@ -331,6 +335,7 @@ static void multifd_send_kick_main(MultiFDSendParams *p) > */ > bool multifd_send(MultiFDSendData **send_data) > { > + QEMU_LOCK_GUARD(&multifd_send_state->multifd_send_mutex); Better move this after the varaible declarations to be clear.. Perhaps even after multifd_send_should_exit() because reading that doesn't need a lock, just in case something wanna quit but keep stuck with the mutex. > int i; > static int next_channel; > MultiFDSendParams *p = NULL; /* make happy gcc */ > @@ -508,6 +513,7 @@ static void multifd_send_cleanup_state(void) > socket_cleanup_outgoing_migration(); > qemu_sem_destroy(&multifd_send_state->channels_created); > qemu_sem_destroy(&multifd_send_state->channels_ready); > + qemu_mutex_destroy(&multifd_send_state->multifd_send_mutex); > g_free(multifd_send_state->params); > multifd_send_state->params = NULL; > g_free(multifd_send_state); > @@ -853,6 +859,7 @@ 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); > + qemu_mutex_init(&multifd_send_state->multifd_send_mutex); > 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); > -- Peter Xu