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([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id ae14-20020a17090725ce00b00947a939f6e0sm5693767ejc.77.2023.04.04.06.46.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Apr 2023 06:46:35 -0700 (PDT) Message-ID: <92b731c7-81d4-ef54-cca9-9dcb944e94f0@redhat.com> Date: Tue, 4 Apr 2023 15:46:34 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH 11/13] block/fuse: take AioContext lock around blk_exp_ref/unref() Content-Language: en-US To: Stefan Hajnoczi , qemu-devel@nongnu.org Cc: Julia Suvorova , Kevin Wolf , Peter Lieven , Coiby Xu , xen-devel@lists.xenproject.org, Richard Henderson , Stefano Garzarella , qemu-block@nongnu.org, Eduardo Habkost , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Paul Durrant , "Richard W.M. Jones" , "Dr. David Alan Gilbert" , Marcel Apfelbaum , Aarushi Mehta , Stefano Stabellini , Fam Zheng , David Woodhouse , Stefan Weil , Juan Quintela , Xie Yongji , Hanna Reitz , Ronnie Sahlberg , eesposit@redhat.com, "Michael S. Tsirkin" , =?UTF-8?Q?Daniel_P=2e_Berrang=c3=a9?= , Anthony Perard References: <20230403183004.347205-1-stefanha@redhat.com> <20230403183004.347205-12-stefanha@redhat.com> From: Paolo Bonzini In-Reply-To: <20230403183004.347205-12-stefanha@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -39 X-Spam_score: -4.0 X-Spam_bar: ---- X-Spam_report: (-4.0 / 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, NICE_REPLY_A=-1.925, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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 4/3/23 20:30, Stefan Hajnoczi wrote: > These functions must be called with the AioContext acquired: > > /* Callers must hold exp->ctx lock */ > void blk_exp_ref(BlockExport *exp) > ... > /* Callers must hold exp->ctx lock */ > void blk_exp_unref(BlockExport *exp) > > Signed-off-by: Stefan Hajnoczi > --- > block/export/fuse.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/block/export/fuse.c b/block/export/fuse.c > index 06fa41079e..18394f9e07 100644 > --- a/block/export/fuse.c > +++ b/block/export/fuse.c > @@ -244,7 +244,9 @@ static void read_from_fuse_export(void *opaque) > FuseExport *exp = opaque; > int ret; > > + aio_context_acquire(exp->common.ctx); > blk_exp_ref(&exp->common); > + aio_context_release(exp->common.ctx); > > do { > ret = fuse_session_receive_buf(exp->fuse_session, &exp->fuse_buf); > @@ -256,7 +258,9 @@ static void read_from_fuse_export(void *opaque) > fuse_session_process_buf(exp->fuse_session, &exp->fuse_buf); > > out: > + aio_context_acquire(exp->common.ctx); > blk_exp_unref(&exp->common); > + aio_context_release(exp->common.ctx); > } Since the actual thread-unsafe work is done in a bottom half, perhaps instead you can use qatomic_inc and qatomic_fetch_dec in blk_exp_{ref,unref}? Paolo