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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id df15sm10260643edb.24.2021.02.15.07.08.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 15 Feb 2021 07:08:39 -0800 (PST) Subject: Re: [PATCH] monitor: Fix order in monitor_cleanup() To: Kevin Wolf , qemu-devel@nongnu.org References: <20201013125027.41003-1-kwolf@redhat.com> From: Paolo Bonzini Message-ID: <12ad27f6-99f7-5c0f-c24a-f6784da67683@redhat.com> Date: Mon, 15 Feb 2021 16:08:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20201013125027.41003-1-kwolf@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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=-0.001, RCVD_IN_DNSWL_LOW=-0.7, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alex.bennee@linaro.org, armbru@redhat.com, f4bug@amsat.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 13/10/20 14:50, Kevin Wolf wrote: > We can only destroy Monitor objects after we're sure that they are not > in use by the dispatcher coroutine any more. This fixes crashes like the > following where we tried to destroy a monitor mutex while the dispatcher > coroutine still holds it: > > (gdb) bt > #0 0x00007fe541cf4bc5 in raise () at /lib64/libc.so.6 > #1 0x00007fe541cdd8a4 in abort () at /lib64/libc.so.6 > #2 0x000055c24e965327 in error_exit (err=16, msg=0x55c24eead3a0 <__func__.33> "qemu_mutex_destroy") at ../util/qemu-thread-posix.c:37 > #3 0x000055c24e9654c3 in qemu_mutex_destroy (mutex=0x55c25133e0f0) at ../util/qemu-thread-posix.c:70 > #4 0x000055c24e7cfaf1 in monitor_data_destroy_qmp (mon=0x55c25133dfd0) at ../monitor/qmp.c:439 > #5 0x000055c24e7d23bc in monitor_data_destroy (mon=0x55c25133dfd0) at ../monitor/monitor.c:615 > #6 0x000055c24e7d253a in monitor_cleanup () at ../monitor/monitor.c:644 > #7 0x000055c24e6cb002 in qemu_cleanup () at ../softmmu/vl.c:4549 > #8 0x000055c24e0d259b in main (argc=24, argv=0x7ffff66b0d58, envp=0x7ffff66b0e20) at ../softmmu/main.c:51 > > Reported-by: Alex Bennée > Signed-off-by: Kevin Wolf Is this a race, or is there a chance of adding a reliable reproducer to qtest? Paolo