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[88.187.86.199]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ad1894c01c9sm105502566b.105.2025.05.02.15.06.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 May 2025 15:06:33 -0700 (PDT) Message-ID: Date: Sat, 3 May 2025 00:06:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] monitor: don't wake up qmp_dispatcher_co coroutine upon cleanup To: andrey.drobyshev@virtuozzo.com, qemu-devel@nongnu.org Cc: armbru@redhat.com, pbonzini@redhat.com, den@virtuozzo.com, qemu-block References: <20250502214729.928380-1-andrey.drobyshev@virtuozzo.com> <20250502214729.928380-2-andrey.drobyshev@virtuozzo.com> Content-Language: en-US From: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= In-Reply-To: <20250502214729.928380-2-andrey.drobyshev@virtuozzo.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=2a00:1450:4864:20::62d; envelope-from=philmd@linaro.org; helo=mail-ej1-x62d.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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 2/5/25 23:47, andrey.drobyshev@virtuozzo.com wrote: > From: Andrey Drobyshev > > Since the commit 3e6bed61 ("monitor: cleanup detection of qmp_dispatcher_co > shutting down"), coroutine pointer qmp_dispatcher_co is set to NULL upon > cleanup. If a QMP command is sent after monitor_cleanup() (e.g. after > shutdown), this may lead to SEGFAULT on aio_co_wake(NULL). > > As mentioned in the comment inside monitor_cleanup(), the intention is to > allow incoming requests while shutting down, but simply leave them > without any response. Let's do exactly that, and if qmp_dispatcher_co > coroutine pointer has already been set to NULL, let's simply skip the > aio_co_wake() part. > Cc: qemu-stable@nongnu.org > Signed-off-by: Andrey Drobyshev > --- > monitor/qmp.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/monitor/qmp.c b/monitor/qmp.c > index 2f46cf9e49..cb99a12d94 100644 > --- a/monitor/qmp.c > +++ b/monitor/qmp.c > @@ -356,7 +356,8 @@ void qmp_dispatcher_co_wake(void) > /* Write request before reading qmp_dispatcher_co_busy. */ > smp_mb__before_rmw(); > > - if (!qatomic_xchg(&qmp_dispatcher_co_busy, true)) { > + if (!qatomic_xchg(&qmp_dispatcher_co_busy, true) && > + qatomic_read(&qmp_dispatcher_co)) { > aio_co_wake(qmp_dispatcher_co); > } > }