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Tue, 14 Feb 2023 14:08:39 GMT Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5992620040; Tue, 14 Feb 2023 14:08:39 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CC26B20043; Tue, 14 Feb 2023 14:08:38 +0000 (GMT) Received: from heavy.boa-de.ibmmobiledemo.com (unknown [9.171.76.115]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 14 Feb 2023 14:08:38 +0000 (GMT) From: Ilya Leoshkevich To: Richard Henderson , Paolo Bonzini , Eduardo Habkost , Marcel Apfelbaum , =?utf-8?q?Philippe_Mathieu-D?= =?utf-8?q?aud=C3=A9?= , Yanan Wang , Laurent Vivier , =?utf-8?q?Alex_Benn=C3=A9e?= Cc: qemu-devel@nongnu.org, Christian Borntraeger , Ilya Leoshkevich Subject: [PATCH v4 2/4] cpus: Make {start,end}_exclusive() recursive Date: Tue, 14 Feb 2023 15:08:27 +0100 Message-Id: <20230214140829.45392-3-iii@linux.ibm.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230214140829.45392-1-iii@linux.ibm.com> References: <20230214140829.45392-1-iii@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: WXj9lWSsKnBlBOQXoXOCw30qLNtFLOwL X-Proofpoint-ORIG-GUID: 9xCFuN_XbeTNWmjZR9IfZwsFCGu98Ov_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.170.22 definitions=2023-02-14_07,2023-02-14_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 adultscore=0 mlxlogscore=972 malwarescore=0 mlxscore=0 spamscore=0 phishscore=0 impostorscore=0 clxscore=1015 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2302140120 Received-SPF: pass client-ip=148.163.156.1; envelope-from=iii@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, 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 Currently dying to one of the core_dump_signal()s deadlocks, because dump_core_and_abort() calls start_exclusive() two times: first via stop_all_tasks(), and then via preexit_cleanup() -> qemu_plugin_user_exit(). There are a number of ways to solve this: resume after dumping core; check cpu_in_exclusive_context() in qemu_plugin_user_exit(); or make {start,end}_exclusive() recursive. Pick the last option, since it's the most straightforward one. Fixes: da91c1920242 ("linux-user: Clean up when exiting due to a signal") Reviewed-by: Richard Henderson Reviewed-by: Alex Bennée Signed-off-by: Ilya Leoshkevich --- cpus-common.c | 12 ++++++++++-- include/hw/core/cpu.h | 4 ++-- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/cpus-common.c b/cpus-common.c index 793364dc0ed..39f355de989 100644 --- a/cpus-common.c +++ b/cpus-common.c @@ -192,6 +192,11 @@ void start_exclusive(void) CPUState *other_cpu; int running_cpus; + if (current_cpu->exclusive_context_count) { + current_cpu->exclusive_context_count++; + return; + } + qemu_mutex_lock(&qemu_cpu_list_lock); exclusive_idle(); @@ -219,13 +224,16 @@ void start_exclusive(void) */ qemu_mutex_unlock(&qemu_cpu_list_lock); - current_cpu->in_exclusive_context = true; + current_cpu->exclusive_context_count = 1; } /* Finish an exclusive operation. */ void end_exclusive(void) { - current_cpu->in_exclusive_context = false; + current_cpu->exclusive_context_count--; + if (current_cpu->exclusive_context_count) { + return; + } qemu_mutex_lock(&qemu_cpu_list_lock); qatomic_set(&pending_cpus, 0); diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index 2417597236b..671f041bec6 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -349,7 +349,7 @@ struct CPUState { bool unplug; bool crash_occurred; bool exit_request; - bool in_exclusive_context; + int exclusive_context_count; uint32_t cflags_next_tb; /* updates protected by BQL */ uint32_t interrupt_request; @@ -758,7 +758,7 @@ void async_safe_run_on_cpu(CPUState *cpu, run_on_cpu_func func, run_on_cpu_data */ static inline bool cpu_in_exclusive_context(const CPUState *cpu) { - return cpu->in_exclusive_context; + return cpu->exclusive_context_count; } /**