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Wed, 9 Sep 2020 15:12:11 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-113-221.ams2.redhat.com [10.36.113.221]) by smtp.corp.redhat.com (Postfix) with ESMTP id B81E060C07; Wed, 9 Sep 2020 15:12:09 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PATCH v7 07/13] monitor: Make current monitor a per-coroutine property Date: Wed, 9 Sep 2020 17:11:43 +0200 Message-Id: <20200909151149.490589-8-kwolf@redhat.com> In-Reply-To: <20200909151149.490589-1-kwolf@redhat.com> References: <20200909151149.490589-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0.001 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=207.211.31.120; envelope-from=kwolf@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/09 03:05:47 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] 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, DKIMWL_WL_HIGH=-0.001, 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, 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: kwolf@redhat.com, qemu-devel@nongnu.org, armbru@redhat.com, marcandre.lureau@gmail.com, stefanha@redhat.com, dgilbert@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This way, a monitor command handler will still be able to access the current monitor, but when it yields, all other code code will correctly get NULL from monitor_cur(). This uses a hash table to map the coroutine pointer to the current monitor of that coroutine. Outside of coroutine context, we associate the current monitor with the leader coroutine of the current thread. Approaches to implement some form of coroutine local storage directly in the coroutine core code have been considered and discarded because they didn't end up being much more generic than the hash table and their performance impact on coroutines not using coroutine local storage was unclear. As the block layer uses a coroutine per I/O request, this is a fast path and we have to be careful. It's safest to just stay out of this path with code only used by the monitor. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- include/monitor/monitor.h | 2 +- monitor/hmp.c | 4 ++-- monitor/monitor.c | 34 +++++++++++++++++++++++++++------- qapi/qmp-dispatch.c | 4 ++-- stubs/monitor-core.c | 2 +- 5 files changed, 33 insertions(+), 13 deletions(-) diff --git a/include/monitor/monitor.h b/include/monitor/monitor.h index 7b0ad1de12..026f8a31b2 100644 --- a/include/monitor/monitor.h +++ b/include/monitor/monitor.h @@ -13,7 +13,7 @@ typedef struct MonitorOptions MonitorOptions; extern QemuOptsList qemu_mon_opts; Monitor *monitor_cur(void); -Monitor *monitor_set_cur(Monitor *mon); +Monitor *monitor_set_cur(Coroutine *co, Monitor *mon); bool monitor_cur_is_qmp(void); void monitor_init_globals(void); diff --git a/monitor/hmp.c b/monitor/hmp.c index 896c670183..4b66ca1cd6 100644 --- a/monitor/hmp.c +++ b/monitor/hmp.c @@ -1081,9 +1081,9 @@ void handle_hmp_command(MonitorHMP *mon, const char *cmdline) } /* old_mon is non-NULL when called from qmp_human_monitor_command() */ - old_mon = monitor_set_cur(&mon->common); + old_mon = monitor_set_cur(qemu_coroutine_self(), &mon->common); cmd->cmd(&mon->common, qdict); - monitor_set_cur(old_mon); + monitor_set_cur(qemu_coroutine_self(), old_mon); qobject_unref(qdict); } diff --git a/monitor/monitor.c b/monitor/monitor.c index be3839a7aa..629aa073ee 100644 --- a/monitor/monitor.c +++ b/monitor/monitor.c @@ -58,29 +58,48 @@ IOThread *mon_iothread; /* Bottom half to dispatch the requests received from I/O thread */ QEMUBH *qmp_dispatcher_bh; -/* Protects mon_list, monitor_qapi_event_state, monitor_destroyed. */ +/* + * Protects mon_list, monitor_qapi_event_state, coroutine_mon, + * monitor_destroyed. + */ QemuMutex monitor_lock; static GHashTable *monitor_qapi_event_state; +static GHashTable *coroutine_mon; /* Maps Coroutine* to Monitor* */ MonitorList mon_list; int mon_refcount; static bool monitor_destroyed; -static __thread Monitor *cur_monitor; - Monitor *monitor_cur(void) { - return cur_monitor; + Monitor *mon; + + qemu_mutex_lock(&monitor_lock); + mon = g_hash_table_lookup(coroutine_mon, qemu_coroutine_self()); + qemu_mutex_unlock(&monitor_lock); + + return mon; } /** * Sets a new current monitor and returns the old one. + * + * If a non-NULL monitor is set for a coroutine, another call resetting it to + * NULL is required before the coroutine terminates, otherwise a stale entry + * would remain in the hash table. */ -Monitor *monitor_set_cur(Monitor *mon) +Monitor *monitor_set_cur(Coroutine *co, Monitor *mon) { - Monitor *old_monitor = cur_monitor; + Monitor *old_monitor = monitor_cur(); + + qemu_mutex_lock(&monitor_lock); + if (mon) { + g_hash_table_replace(coroutine_mon, co, mon); + } else { + g_hash_table_remove(coroutine_mon, co); + } + qemu_mutex_unlock(&monitor_lock); - cur_monitor = mon; return old_monitor; } @@ -623,6 +642,7 @@ void monitor_init_globals_core(void) { monitor_qapi_event_init(); qemu_mutex_init(&monitor_lock); + coroutine_mon = g_hash_table_new(NULL, NULL); /* * The dispatcher BH must run in the main loop thread, since we diff --git a/qapi/qmp-dispatch.c b/qapi/qmp-dispatch.c index 2fdbc0fba4..5677ba92ca 100644 --- a/qapi/qmp-dispatch.c +++ b/qapi/qmp-dispatch.c @@ -154,11 +154,11 @@ QDict *qmp_dispatch(const QmpCommandList *cmds, QObject *request, } assert(monitor_cur() == NULL); - monitor_set_cur(cur_mon); + monitor_set_cur(qemu_coroutine_self(), cur_mon); cmd->fn(args, &ret, &err); - monitor_set_cur(NULL); + monitor_set_cur(qemu_coroutine_self(), NULL); qobject_unref(args); if (err) { /* or assert(!ret) after reviewing all handlers: */ diff --git a/stubs/monitor-core.c b/stubs/monitor-core.c index dc1748bf13..d058a2a00d 100644 --- a/stubs/monitor-core.c +++ b/stubs/monitor-core.c @@ -8,7 +8,7 @@ Monitor *monitor_cur(void) return NULL; } -Monitor *monitor_set_cur(Monitor *mon) +Monitor *monitor_set_cur(Coroutine *co, Monitor *mon) { return NULL; }