From 6ee7c82d0df9bb6e972a8ea689b935df3ba37486 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 3 Mar 2023 13:32:13 +0100 Subject: [PATCH] monitor: do not use mb_read/mb_set for suspend_cnt Clean up monitor_event to just use monitor_suspend/monitor_resume, using mon->mux_out to protect against incorrect nesting (especially on startup). The only remaining case of reading suspend_cnt is in the can_read callback, which is just advisory and can use qatomic_read. As an extra benefit, mux_out is now simply protected by mon_lock. Also, moving the prompt to the beginning of the main loop removes it from the output in some error cases where QEMU does not actually start successfully. It is not a full fix and it would be nice to also remove the monitor heading, but this is already a small (though unintentional) improvement. Signed-off-by: Paolo Bonzini --- monitor/hmp.c | 41 ++++++++++++++++------------------- monitor/monitor-internal.h | 3 +-- monitor/monitor.c | 9 ++++++-- tests/qemu-iotests/051.out | 4 ++-- tests/qemu-iotests/051.pc.out | 20 ++++++++--------- 5 files changed, 39 insertions(+), 38 deletions(-) diff --git a/monitor/hmp.c b/monitor/hmp.c index 5cab56d355..69c1b7e98a 100644 --- a/monitor/hmp.c +++ b/monitor/hmp.c @@ -1401,45 +1401,42 @@ static void monitor_read(void *opaque, const uint8_t *buf, int size) static void monitor_event(void *opaque, QEMUChrEvent event) { Monitor *mon = opaque; - MonitorHMP *hmp_mon = container_of(mon, MonitorHMP, common); switch (event) { case CHR_EVENT_MUX_IN: qemu_mutex_lock(&mon->mon_lock); - mon->mux_out = 0; - qemu_mutex_unlock(&mon->mon_lock); - if (mon->reset_seen) { - readline_restart(hmp_mon->rs); + if (mon->mux_out) { + mon->mux_out = 0; monitor_resume(mon); - monitor_flush(mon); - } else { - qatomic_mb_set(&mon->suspend_cnt, 0); } + qemu_mutex_unlock(&mon->mon_lock); break; case CHR_EVENT_MUX_OUT: - if (mon->reset_seen) { - if (qatomic_mb_read(&mon->suspend_cnt) == 0) { - monitor_printf(mon, "\n"); - } - monitor_flush(mon); - monitor_suspend(mon); - } else { - qatomic_inc(&mon->suspend_cnt); - } qemu_mutex_lock(&mon->mon_lock); - mon->mux_out = 1; + if (!mon->mux_out) { + if (mon->reset_seen && !mon->suspend_cnt) { + monitor_puts_locked(mon, "\n"); + } else { + monitor_flush_locked(mon); + } + monitor_suspend(mon); + mon->mux_out = 1; + } qemu_mutex_unlock(&mon->mon_lock); break; case CHR_EVENT_OPENED: monitor_printf(mon, "QEMU %s monitor - type 'help' for more " "information\n", QEMU_VERSION); - if (!mon->mux_out) { - readline_restart(hmp_mon->rs); - readline_show_prompt(hmp_mon->rs); - } + qemu_mutex_lock(&mon->mon_lock); mon->reset_seen = 1; + if (!mon->mux_out) { + /* Suspend-resume forces the prompt to be printed. */ + monitor_suspend(mon); + monitor_resume(mon); + } + qemu_mutex_unlock(&mon->mon_lock); mon_refcount++; break; diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h index 53e3808054..61c9b6916d 100644 --- a/monitor/monitor-internal.h +++ b/monitor/monitor-internal.h @@ -94,7 +94,6 @@ typedef struct HMPCommand { struct Monitor { CharBackend chr; - int reset_seen; int suspend_cnt; /* Needs to be accessed atomically */ bool is_qmp; bool skip_flush; @@ -115,8 +114,8 @@ struct Monitor { QLIST_HEAD(, mon_fd_t) fds; GString *outbuf; guint out_watch; - /* Read under either BQL or mon_lock, written with BQL+mon_lock. */ int mux_out; + int reset_seen; }; struct MonitorHMP { diff --git a/monitor/monitor.c b/monitor/monitor.c index 20e33e28d2..15f97538ef 100644 --- a/monitor/monitor.c +++ b/monitor/monitor.c @@ -569,10 +569,15 @@ static void monitor_accept_input(void *opaque) { Monitor *mon = opaque; - if (!monitor_is_qmp(mon)) { + qemu_mutex_lock(&mon->mon_lock); + if (!monitor_is_qmp(mon) && mon->reset_seen) { MonitorHMP *hmp_mon = container_of(mon, MonitorHMP, common); assert(hmp_mon->rs); + readline_restart(hmp_mon->rs); + qemu_mutex_unlock(&mon->mon_lock); readline_show_prompt(hmp_mon->rs); + } else { + qemu_mutex_unlock(&mon->mon_lock); } qemu_chr_fe_accept_input(&mon->chr); @@ -603,7 +608,7 @@ int monitor_can_read(void *opaque) { Monitor *mon = opaque; - return !qatomic_mb_read(&mon->suspend_cnt); + return !qatomic_read(&mon->suspend_cnt); } void monitor_list_append(Monitor *mon) diff --git a/tests/qemu-iotests/051.out b/tests/qemu-iotests/051.out index e5ddb03bda..d462156405 100644 --- a/tests/qemu-iotests/051.out +++ b/tests/qemu-iotests/051.out @@ -74,7 +74,7 @@ QEMU_PROG: -drive file=TEST_DIR/t.qcow2,node-name=foo#12: Invalid node-name: 'fo Testing: -device virtio-scsi -device scsi-hd QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device scsi-hd: drive property not set +QEMU_PROG: -device scsi-hd: drive property not set === Overriding backing file === @@ -134,7 +134,7 @@ QEMU X.Y.Z monitor - type 'help' for more information Testing: -drive if=virtio QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -drive if=virtio: Device needs media, but drive is empty +QEMU_PROG: -drive if=virtio: Device needs media, but drive is empty === Attach to node in non-default iothread === diff --git a/tests/qemu-iotests/051.pc.out b/tests/qemu-iotests/051.pc.out index bade1ff3b9..4d4af5a486 100644 --- a/tests/qemu-iotests/051.pc.out +++ b/tests/qemu-iotests/051.pc.out @@ -74,7 +74,7 @@ QEMU_PROG: -drive file=TEST_DIR/t.qcow2,node-name=foo#12: Invalid node-name: 'fo Testing: -device virtio-scsi -device scsi-hd QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device scsi-hd: drive property not set +QEMU_PROG: -device scsi-hd: drive property not set === Overriding backing file === @@ -142,11 +142,11 @@ QEMU X.Y.Z monitor - type 'help' for more information Testing: -drive if=ide QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: Device needs media, but drive is empty +QEMU_PROG: Device needs media, but drive is empty Testing: -drive if=virtio QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -drive if=virtio: Device needs media, but drive is empty +QEMU_PROG: -drive if=virtio: Device needs media, but drive is empty Testing: -drive if=none,id=disk -device ide-cd,drive=disk QEMU X.Y.Z monitor - type 'help' for more information @@ -158,22 +158,22 @@ QEMU X.Y.Z monitor - type 'help' for more information Testing: -drive if=none,id=disk -device ide-hd,drive=disk QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device ide-hd,drive=disk: Device needs media, but drive is empty +QEMU_PROG: -device ide-hd,drive=disk: Device needs media, but drive is empty Testing: -drive if=none,id=disk -device lsi53c895a -device scsi-hd,drive=disk QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device scsi-hd,drive=disk: Device needs media, but drive is empty +QEMU_PROG: -device scsi-hd,drive=disk: Device needs media, but drive is empty === Attach to node in non-default iothread === Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device ide-hd,drive=disk,share-rw=on QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device ide-hd,drive=disk,share-rw=on: Cannot change iothread of active block backend +QEMU_PROG: -device ide-hd,drive=disk,share-rw=on: Cannot change iothread of active block backend Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-blk-pci,drive=disk,share-rw=on QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device virtio-blk-pci,drive=disk,share-rw=on: Cannot change iothread of active block backend +QEMU_PROG: -device virtio-blk-pci,drive=disk,share-rw=on: Cannot change iothread of active block backend Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device lsi53c895a,id=lsi0 -device scsi-hd,bus=lsi0.0,drive=disk,share-rw=on QEMU X.Y.Z monitor - type 'help' for more information @@ -185,7 +185,7 @@ QEMU X.Y.Z monitor - type 'help' for more information Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-blk-pci,drive=disk,iothread=thread0,share-rw=on QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device virtio-blk-pci,drive=disk,iothread=thread0,share-rw=on: Cannot change iothread of active block backend +QEMU_PROG: -device virtio-blk-pci,drive=disk,iothread=thread0,share-rw=on: Cannot change iothread of active block backend Testing: -drive file=TEST_DIR/t.qcow2,if=none,node-name=disk -object iothread,id=thread0 -device virtio-scsi,iothread=thread0,id=virtio-scsi0 -device scsi-hd,bus=virtio-scsi0.0,drive=disk,share-rw=on -device virtio-scsi,id=virtio-scsi1,iothread=thread0 -device scsi-hd,bus=virtio-scsi1.0,drive=disk,share-rw=on QEMU X.Y.Z monitor - type 'help' for more information @@ -204,7 +204,7 @@ QEMU X.Y.Z monitor - type 'help' for more information Testing: -drive file=TEST_DIR/t.qcow2,if=ide,readonly=on QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: Block node is read-only +QEMU_PROG: Block node is read-only Testing: -drive file=TEST_DIR/t.qcow2,if=virtio,readonly=on QEMU X.Y.Z monitor - type 'help' for more information @@ -220,7 +220,7 @@ QEMU X.Y.Z monitor - type 'help' for more information Testing: -drive file=TEST_DIR/t.qcow2,if=none,id=disk,readonly=on -device ide-hd,drive=disk QEMU X.Y.Z monitor - type 'help' for more information -(qemu) QEMU_PROG: -device ide-hd,drive=disk: Block node is read-only +QEMU_PROG: -device ide-hd,drive=disk: Block node is read-only Testing: -drive file=TEST_DIR/t.qcow2,if=none,id=disk,readonly=on -device lsi53c895a -device scsi-hd,drive=disk QEMU X.Y.Z monitor - type 'help' for more information