diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2023-03-03 13:32:13 +0100 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2023-05-25 10:18:33 +0200 |
commit | 6ee7c82d0df9bb6e972a8ea689b935df3ba37486 (patch) | |
tree | f99a5786fb54b9072069e498313d4336bd9aaa6a /monitor | |
parent | 4cb96b974265f97a9902b4458e50d01082572a16 (diff) |
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 <pbonzini@redhat.com>
Diffstat (limited to 'monitor')
-rw-r--r-- | monitor/hmp.c | 35 | ||||
-rw-r--r-- | monitor/monitor-internal.h | 3 | ||||
-rw-r--r-- | monitor/monitor.c | 9 |
3 files changed, 24 insertions, 23 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"); + qemu_mutex_lock(&mon->mon_lock); + if (!mon->mux_out) { + if (mon->reset_seen && !mon->suspend_cnt) { + monitor_puts_locked(mon, "\n"); + } else { + monitor_flush_locked(mon); } - monitor_flush(mon); monitor_suspend(mon); - } else { - qatomic_inc(&mon->suspend_cnt); + mon->mux_out = 1; } - qemu_mutex_lock(&mon->mon_lock); - 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); + qemu_mutex_lock(&mon->mon_lock); + mon->reset_seen = 1; if (!mon->mux_out) { - readline_restart(hmp_mon->rs); - readline_show_prompt(hmp_mon->rs); + /* Suspend-resume forces the prompt to be printed. */ + monitor_suspend(mon); + monitor_resume(mon); } - mon->reset_seen = 1; + 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) |