Message ID | 20180502100422.8688-3-peterx@redhat.com |
---|---|
State | New |
Headers | show |
Series | monitor: let Monitor be thread safe | expand |
* Peter Xu (peterx@redhat.com) wrote: > mon->fds were protected by BQL. Now protect it by mon_lock so that it > can even be used in monitor iothread. > > Signed-off-by: Peter Xu <peterx@redhat.com> > --- > monitor.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/monitor.c b/monitor.c > index 48882d28ae..9f361ec21e 100644 > --- a/monitor.c > +++ b/monitor.c > @@ -213,7 +213,6 @@ struct Monitor { > BlockCompletionFunc *password_completion_cb; > void *password_opaque; > mon_cmd_t *cmd_table; > - QLIST_HEAD(,mon_fd_t) fds; > QTAILQ_ENTRY(Monitor) entry; > > /* > @@ -225,6 +224,7 @@ struct Monitor { > /* > * Fields that are protected by the per-monitor lock. > */ > + QLIST_HEAD(, mon_fd_t) fds; > QString *outbuf; > guint out_watch; > /* Read under either BQL or mon_lock, written with BQL+mon_lock. */ > @@ -2207,6 +2207,7 @@ void qmp_getfd(const char *fdname, Error **errp) > return; > } > > + qemu_mutex_lock(&cur_mon->mon_lock); > QLIST_FOREACH(monfd, &cur_mon->fds, next) { > if (strcmp(monfd->name, fdname) != 0) { > continue; > @@ -2214,6 +2215,7 @@ void qmp_getfd(const char *fdname, Error **errp) > > close(monfd->fd); > monfd->fd = fd; > + qemu_mutex_unlock(&cur_mon->mon_lock); Why is it safe to have a close() in a mon_lock'd region? We've got to make sure everything that happens in it is non-blocking. Dave > return; > } > > @@ -2222,12 +2224,14 @@ void qmp_getfd(const char *fdname, Error **errp) > monfd->fd = fd; > > QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next); > + qemu_mutex_unlock(&cur_mon->mon_lock); > } > > void qmp_closefd(const char *fdname, Error **errp) > { > mon_fd_t *monfd; > > + qemu_mutex_lock(&cur_mon->mon_lock); > QLIST_FOREACH(monfd, &cur_mon->fds, next) { > if (strcmp(monfd->name, fdname) != 0) { > continue; > @@ -2237,9 +2241,11 @@ void qmp_closefd(const char *fdname, Error **errp) > close(monfd->fd); > g_free(monfd->name); > g_free(monfd); > + qemu_mutex_unlock(&cur_mon->mon_lock); > return; > } > > + qemu_mutex_unlock(&cur_mon->mon_lock); > error_setg(errp, QERR_FD_NOT_FOUND, fdname); > } > > @@ -2247,6 +2253,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) > { > mon_fd_t *monfd; > > + qemu_mutex_lock(&mon->mon_lock); > QLIST_FOREACH(monfd, &mon->fds, next) { > int fd; > > @@ -2260,10 +2267,12 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) > QLIST_REMOVE(monfd, next); > g_free(monfd->name); > g_free(monfd); > + qemu_mutex_unlock(&mon->mon_lock); > > return fd; > } > > + qemu_mutex_unlock(&mon->mon_lock); > error_setg(errp, "File descriptor named '%s' has not been found", fdname); > return -1; > } > -- > 2.14.3 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On Wed, May 02, 2018 at 12:15:07PM +0100, Dr. David Alan Gilbert wrote: > * Peter Xu (peterx@redhat.com) wrote: > > mon->fds were protected by BQL. Now protect it by mon_lock so that it > > can even be used in monitor iothread. > > > > Signed-off-by: Peter Xu <peterx@redhat.com> > > --- > > monitor.c | 11 ++++++++++- > > 1 file changed, 10 insertions(+), 1 deletion(-) > > > > diff --git a/monitor.c b/monitor.c > > index 48882d28ae..9f361ec21e 100644 > > --- a/monitor.c > > +++ b/monitor.c > > @@ -213,7 +213,6 @@ struct Monitor { > > BlockCompletionFunc *password_completion_cb; > > void *password_opaque; > > mon_cmd_t *cmd_table; > > - QLIST_HEAD(,mon_fd_t) fds; > > QTAILQ_ENTRY(Monitor) entry; > > > > /* > > @@ -225,6 +224,7 @@ struct Monitor { > > /* > > * Fields that are protected by the per-monitor lock. > > */ > > + QLIST_HEAD(, mon_fd_t) fds; > > QString *outbuf; > > guint out_watch; > > /* Read under either BQL or mon_lock, written with BQL+mon_lock. */ > > @@ -2207,6 +2207,7 @@ void qmp_getfd(const char *fdname, Error **errp) > > return; > > } > > > > + qemu_mutex_lock(&cur_mon->mon_lock); > > QLIST_FOREACH(monfd, &cur_mon->fds, next) { > > if (strcmp(monfd->name, fdname) != 0) { > > continue; > > @@ -2214,6 +2215,7 @@ void qmp_getfd(const char *fdname, Error **errp) > > > > close(monfd->fd); > > monfd->fd = fd; > > + qemu_mutex_unlock(&cur_mon->mon_lock); > > Why is it safe to have a close() in a mon_lock'd region? > We've got to make sure everything that happens in it is non-blocking. Hmm indeed. Let me move that close() out of the critical section. I think I need to touch up below [1] too since it'll has similar problem. I'll wait for some more comments to repost. Thanks, > > Dave > > > return; > > } > > > > @@ -2222,12 +2224,14 @@ void qmp_getfd(const char *fdname, Error **errp) > > monfd->fd = fd; > > > > QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next); > > + qemu_mutex_unlock(&cur_mon->mon_lock); > > } > > > > void qmp_closefd(const char *fdname, Error **errp) > > { > > mon_fd_t *monfd; > > > > + qemu_mutex_lock(&cur_mon->mon_lock); > > QLIST_FOREACH(monfd, &cur_mon->fds, next) { > > if (strcmp(monfd->name, fdname) != 0) { > > continue; > > @@ -2237,9 +2241,11 @@ void qmp_closefd(const char *fdname, Error **errp) > > close(monfd->fd); > > g_free(monfd->name); > > g_free(monfd); > > + qemu_mutex_unlock(&cur_mon->mon_lock); [1] > > return; > > } > > > > + qemu_mutex_unlock(&cur_mon->mon_lock); > > error_setg(errp, QERR_FD_NOT_FOUND, fdname); > > } > > > > @@ -2247,6 +2253,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) > > { > > mon_fd_t *monfd; > > > > + qemu_mutex_lock(&mon->mon_lock); > > QLIST_FOREACH(monfd, &mon->fds, next) { > > int fd; > > > > @@ -2260,10 +2267,12 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) > > QLIST_REMOVE(monfd, next); > > g_free(monfd->name); > > g_free(monfd); > > + qemu_mutex_unlock(&mon->mon_lock); > > > > return fd; > > } > > > > + qemu_mutex_unlock(&mon->mon_lock); > > error_setg(errp, "File descriptor named '%s' has not been found", fdname); > > return -1; > > } > > -- > > 2.14.3 > > > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/monitor.c b/monitor.c index 48882d28ae..9f361ec21e 100644 --- a/monitor.c +++ b/monitor.c @@ -213,7 +213,6 @@ struct Monitor { BlockCompletionFunc *password_completion_cb; void *password_opaque; mon_cmd_t *cmd_table; - QLIST_HEAD(,mon_fd_t) fds; QTAILQ_ENTRY(Monitor) entry; /* @@ -225,6 +224,7 @@ struct Monitor { /* * Fields that are protected by the per-monitor lock. */ + QLIST_HEAD(, mon_fd_t) fds; QString *outbuf; guint out_watch; /* Read under either BQL or mon_lock, written with BQL+mon_lock. */ @@ -2207,6 +2207,7 @@ void qmp_getfd(const char *fdname, Error **errp) return; } + qemu_mutex_lock(&cur_mon->mon_lock); QLIST_FOREACH(monfd, &cur_mon->fds, next) { if (strcmp(monfd->name, fdname) != 0) { continue; @@ -2214,6 +2215,7 @@ void qmp_getfd(const char *fdname, Error **errp) close(monfd->fd); monfd->fd = fd; + qemu_mutex_unlock(&cur_mon->mon_lock); return; } @@ -2222,12 +2224,14 @@ void qmp_getfd(const char *fdname, Error **errp) monfd->fd = fd; QLIST_INSERT_HEAD(&cur_mon->fds, monfd, next); + qemu_mutex_unlock(&cur_mon->mon_lock); } void qmp_closefd(const char *fdname, Error **errp) { mon_fd_t *monfd; + qemu_mutex_lock(&cur_mon->mon_lock); QLIST_FOREACH(monfd, &cur_mon->fds, next) { if (strcmp(monfd->name, fdname) != 0) { continue; @@ -2237,9 +2241,11 @@ void qmp_closefd(const char *fdname, Error **errp) close(monfd->fd); g_free(monfd->name); g_free(monfd); + qemu_mutex_unlock(&cur_mon->mon_lock); return; } + qemu_mutex_unlock(&cur_mon->mon_lock); error_setg(errp, QERR_FD_NOT_FOUND, fdname); } @@ -2247,6 +2253,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) { mon_fd_t *monfd; + qemu_mutex_lock(&mon->mon_lock); QLIST_FOREACH(monfd, &mon->fds, next) { int fd; @@ -2260,10 +2267,12 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) QLIST_REMOVE(monfd, next); g_free(monfd->name); g_free(monfd); + qemu_mutex_unlock(&mon->mon_lock); return fd; } + qemu_mutex_unlock(&mon->mon_lock); error_setg(errp, "File descriptor named '%s' has not been found", fdname); return -1; }
mon->fds were protected by BQL. Now protect it by mon_lock so that it can even be used in monitor iothread. Signed-off-by: Peter Xu <peterx@redhat.com> --- monitor.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)