diff mbox series

[PULL,23/26] monitor: Use LOCK_GUARD macros

Message ID 20200925120655.295142-24-dgilbert@redhat.com
State Superseded
Headers show
Series migration and friends queue | expand

Commit Message

Dr. David Alan Gilbert Sept. 25, 2020, 12:06 p.m. UTC
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Use the lock guard macros in monitor/misc.c - saves
a lot of unlocks in error paths, and the occasional goto.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20200922095741.101911-1-dgilbert@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 monitor/misc.c | 44 ++++++++++++++------------------------------
 1 file changed, 14 insertions(+), 30 deletions(-)

Comments

Marc-André Lureau Feb. 7, 2023, 1:26 p.m. UTC | #1
Hi David

On Fri, Sep 25, 2020 at 4:27 PM Dr. David Alan Gilbert (git)
<dgilbert@redhat.com> wrote:
>
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> Use the lock guard macros in monitor/misc.c - saves
> a lot of unlocks in error paths, and the occasional goto.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Message-Id: <20200922095741.101911-1-dgilbert@redhat.com>
> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>  monitor/misc.c | 44 ++++++++++++++------------------------------
>  1 file changed, 14 insertions(+), 30 deletions(-)
>
> diff --git a/monitor/misc.c b/monitor/misc.c
> index 262f2bd951..6e0da0cb96 100644
> --- a/monitor/misc.c
> +++ b/monitor/misc.c
> @@ -141,13 +141,13 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
>      handle_hmp_command(&hmp, command_line);
>      cur_mon = old_mon;
>
> -    qemu_mutex_lock(&hmp.common.mon_lock);
> -    if (qstring_get_length(hmp.common.outbuf) > 0) {
> -        output = g_strdup(qstring_get_str(hmp.common.outbuf));
> -    } else {
> -        output = g_strdup("");
> +    WITH_QEMU_LOCK_GUARD(&hmp.common.mon_lock) {
> +        if (qstring_get_length(hmp.common.outbuf) > 0) {
> +            output = g_strdup(qstring_get_str(hmp.common.outbuf));
> +        } else {
> +            output = g_strdup("");
> +        }
>      }
> -    qemu_mutex_unlock(&hmp.common.mon_lock);
>
>  out:
>      monitor_data_destroy(&hmp.common);
> @@ -1248,7 +1248,7 @@ void qmp_getfd(const char *fdname, Error **errp)
>          return;
>      }
>
> -    qemu_mutex_lock(&cur_mon->mon_lock);
> +    QEMU_LOCK_GUARD(&cur_mon->mon_lock);
>      QLIST_FOREACH(monfd, &cur_mon->fds, next) {
>          if (strcmp(monfd->name, fdname) != 0) {
>              continue;
> @@ -1256,7 +1256,6 @@ void qmp_getfd(const char *fdname, Error **errp)
>
>          tmp_fd = monfd->fd;
>          monfd->fd = fd;
> -        qemu_mutex_unlock(&cur_mon->mon_lock);
>          /* Make sure close() is outside critical section */
>          close(tmp_fd);

The comment doesn't look true after this patch, since the lock is
released before returning. commit 9409fc05fe2 ("monitor: protect
mon->fds with mon_lock") introduced the lock & comment. Apparently,
you didn't convert qmp_closefd() to LOCK_GUARD, presumably because of
the comment. But you did it in qmp_getfd. What's the reason for that
though, avoiding syscalls while holding the lock or am I missing
something?

thanks

>          return;
> @@ -1267,7 +1266,6 @@ 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)
> @@ -1299,7 +1297,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
>  {
>      mon_fd_t *monfd;
>
> -    qemu_mutex_lock(&mon->mon_lock);
> +    QEMU_LOCK_GUARD(&mon->mon_lock);
>      QLIST_FOREACH(monfd, &mon->fds, next) {
>          int fd;
>
> @@ -1313,12 +1311,10 @@ 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;
>  }
> @@ -1350,11 +1346,10 @@ void monitor_fdsets_cleanup(void)
>      MonFdset *mon_fdset;
>      MonFdset *mon_fdset_next;
>
> -    qemu_mutex_lock(&mon_fdsets_lock);
> +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
>      QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) {
>          monitor_fdset_cleanup(mon_fdset);
>      }
> -    qemu_mutex_unlock(&mon_fdsets_lock);
>  }
>
>  AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
> @@ -1389,7 +1384,7 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
>      MonFdsetFd *mon_fdset_fd;
>      char fd_str[60];
>
> -    qemu_mutex_lock(&mon_fdsets_lock);
> +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
>      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
>          if (mon_fdset->id != fdset_id) {
>              continue;
> @@ -1409,12 +1404,10 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
>              goto error;
>          }
>          monitor_fdset_cleanup(mon_fdset);
> -        qemu_mutex_unlock(&mon_fdsets_lock);
>          return;
>      }
>
>  error:
> -    qemu_mutex_unlock(&mon_fdsets_lock);
>      if (has_fd) {
>          snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64 ", fd:%" PRId64,
>                   fdset_id, fd);
> @@ -1430,7 +1423,7 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
>      MonFdsetFd *mon_fdset_fd;
>      FdsetInfoList *fdset_list = NULL;
>
> -    qemu_mutex_lock(&mon_fdsets_lock);
> +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
>      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
>          FdsetInfoList *fdset_info = g_malloc0(sizeof(*fdset_info));
>          FdsetFdInfoList *fdsetfd_list = NULL;
> @@ -1460,7 +1453,6 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
>          fdset_info->next = fdset_list;
>          fdset_list = fdset_info;
>      }
> -    qemu_mutex_unlock(&mon_fdsets_lock);
>
>      return fdset_list;
>  }
> @@ -1554,7 +1546,7 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
>  #else
>      MonFdset *mon_fdset;
>
> -    qemu_mutex_lock(&mon_fdsets_lock);
> +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
>      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
>          MonFdsetFd *mon_fdset_fd;
>          MonFdsetFd *mon_fdset_fd_dup;
> @@ -1569,7 +1561,6 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
>          QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
>              mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
>              if (mon_fd_flags == -1) {
> -                qemu_mutex_unlock(&mon_fdsets_lock);
>                  return -1;
>              }
>
> @@ -1580,25 +1571,21 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
>          }
>
>          if (fd == -1) {
> -            qemu_mutex_unlock(&mon_fdsets_lock);
>              errno = EACCES;
>              return -1;
>          }
>
>          dup_fd = qemu_dup_flags(fd, flags);
>          if (dup_fd == -1) {
> -            qemu_mutex_unlock(&mon_fdsets_lock);
>              return -1;
>          }
>
>          mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
>          mon_fdset_fd_dup->fd = dup_fd;
>          QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
> -        qemu_mutex_unlock(&mon_fdsets_lock);
>          return dup_fd;
>      }
>
> -    qemu_mutex_unlock(&mon_fdsets_lock);
>      errno = ENOENT;
>      return -1;
>  #endif
> @@ -1609,7 +1596,7 @@ static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
>      MonFdset *mon_fdset;
>      MonFdsetFd *mon_fdset_fd_dup;
>
> -    qemu_mutex_lock(&mon_fdsets_lock);
> +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
>      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
>          QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
>              if (mon_fdset_fd_dup->fd == dup_fd) {
> @@ -1619,17 +1606,14 @@ static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
>                      if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
>                          monitor_fdset_cleanup(mon_fdset);
>                      }
> -                    goto err;
> +                    return -1;
>                  } else {
> -                    qemu_mutex_unlock(&mon_fdsets_lock);
>                      return mon_fdset->id;
>                  }
>              }
>          }
>      }
>
> -err:
> -    qemu_mutex_unlock(&mon_fdsets_lock);
>      return -1;
>  }
>
> --
> 2.26.2
>
>
Dr. David Alan Gilbert Feb. 7, 2023, 1:41 p.m. UTC | #2
* Marc-André Lureau (marcandre.lureau@gmail.com) wrote:
> Hi David
> 
> On Fri, Sep 25, 2020 at 4:27 PM Dr. David Alan Gilbert (git)
> <dgilbert@redhat.com> wrote:
> >
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> > Use the lock guard macros in monitor/misc.c - saves
> > a lot of unlocks in error paths, and the occasional goto.
> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > Message-Id: <20200922095741.101911-1-dgilbert@redhat.com>
> > Reviewed-by: Markus Armbruster <armbru@redhat.com>
> > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > ---
> >  monitor/misc.c | 44 ++++++++++++++------------------------------
> >  1 file changed, 14 insertions(+), 30 deletions(-)
> >
> > diff --git a/monitor/misc.c b/monitor/misc.c
> > index 262f2bd951..6e0da0cb96 100644
> > --- a/monitor/misc.c
> > +++ b/monitor/misc.c
> > @@ -141,13 +141,13 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
> >      handle_hmp_command(&hmp, command_line);
> >      cur_mon = old_mon;
> >
> > -    qemu_mutex_lock(&hmp.common.mon_lock);
> > -    if (qstring_get_length(hmp.common.outbuf) > 0) {
> > -        output = g_strdup(qstring_get_str(hmp.common.outbuf));
> > -    } else {
> > -        output = g_strdup("");
> > +    WITH_QEMU_LOCK_GUARD(&hmp.common.mon_lock) {
> > +        if (qstring_get_length(hmp.common.outbuf) > 0) {
> > +            output = g_strdup(qstring_get_str(hmp.common.outbuf));
> > +        } else {
> > +            output = g_strdup("");
> > +        }
> >      }
> > -    qemu_mutex_unlock(&hmp.common.mon_lock);
> >
> >  out:
> >      monitor_data_destroy(&hmp.common);
> > @@ -1248,7 +1248,7 @@ void qmp_getfd(const char *fdname, Error **errp)
> >          return;
> >      }
> >
> > -    qemu_mutex_lock(&cur_mon->mon_lock);
> > +    QEMU_LOCK_GUARD(&cur_mon->mon_lock);
> >      QLIST_FOREACH(monfd, &cur_mon->fds, next) {
> >          if (strcmp(monfd->name, fdname) != 0) {
> >              continue;
> > @@ -1256,7 +1256,6 @@ void qmp_getfd(const char *fdname, Error **errp)
> >
> >          tmp_fd = monfd->fd;
> >          monfd->fd = fd;
> > -        qemu_mutex_unlock(&cur_mon->mon_lock);
> >          /* Make sure close() is outside critical section */
> >          close(tmp_fd);
> 
> The comment doesn't look true after this patch, since the lock is
> released before returning. commit 9409fc05fe2 ("monitor: protect
> mon->fds with mon_lock") introduced the lock & comment. Apparently,
> you didn't convert qmp_closefd() to LOCK_GUARD, presumably because of
> the comment. But you did it in qmp_getfd. What's the reason for that
> though, avoiding syscalls while holding the lock or am I missing
> something?

No, I think you're right!
Yeh I think the reason was to avoid the (potentially blocking) syscall 
with the lock held.

Dave

> thanks
> 
> >          return;
> > @@ -1267,7 +1266,6 @@ 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)
> > @@ -1299,7 +1297,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
> >  {
> >      mon_fd_t *monfd;
> >
> > -    qemu_mutex_lock(&mon->mon_lock);
> > +    QEMU_LOCK_GUARD(&mon->mon_lock);
> >      QLIST_FOREACH(monfd, &mon->fds, next) {
> >          int fd;
> >
> > @@ -1313,12 +1311,10 @@ 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;
> >  }
> > @@ -1350,11 +1346,10 @@ void monitor_fdsets_cleanup(void)
> >      MonFdset *mon_fdset;
> >      MonFdset *mon_fdset_next;
> >
> > -    qemu_mutex_lock(&mon_fdsets_lock);
> > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> >      QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) {
> >          monitor_fdset_cleanup(mon_fdset);
> >      }
> > -    qemu_mutex_unlock(&mon_fdsets_lock);
> >  }
> >
> >  AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
> > @@ -1389,7 +1384,7 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
> >      MonFdsetFd *mon_fdset_fd;
> >      char fd_str[60];
> >
> > -    qemu_mutex_lock(&mon_fdsets_lock);
> > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> >          if (mon_fdset->id != fdset_id) {
> >              continue;
> > @@ -1409,12 +1404,10 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
> >              goto error;
> >          }
> >          monitor_fdset_cleanup(mon_fdset);
> > -        qemu_mutex_unlock(&mon_fdsets_lock);
> >          return;
> >      }
> >
> >  error:
> > -    qemu_mutex_unlock(&mon_fdsets_lock);
> >      if (has_fd) {
> >          snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64 ", fd:%" PRId64,
> >                   fdset_id, fd);
> > @@ -1430,7 +1423,7 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
> >      MonFdsetFd *mon_fdset_fd;
> >      FdsetInfoList *fdset_list = NULL;
> >
> > -    qemu_mutex_lock(&mon_fdsets_lock);
> > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> >          FdsetInfoList *fdset_info = g_malloc0(sizeof(*fdset_info));
> >          FdsetFdInfoList *fdsetfd_list = NULL;
> > @@ -1460,7 +1453,6 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
> >          fdset_info->next = fdset_list;
> >          fdset_list = fdset_info;
> >      }
> > -    qemu_mutex_unlock(&mon_fdsets_lock);
> >
> >      return fdset_list;
> >  }
> > @@ -1554,7 +1546,7 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
> >  #else
> >      MonFdset *mon_fdset;
> >
> > -    qemu_mutex_lock(&mon_fdsets_lock);
> > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> >          MonFdsetFd *mon_fdset_fd;
> >          MonFdsetFd *mon_fdset_fd_dup;
> > @@ -1569,7 +1561,6 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
> >          QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
> >              mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
> >              if (mon_fd_flags == -1) {
> > -                qemu_mutex_unlock(&mon_fdsets_lock);
> >                  return -1;
> >              }
> >
> > @@ -1580,25 +1571,21 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
> >          }
> >
> >          if (fd == -1) {
> > -            qemu_mutex_unlock(&mon_fdsets_lock);
> >              errno = EACCES;
> >              return -1;
> >          }
> >
> >          dup_fd = qemu_dup_flags(fd, flags);
> >          if (dup_fd == -1) {
> > -            qemu_mutex_unlock(&mon_fdsets_lock);
> >              return -1;
> >          }
> >
> >          mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
> >          mon_fdset_fd_dup->fd = dup_fd;
> >          QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
> > -        qemu_mutex_unlock(&mon_fdsets_lock);
> >          return dup_fd;
> >      }
> >
> > -    qemu_mutex_unlock(&mon_fdsets_lock);
> >      errno = ENOENT;
> >      return -1;
> >  #endif
> > @@ -1609,7 +1596,7 @@ static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
> >      MonFdset *mon_fdset;
> >      MonFdsetFd *mon_fdset_fd_dup;
> >
> > -    qemu_mutex_lock(&mon_fdsets_lock);
> > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> >          QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
> >              if (mon_fdset_fd_dup->fd == dup_fd) {
> > @@ -1619,17 +1606,14 @@ static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
> >                      if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
> >                          monitor_fdset_cleanup(mon_fdset);
> >                      }
> > -                    goto err;
> > +                    return -1;
> >                  } else {
> > -                    qemu_mutex_unlock(&mon_fdsets_lock);
> >                      return mon_fdset->id;
> >                  }
> >              }
> >          }
> >      }
> >
> > -err:
> > -    qemu_mutex_unlock(&mon_fdsets_lock);
> >      return -1;
> >  }
> >
> > --
> > 2.26.2
> >
> >
> 
> 
> -- 
> Marc-André Lureau
>
Marc-André Lureau Feb. 7, 2023, 2:06 p.m. UTC | #3
Hi

On Tue, Feb 7, 2023 at 5:41 PM Dr. David Alan Gilbert
<dgilbert@redhat.com> wrote:
>
> * Marc-André Lureau (marcandre.lureau@gmail.com) wrote:
> > Hi David
> >
> > On Fri, Sep 25, 2020 at 4:27 PM Dr. David Alan Gilbert (git)
> > <dgilbert@redhat.com> wrote:
> > >
> > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> > >
> > > Use the lock guard macros in monitor/misc.c - saves
> > > a lot of unlocks in error paths, and the occasional goto.
> > >
> > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > > Message-Id: <20200922095741.101911-1-dgilbert@redhat.com>
> > > Reviewed-by: Markus Armbruster <armbru@redhat.com>
> > > Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> > > ---
> > >  monitor/misc.c | 44 ++++++++++++++------------------------------
> > >  1 file changed, 14 insertions(+), 30 deletions(-)
> > >
> > > diff --git a/monitor/misc.c b/monitor/misc.c
> > > index 262f2bd951..6e0da0cb96 100644
> > > --- a/monitor/misc.c
> > > +++ b/monitor/misc.c
> > > @@ -141,13 +141,13 @@ char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
> > >      handle_hmp_command(&hmp, command_line);
> > >      cur_mon = old_mon;
> > >
> > > -    qemu_mutex_lock(&hmp.common.mon_lock);
> > > -    if (qstring_get_length(hmp.common.outbuf) > 0) {
> > > -        output = g_strdup(qstring_get_str(hmp.common.outbuf));
> > > -    } else {
> > > -        output = g_strdup("");
> > > +    WITH_QEMU_LOCK_GUARD(&hmp.common.mon_lock) {
> > > +        if (qstring_get_length(hmp.common.outbuf) > 0) {
> > > +            output = g_strdup(qstring_get_str(hmp.common.outbuf));
> > > +        } else {
> > > +            output = g_strdup("");
> > > +        }
> > >      }
> > > -    qemu_mutex_unlock(&hmp.common.mon_lock);
> > >
> > >  out:
> > >      monitor_data_destroy(&hmp.common);
> > > @@ -1248,7 +1248,7 @@ void qmp_getfd(const char *fdname, Error **errp)
> > >          return;
> > >      }
> > >
> > > -    qemu_mutex_lock(&cur_mon->mon_lock);
> > > +    QEMU_LOCK_GUARD(&cur_mon->mon_lock);
> > >      QLIST_FOREACH(monfd, &cur_mon->fds, next) {
> > >          if (strcmp(monfd->name, fdname) != 0) {
> > >              continue;
> > > @@ -1256,7 +1256,6 @@ void qmp_getfd(const char *fdname, Error **errp)
> > >
> > >          tmp_fd = monfd->fd;
> > >          monfd->fd = fd;
> > > -        qemu_mutex_unlock(&cur_mon->mon_lock);
> > >          /* Make sure close() is outside critical section */
> > >          close(tmp_fd);
> >
> > The comment doesn't look true after this patch, since the lock is
> > released before returning. commit 9409fc05fe2 ("monitor: protect
> > mon->fds with mon_lock") introduced the lock & comment. Apparently,
> > you didn't convert qmp_closefd() to LOCK_GUARD, presumably because of
> > the comment. But you did it in qmp_getfd. What's the reason for that
> > though, avoiding syscalls while holding the lock or am I missing
> > something?
>
> No, I think you're right!
> Yeh I think the reason was to avoid the (potentially blocking) syscall
> with the lock held.
>

Ok, I'll send a patch, thanks

> Dave
>
> > thanks
> >
> > >          return;
> > > @@ -1267,7 +1266,6 @@ 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)
> > > @@ -1299,7 +1297,7 @@ int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
> > >  {
> > >      mon_fd_t *monfd;
> > >
> > > -    qemu_mutex_lock(&mon->mon_lock);
> > > +    QEMU_LOCK_GUARD(&mon->mon_lock);
> > >      QLIST_FOREACH(monfd, &mon->fds, next) {
> > >          int fd;
> > >
> > > @@ -1313,12 +1311,10 @@ 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;
> > >  }
> > > @@ -1350,11 +1346,10 @@ void monitor_fdsets_cleanup(void)
> > >      MonFdset *mon_fdset;
> > >      MonFdset *mon_fdset_next;
> > >
> > > -    qemu_mutex_lock(&mon_fdsets_lock);
> > > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> > >      QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) {
> > >          monitor_fdset_cleanup(mon_fdset);
> > >      }
> > > -    qemu_mutex_unlock(&mon_fdsets_lock);
> > >  }
> > >
> > >  AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
> > > @@ -1389,7 +1384,7 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
> > >      MonFdsetFd *mon_fdset_fd;
> > >      char fd_str[60];
> > >
> > > -    qemu_mutex_lock(&mon_fdsets_lock);
> > > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> > >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> > >          if (mon_fdset->id != fdset_id) {
> > >              continue;
> > > @@ -1409,12 +1404,10 @@ void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
> > >              goto error;
> > >          }
> > >          monitor_fdset_cleanup(mon_fdset);
> > > -        qemu_mutex_unlock(&mon_fdsets_lock);
> > >          return;
> > >      }
> > >
> > >  error:
> > > -    qemu_mutex_unlock(&mon_fdsets_lock);
> > >      if (has_fd) {
> > >          snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64 ", fd:%" PRId64,
> > >                   fdset_id, fd);
> > > @@ -1430,7 +1423,7 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
> > >      MonFdsetFd *mon_fdset_fd;
> > >      FdsetInfoList *fdset_list = NULL;
> > >
> > > -    qemu_mutex_lock(&mon_fdsets_lock);
> > > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> > >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> > >          FdsetInfoList *fdset_info = g_malloc0(sizeof(*fdset_info));
> > >          FdsetFdInfoList *fdsetfd_list = NULL;
> > > @@ -1460,7 +1453,6 @@ FdsetInfoList *qmp_query_fdsets(Error **errp)
> > >          fdset_info->next = fdset_list;
> > >          fdset_list = fdset_info;
> > >      }
> > > -    qemu_mutex_unlock(&mon_fdsets_lock);
> > >
> > >      return fdset_list;
> > >  }
> > > @@ -1554,7 +1546,7 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
> > >  #else
> > >      MonFdset *mon_fdset;
> > >
> > > -    qemu_mutex_lock(&mon_fdsets_lock);
> > > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> > >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> > >          MonFdsetFd *mon_fdset_fd;
> > >          MonFdsetFd *mon_fdset_fd_dup;
> > > @@ -1569,7 +1561,6 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
> > >          QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
> > >              mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
> > >              if (mon_fd_flags == -1) {
> > > -                qemu_mutex_unlock(&mon_fdsets_lock);
> > >                  return -1;
> > >              }
> > >
> > > @@ -1580,25 +1571,21 @@ int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
> > >          }
> > >
> > >          if (fd == -1) {
> > > -            qemu_mutex_unlock(&mon_fdsets_lock);
> > >              errno = EACCES;
> > >              return -1;
> > >          }
> > >
> > >          dup_fd = qemu_dup_flags(fd, flags);
> > >          if (dup_fd == -1) {
> > > -            qemu_mutex_unlock(&mon_fdsets_lock);
> > >              return -1;
> > >          }
> > >
> > >          mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
> > >          mon_fdset_fd_dup->fd = dup_fd;
> > >          QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
> > > -        qemu_mutex_unlock(&mon_fdsets_lock);
> > >          return dup_fd;
> > >      }
> > >
> > > -    qemu_mutex_unlock(&mon_fdsets_lock);
> > >      errno = ENOENT;
> > >      return -1;
> > >  #endif
> > > @@ -1609,7 +1596,7 @@ static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
> > >      MonFdset *mon_fdset;
> > >      MonFdsetFd *mon_fdset_fd_dup;
> > >
> > > -    qemu_mutex_lock(&mon_fdsets_lock);
> > > +    QEMU_LOCK_GUARD(&mon_fdsets_lock);
> > >      QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
> > >          QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
> > >              if (mon_fdset_fd_dup->fd == dup_fd) {
> > > @@ -1619,17 +1606,14 @@ static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
> > >                      if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
> > >                          monitor_fdset_cleanup(mon_fdset);
> > >                      }
> > > -                    goto err;
> > > +                    return -1;
> > >                  } else {
> > > -                    qemu_mutex_unlock(&mon_fdsets_lock);
> > >                      return mon_fdset->id;
> > >                  }
> > >              }
> > >          }
> > >      }
> > >
> > > -err:
> > > -    qemu_mutex_unlock(&mon_fdsets_lock);
> > >      return -1;
> > >  }
> > >
> > > --
> > > 2.26.2
> > >
> > >
> >
> >
> > --
> > Marc-André Lureau
> >
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>
diff mbox series

Patch

diff --git a/monitor/misc.c b/monitor/misc.c
index 262f2bd951..6e0da0cb96 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -141,13 +141,13 @@  char *qmp_human_monitor_command(const char *command_line, bool has_cpu_index,
     handle_hmp_command(&hmp, command_line);
     cur_mon = old_mon;
 
-    qemu_mutex_lock(&hmp.common.mon_lock);
-    if (qstring_get_length(hmp.common.outbuf) > 0) {
-        output = g_strdup(qstring_get_str(hmp.common.outbuf));
-    } else {
-        output = g_strdup("");
+    WITH_QEMU_LOCK_GUARD(&hmp.common.mon_lock) {
+        if (qstring_get_length(hmp.common.outbuf) > 0) {
+            output = g_strdup(qstring_get_str(hmp.common.outbuf));
+        } else {
+            output = g_strdup("");
+        }
     }
-    qemu_mutex_unlock(&hmp.common.mon_lock);
 
 out:
     monitor_data_destroy(&hmp.common);
@@ -1248,7 +1248,7 @@  void qmp_getfd(const char *fdname, Error **errp)
         return;
     }
 
-    qemu_mutex_lock(&cur_mon->mon_lock);
+    QEMU_LOCK_GUARD(&cur_mon->mon_lock);
     QLIST_FOREACH(monfd, &cur_mon->fds, next) {
         if (strcmp(monfd->name, fdname) != 0) {
             continue;
@@ -1256,7 +1256,6 @@  void qmp_getfd(const char *fdname, Error **errp)
 
         tmp_fd = monfd->fd;
         monfd->fd = fd;
-        qemu_mutex_unlock(&cur_mon->mon_lock);
         /* Make sure close() is outside critical section */
         close(tmp_fd);
         return;
@@ -1267,7 +1266,6 @@  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)
@@ -1299,7 +1297,7 @@  int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp)
 {
     mon_fd_t *monfd;
 
-    qemu_mutex_lock(&mon->mon_lock);
+    QEMU_LOCK_GUARD(&mon->mon_lock);
     QLIST_FOREACH(monfd, &mon->fds, next) {
         int fd;
 
@@ -1313,12 +1311,10 @@  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;
 }
@@ -1350,11 +1346,10 @@  void monitor_fdsets_cleanup(void)
     MonFdset *mon_fdset;
     MonFdset *mon_fdset_next;
 
-    qemu_mutex_lock(&mon_fdsets_lock);
+    QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH_SAFE(mon_fdset, &mon_fdsets, next, mon_fdset_next) {
         monitor_fdset_cleanup(mon_fdset);
     }
-    qemu_mutex_unlock(&mon_fdsets_lock);
 }
 
 AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque,
@@ -1389,7 +1384,7 @@  void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
     MonFdsetFd *mon_fdset_fd;
     char fd_str[60];
 
-    qemu_mutex_lock(&mon_fdsets_lock);
+    QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         if (mon_fdset->id != fdset_id) {
             continue;
@@ -1409,12 +1404,10 @@  void qmp_remove_fd(int64_t fdset_id, bool has_fd, int64_t fd, Error **errp)
             goto error;
         }
         monitor_fdset_cleanup(mon_fdset);
-        qemu_mutex_unlock(&mon_fdsets_lock);
         return;
     }
 
 error:
-    qemu_mutex_unlock(&mon_fdsets_lock);
     if (has_fd) {
         snprintf(fd_str, sizeof(fd_str), "fdset-id:%" PRId64 ", fd:%" PRId64,
                  fdset_id, fd);
@@ -1430,7 +1423,7 @@  FdsetInfoList *qmp_query_fdsets(Error **errp)
     MonFdsetFd *mon_fdset_fd;
     FdsetInfoList *fdset_list = NULL;
 
-    qemu_mutex_lock(&mon_fdsets_lock);
+    QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         FdsetInfoList *fdset_info = g_malloc0(sizeof(*fdset_info));
         FdsetFdInfoList *fdsetfd_list = NULL;
@@ -1460,7 +1453,6 @@  FdsetInfoList *qmp_query_fdsets(Error **errp)
         fdset_info->next = fdset_list;
         fdset_list = fdset_info;
     }
-    qemu_mutex_unlock(&mon_fdsets_lock);
 
     return fdset_list;
 }
@@ -1554,7 +1546,7 @@  int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
 #else
     MonFdset *mon_fdset;
 
-    qemu_mutex_lock(&mon_fdsets_lock);
+    QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         MonFdsetFd *mon_fdset_fd;
         MonFdsetFd *mon_fdset_fd_dup;
@@ -1569,7 +1561,6 @@  int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
         QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {
             mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);
             if (mon_fd_flags == -1) {
-                qemu_mutex_unlock(&mon_fdsets_lock);
                 return -1;
             }
 
@@ -1580,25 +1571,21 @@  int monitor_fdset_dup_fd_add(int64_t fdset_id, int flags)
         }
 
         if (fd == -1) {
-            qemu_mutex_unlock(&mon_fdsets_lock);
             errno = EACCES;
             return -1;
         }
 
         dup_fd = qemu_dup_flags(fd, flags);
         if (dup_fd == -1) {
-            qemu_mutex_unlock(&mon_fdsets_lock);
             return -1;
         }
 
         mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));
         mon_fdset_fd_dup->fd = dup_fd;
         QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);
-        qemu_mutex_unlock(&mon_fdsets_lock);
         return dup_fd;
     }
 
-    qemu_mutex_unlock(&mon_fdsets_lock);
     errno = ENOENT;
     return -1;
 #endif
@@ -1609,7 +1596,7 @@  static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
     MonFdset *mon_fdset;
     MonFdsetFd *mon_fdset_fd_dup;
 
-    qemu_mutex_lock(&mon_fdsets_lock);
+    QEMU_LOCK_GUARD(&mon_fdsets_lock);
     QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {
         QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {
             if (mon_fdset_fd_dup->fd == dup_fd) {
@@ -1619,17 +1606,14 @@  static int64_t monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)
                     if (QLIST_EMPTY(&mon_fdset->dup_fds)) {
                         monitor_fdset_cleanup(mon_fdset);
                     }
-                    goto err;
+                    return -1;
                 } else {
-                    qemu_mutex_unlock(&mon_fdsets_lock);
                     return mon_fdset->id;
                 }
             }
         }
     }
 
-err:
-    qemu_mutex_unlock(&mon_fdsets_lock);
     return -1;
 }