[lxc-devel] [PATCH] make process_lock return void

Stéphane Graber stgraber at ubuntu.com
Mon Sep 16 19:59:45 UTC 2013


On Mon, Sep 16, 2013 at 02:58:51PM -0500, Serge Hallyn wrote:
> Quoting Serge Hallyn (serge.hallyn at ubuntu.com):
> > pthread_mutex_lock() will only return an error if it was set to
> > PTHREAD_MUTEX_ERRORCHECK and we are recursively calling it (and
> > would otherwise have deadlocked).  If that's the case then log a
> > message for future debugging and exit.  Trying to "recover" at
> > that point is madness.
> 
> Heh, all right this patch doesn't compile.  But assuming noone
> objects to the spirit of it I'll push one that does compile in
> a bit.  (It's the base of the more general thread-safety patch
> I'm working on)

I'm fine with the idea behind that patch.

> 
> > Signed-off-by: Serge Hallyn <serge.hallyn at ubuntu.com>
> > ---
> >  src/lxc/console.c      | 16 ++++++++--------
> >  src/lxc/lxccontainer.c | 12 ++++--------
> >  src/lxc/lxclock.c      |  6 ++++--
> >  src/lxc/lxclock.h      |  2 +-
> >  src/lxc/monitor.c      |  2 ++
> >  5 files changed, 19 insertions(+), 19 deletions(-)
> > 
> > diff --git a/src/lxc/console.c b/src/lxc/console.c
> > index e35a811..f503f18 100644
> > --- a/src/lxc/console.c
> > +++ b/src/lxc/console.c
> > @@ -100,16 +100,16 @@ static void lxc_console_winch(struct lxc_tty_state *ts)
> >  
> >  void lxc_console_sigwinch(int sig)
> >  {
> > -	if (process_lock() == 0) {
> > -		struct lxc_list *it;
> > -		struct lxc_tty_state *ts;
> > +	struct lxc_list *it;
> > +	struct lxc_tty_state *ts;
> >  
> > -		lxc_list_for_each(it, &lxc_ttys) {
> > -			ts = it->elem;
> > -			lxc_console_winch(ts);
> > -		}
> > -		process_unlock();
> > +	process_lock();
> > +
> > +	lxc_list_for_each(it, &lxc_ttys) {
> > +		ts = it->elem;
> > +		lxc_console_winch(ts);
> >  	}
> > +	process_unlock();
> >  }
> >  
> >  static int lxc_console_cb_sigwinch_fd(int fd, void *cbdata,
> > diff --git a/src/lxc/lxccontainer.c b/src/lxc/lxccontainer.c
> > index 3c51c4a..bb2f226 100644
> > --- a/src/lxc/lxccontainer.c
> > +++ b/src/lxc/lxccontainer.c
> > @@ -100,8 +100,7 @@ int ongoing_create(struct lxc_container *c)
> >  
> >  	if (!file_exists(path))
> >  		return 0;
> > -	if (process_lock())
> > -		return -1;
> > +	process_lock();
> >  	if ((fd = open(path, O_RDWR)) < 0) {
> >  		// give benefit of the doubt
> >  		SYSERROR("Error opening partial file");
> > @@ -138,8 +137,7 @@ int create_partial(struct lxc_container *c)
> >  		ERROR("Error writing partial pathname");
> >  		return -1;
> >  	}
> > -	if (process_lock())
> > -		return -1;
> > +	process_lock();
> >  	if ((fd=open(path, O_RDWR | O_CREAT | O_EXCL, 0755)) < 0) {
> >  		SYSERROR("Erorr creating partial file");
> >  		process_unlock();
> > @@ -173,8 +171,7 @@ void remove_partial(struct lxc_container *c, int fd)
> >  		ERROR("Error writing partial pathname");
> >  		return;
> >  	}
> > -	if (process_lock())
> > -		return;
> > +	process_lock();
> >  	if (unlink(path) < 0)
> >  		SYSERROR("Error unlink partial file %s", path);
> >  	process_unlock();
> > @@ -546,8 +543,7 @@ static bool lxcapi_start(struct lxc_container *c, int useinit, char * const argv
> >  			return false;
> >  		lxc_monitord_spawn(c->config_path);
> >  
> > -		if (process_lock())
> > -			return false;
> > +		process_lock();
> >  		pid_t pid = fork();
> >  		if (pid < 0) {
> >  			lxc_container_put(c);
> > diff --git a/src/lxc/lxclock.c b/src/lxc/lxclock.c
> > index 1d6a86c..3307418 100644
> > --- a/src/lxc/lxclock.c
> > +++ b/src/lxc/lxclock.c
> > @@ -271,12 +271,14 @@ void lxc_putlock(struct lxc_lock *l)
> >  	free(l);
> >  }
> >  
> > -int process_lock(void)
> > +void process_lock(void)
> >  {
> >  	int ret;
> >  	ret = pthread_mutex_lock(&thread_mutex);
> > -	if (ret != 0)
> > +	if (ret != 0) {
> >  		ERROR("pthread_mutex_lock returned:%d %s", ret, strerror(ret));
> > +		exit(1);
> > +	}
> >  	return ret;
> >  }
> >  
> > diff --git a/src/lxc/lxclock.h b/src/lxc/lxclock.h
> > index fae7e4d..dcdf79d 100644
> > --- a/src/lxc/lxclock.h
> > +++ b/src/lxc/lxclock.h
> > @@ -85,7 +85,7 @@ extern int lxcunlock(struct lxc_lock *lock);
> >  
> >  extern void lxc_putlock(struct lxc_lock *l);
> >  
> > -extern int process_lock(void);
> > +extern void process_lock(void);
> >  extern void process_unlock(void);
> >  struct lxc_container;
> >  extern int container_mem_lock(struct lxc_container *c);
> > diff --git a/src/lxc/monitor.c b/src/lxc/monitor.c
> > index 64e9987..747d6ca 100644
> > --- a/src/lxc/monitor.c
> > +++ b/src/lxc/monitor.c
> > @@ -187,7 +187,9 @@ int lxc_monitor_open(const char *lxcpath)
> >  	if (lxc_monitor_sock_name(lxcpath, &addr) < 0)
> >  		return -1;
> >  
> > +	process_lock();
> >  	fd = socket(PF_UNIX, SOCK_STREAM, 0);
> > +	process_unlock();
> >  	if (fd < 0) {
> >  		ERROR("socket : %s", strerror(errno));
> >  		return -1;
> > -- 
> > 1.8.3.2
> > 
> > 
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-- 
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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