Don't needlessly poll file descriptors when there are no

file descriptors needing to be polled (Doh!).  Reported
by Dan Nelson <dnelson@emsphone.com>.

Don't install and start the scheduling timer until the
first thread is created.  This prevents the overhead of
having a periodic scheduling signal in a single threaded
program.  Reported by Dan Nelson <dnelson@emsphone.com>.

Allow builtin longjmps out of application installed
signal handlers without the need perform any post-handler
cleanup:

  o Change signal handling to save the threads interrupted
    context on the stack.  The threads current context is
    now always stored in the same place (in the pthread).
    If and when a signal handler returns, the interrupted
    context is copied back to the storage area in the pthread.

  o Before calling invoking a signal handler for a thread,
    back the thread out of any internal waiting queues
    (mutex, CV, join, etc) to which it belongs.

Rework uthread_info.c a bit to make it easier to change
the format of a thread dump.

Use an alternal signal stack for the thread library's
signal handler.  This allows us to fiddle with the main
threads stack without fear of it being in use.

Reviewed by:	jasone

1 files changed, 38 insertions, 31 deletions

diff --git a/lib/libpthread/thread/thr_private.h b/lib/libpthread/thread/thr_private.h
index 5076510..e8fff12 100644
--- a/lib/libpthread/thread/thr_private.h
+++ b/lib/libpthread/thread/thr_private.h
@@ -327,6 +327,7 @@ struct pthread_cond {
 	pthread_mutex_t			c_mutex;
 	void				*c_data;
 	long				c_flags;
+	int				c_seqno;
 
 	/*
 	 * Lock for accesses to this structure.
@@ -351,7 +352,7 @@ struct pthread_cond_attr {
  */
 #define PTHREAD_COND_STATIC_INITIALIZER    \
 	{ COND_TYPE_FAST, TAILQ_INITIALIZER, NULL, NULL, \
-	0, _SPINLOCK_INITIALIZER }
+	0, 0, _SPINLOCK_INITIALIZER }
 
 /*
  * Semaphore definitions.
@@ -424,6 +425,9 @@ enum pthread_susp {
  */
 #define PTHREAD_STACK_INITIAL			0x100000
 
+/* Size of the scheduler stack: */
+#define SCHED_STACK_SIZE			PAGE_SIZE
+
 /*
  * Define the different priority ranges.  All applications have thread
  * priorities constrained within 0-31.  The threads library raises the
@@ -574,13 +578,20 @@ union pthread_wait_data {
  */
 typedef void	(*thread_continuation_t) (void *);
 
+struct pthread_signal_frame;
+
 struct pthread_state_data {
-	int			psd_interrupted;
+	struct pthread_signal_frame *psd_curframe;
 	sigset_t		psd_sigmask;
-	enum pthread_state	psd_state;
-	int			psd_flags;
 	struct timespec		psd_wakeup_time;
 	union pthread_wait_data psd_wait_data;
+	enum pthread_state	psd_state;
+	int			psd_flags;
+	int			psd_interrupted;
+	int			psd_longjmp_val;
+	int			psd_sigmask_seqno;
+	int			psd_signo;
+	int			psd_sig_defer_count;
 	/* XXX - What about thread->timeout and/or thread->error? */
 };
 
@@ -620,9 +631,6 @@ struct pthread_signal_frame {
 	 */
 	struct pthread_state_data saved_state;
 
-	/* Beginning (bottom) of threads stack frame for this signal. */
-	unsigned long		stackp;
-
 	/*
 	 * Threads return context; ctxtype identifies the type of context.
 	 * For signal frame 0, these point to the context storage area
@@ -637,18 +645,10 @@ struct pthread_signal_frame {
 	} ctx;
 	thread_context_t	ctxtype;
 	int			longjmp_val;
-
-	/* Threads "jump out of signal handler" destination frame. */
-	int			dst_frame;
-
-	/*
-	 * Used to return back to the signal handling frame in case
-	 * the application tries to change contexts from the handler.
-	 */
-	jmp_buf			*sig_jb;
-
 	int			signo;	/* signal, arg 1 to sighandler */
 	int			sig_has_args;	/* use signal args if true */
+	ucontext_t		uc;
+	siginfo_t		siginfo;
 };
 
 /*
@@ -685,18 +685,20 @@ struct pthread {
 	struct pthread_attr	attr;
 
 	/*
-	 * Used for tracking delivery of nested signal handlers.
-	 * Signal frame 0 is used for normal context (when no
-	 * signal handlers are active for the thread).  Frame
-	 * 1 is used as the context for the first signal, and
-	 * frames 2 .. NSIG-1 are used when additional signals
-	 * arrive interrupting already active signal handlers.
+	 * Threads return context; ctxtype identifies the type of context.
+	 */
+	union {
+		jmp_buf		jb;
+		sigjmp_buf	sigjb;
+		ucontext_t	uc;
+	} ctx;
+	thread_context_t	ctxtype;
+	int			longjmp_val;
+
+	/*
+	 * Used for tracking delivery of signal handlers.
 	 */
-	struct pthread_signal_frame	*sigframes[NSIG];
-	struct pthread_signal_frame	sigframe0;
 	struct pthread_signal_frame	*curframe;
-	int	sigframe_count;
-	int	sigframe_done;
 
  	/*
 	 * Cancelability flags - the lower 2 bits are used by cancel
@@ -716,6 +718,7 @@ struct pthread {
 	 */
 	sigset_t	sigmask;
 	sigset_t	sigpend;
+	int		sigmask_seqno;
 	int		check_pending;
 
 	/* Thread state: */
@@ -1078,7 +1081,11 @@ SCLASS int	_thread_dfl_count[NSIG];
  * Pending signals and mask for this process:
  */
 SCLASS sigset_t	_process_sigpending;
-SCLASS sigset_t	_process_sigmask;
+SCLASS sigset_t	_process_sigmask
+#ifdef GLOBAL_PTHREAD_PRIVATE
+= { {0, 0, 0, 0} }
+#endif
+;
 
 /*
  * Scheduling queues:
@@ -1222,7 +1229,6 @@ void	_waitq_clearactive(void);
 #endif
 void    _thread_exit(char *, int, char *);
 void    _thread_exit_cleanup(void);
-void	_thread_exit_finish(void);
 void    _thread_fd_unlock(int, int);
 void    _thread_fd_unlock_debug(int, int, char *, int);
 void    _thread_fd_unlock_owned(pthread_t);
@@ -1232,7 +1238,7 @@ void    _thread_dump_info(void);
 void    _thread_init(void);
 void    _thread_kern_sched(ucontext_t *);
 void 	_thread_kern_scheduler(void);
-void    _thread_kern_sched_frame(int frame);
+void    _thread_kern_sched_frame(struct pthread_signal_frame *psf);
 void    _thread_kern_sched_sig(void);
 void    _thread_kern_sched_state(enum pthread_state, char *fname, int lineno);
 void	_thread_kern_sched_state_unlock(enum pthread_state state,
@@ -1245,7 +1251,7 @@ void    _thread_sig_check_pending(pthread_t pthread);
 void    _thread_sig_handle_pending(void);
 void	_thread_sig_send(pthread_t pthread, int sig);
 void	_thread_sig_wrapper(void);
-int	_thread_sigframe_find(pthread_t pthread, void *stackp);
+void	_thread_sigframe_restore(pthread_t thread, struct pthread_signal_frame *psf);
 void    _thread_start(void);
 void	_thread_seterrno(pthread_t, int);
 int     _thread_fd_table_init(int fd);
@@ -1262,6 +1268,7 @@ int     _thread_sys_sigsuspend(const sigset_t *);
 int     _thread_sys_siginterrupt(int, int);
 int     _thread_sys_sigpause(int);
 int     _thread_sys_sigreturn(ucontext_t *);
+int     _thread_sys_sigaltstack(const struct sigaltstack *, struct sigstack *);
 int     _thread_sys_sigstack(const struct sigstack *, struct sigstack *);
 int     _thread_sys_sigvec(int, struct sigvec *, struct sigvec *);
 void    _thread_sys_psignal(unsigned int, const char *);