Re: port-mips/52892: Tests hang on MIPS

[christos%zoulas.com@localhost (Christos Zoulas)]

The following reply was made to PR port-mips/52892; it has been noted by GNATS.

From: christos%zoulas.com@localhost (Christos Zoulas)
To: Andreas Gustafsson <gson%gson.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost
Subject: Re: port-mips/52892: Tests hang on MIPS
Date: Sun, 22 Apr 2018 12:13:01 -0400

 On Apr 22,  5:29pm, gson%gson.org@localhost (Andreas Gustafsson) wrote:
 -- Subject: Re: port-mips/52892: Tests hang on MIPS
 
 | Christos Zoulas wrote:
 | > Can you try to always set errno to EAGAIN after cv_wait_sig()
 | > returns?
 | 
 | My other method of reproducing the hang took a bit longer than
 | expected, so in the meantime, I ended up running this test as
 | requested after all.  I applied the following patch to
 | 2018.04.20.11.31.54 sources:
 | 
 | --- src/sys/kern/kern_lwp.c.orig	2017-12-02 22:51:22.000000000 +0000
 | +++ src/sys/kern/kern_lwp.c	2018-04-22 14:19:14.000000000 +0000
 | @@ -646,8 +646,7 @@
 |  		if (exiting) {
 |  			KASSERT(p->p_nlwps > 1);
 |  			error = cv_wait_sig(&p->p_lwpcv, p->p_lock);
 | -			if (error == 0)
 | -				error = EAGAIN;
 | +			error = EAGAIN;
 |  			break;
 |  		}
 |  
 | With this patch, the hang still occurs, so it looks like the problem
 | is with the part of kern_lwp.c 1.191 that replaces cv_wait() by
 | cv_wait_sig(), not the part that changes the errno returned.
 
 How about if we make cvs_wait_sig look like cv_wait?
 But that might break go again..
 
 christos
 
 Index: kern_condvar.c
 ===================================================================
 RCS file: /cvsroot/src/sys/kern/kern_condvar.c,v
 retrieving revision 1.41
 diff -u -r1.41 kern_condvar.c
 --- kern_condvar.c	30 Jan 2018 07:52:22 -0000	1.41
 +++ kern_condvar.c	22 Apr 2018 16:12:19 -0000
 @@ -268,9 +268,10 @@
  
  	KASSERT(mutex_owned(mtx));
  
 -	cv_enter(cv, mtx, l);
 +	CV_LOCKDEBUG_HANDOFF(l, cv);
  	error = sleepq_block(0, true);
 -	return cv_exit(cv, mtx, l, error);
 +	mutex_enter(mtx);
 +	return error;
  }
  
  /*