Re: kern/54009: "l->l_pcu_cpu[id] == NULL" panic on aarch64

[Ryo Shimizu <ryo%nerv.org@localhost>]

The following reply was made to PR kern/54009; it has been noted by GNATS.

From: Ryo Shimizu <ryo%nerv.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
    netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/54009: "l->l_pcu_cpu[id] == NULL" panic on aarch64
Date: Mon, 26 Aug 2019 04:35:35 +0900

 I guess the cause is the lack of memory barrier.
 Will the following patches fix it?
 
 
 cvs -q diff -aup .
 Index: subr_ipi.c
 ===================================================================
 RCS file: /src/cvs/cvsroot-netbsd/src/sys/kern/subr_ipi.c,v
 retrieving revision 1.4
 diff -a -u -p -r1.4 subr_ipi.c
 --- subr_ipi.c	6 Apr 2019 02:59:05 -0000	1.4
 +++ subr_ipi.c	25 Aug 2019 19:23:47 -0000
 @@ -331,6 +331,9 @@ ipi_msg_cpu_handler(void *arg __unused)
  		msg->func(msg->arg);
  
  		/* Ack the request. */
 +#ifndef __HAVE_ATOMIC_AS_MEMBAR
 +		membar_producer();
 +#endif
  		atomic_dec_uint(&msg->_pending);
  	}
  }
 
 -- 
 ryo shimizu