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Date: Fri, 10 Jan 2003 20:41:42 +0100 (CET)
From: Stefan Esser <se@FreeBSD.org>
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To: FreeBSD-gnats-submit@freebsd.org
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>Number:         46957
>Category:       kern
>Synopsis:       [Patch] Bogus return value (-1==ERESTART) of ksem_close() causes infinite loop.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    alfred
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Jan 10 11:50:01 PST 2003
>Closed-Date:    Mon Jun 23 12:20:35 PDT 2003
>Last-Modified:  Mon Jun 23 12:20:35 PDT 2003
>Originator:     Stefan Esser
>Release:        FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:
System: FreeBSD StefanEsser.FreeBSD.org 5.0-CURRENT FreeBSD 5.0-CURRENT #1: Fri Jan 10 20:26:05 CET 2003 se@StefanEsser.FreeBSD.org:/usr/src/sys/i386/compile/ISDN686 i386
	
>Description:
The configure script for apache hung in the test for sem_open().
Truss revealed, that ksem_close() was being called in a tight loop.
The reason is a hard-coded return value of -1 in ksem_sem_close, which
becomes the result of ksem_close. Since this value is interpreted as
ERESTART on return from the system call, the call is repeated infinitely.
>How-To-Repeat:
cd /usr/ports/www/apache2
make configure
>Fix:
Apply the following patch:

Index: /sys/kern/uipc_sem.c
===================================================================
RCS file: /usr/cvs/src/sys/kern/uipc_sem.c,v
retrieving revision 1.3
diff -u -r1.3 uipc_sem.c
--- /sys/kern/uipc_sem.c	16 Oct 2002 10:42:13 -0000	1.3
+++ /sys/kern/uipc_sem.c	10 Jan 2003 19:25:51 -0000
@@ -592,7 +592,7 @@
 	if (ks != NULL && ks->ks_name != NULL)
 		error = sem_leave(td->td_proc, ks) == 0 ? 0 : EINVAL;
 	mtx_unlock(&sem_lock);
-	return (-1);
+	return (error);
 }
 
 #ifndef _SYS_SYSPROTO_H_
>Release-Note:
>Audit-Trail:
Responsible-Changed-From-To: gnats-admin->alfred 
Responsible-Changed-By: se 
Responsible-Changed-When: Fri Jan 10 14:09:11 PST 2003 
Responsible-Changed-Why:  
Assign my PR to original author of the affected function. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=46957 
State-Changed-From-To: open->closed 
State-Changed-By: alfred 
State-Changed-When: Mon Jun 23 12:19:34 PDT 2003 
State-Changed-Why:  
Fixed in rev 1.4 of uipc_sem.c.  Thank you. 

http://www.freebsd.org/cgi/query-pr.cgi?pr=46957 
>Unformatted:
 [Patch] Bogus return value (-1==ERESTART) of ksem_close() causes infinite loop.
 serious
 medium
 kern
 sw-bug
