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Date:      Sun, 19 Apr 2009 13:48:43 +0000 (UTC)
From:      Dmitry Chagin <dchagin@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r191269 - head/sys/compat/linux
Message-ID:  <200904191348.n3JDmhVH010871@svn.freebsd.org>
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Author: dchagin
Date: Sun Apr 19 13:48:42 2009
New Revision: 191269
URL: http://svn.freebsd.org/changeset/base/191269

Log:
  Remove support for FUTEX_REQUEUE operation.
  Glibc does not use this operation since 2.3.3 version (Jun 2004),
  as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
  Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
  FUTEX_REQUEUE returned EINVAL.
  
  Any application directly using FUTEX_REQUEUE without return
  value checking are definitely broken.
  
  Limit quantity of messages per process about unsupported
  operation.
  
  Approved by:	kib (mentor)
  MFC after:	1 month

Modified:
  head/sys/compat/linux/linux_emul.c
  head/sys/compat/linux/linux_emul.h
  head/sys/compat/linux/linux_futex.c

Modified: head/sys/compat/linux/linux_emul.c
==============================================================================
--- head/sys/compat/linux/linux_emul.c	Sun Apr 19 12:41:37 2009	(r191268)
+++ head/sys/compat/linux/linux_emul.c	Sun Apr 19 13:48:42 2009	(r191269)
@@ -86,6 +86,7 @@ linux_proc_init(struct thread *td, pid_t
 		em = malloc(sizeof *em, M_LINUX, M_WAITOK | M_ZERO);
 		em->pid = child;
 		em->pdeath_signal = 0;
+		em->used_requeue = 0;
 		em->robust_futexes = NULL;
 		if (flags & LINUX_CLONE_THREAD) {
 			/* handled later in the code */

Modified: head/sys/compat/linux/linux_emul.h
==============================================================================
--- head/sys/compat/linux/linux_emul.h	Sun Apr 19 12:41:37 2009	(r191268)
+++ head/sys/compat/linux/linux_emul.h	Sun Apr 19 13:48:42 2009	(r191269)
@@ -51,6 +51,7 @@ struct linux_emuldata {
 	struct linux_emuldata_shared *shared;
 
 	int	pdeath_signal;		/* parent death signal */
+	int	used_requeue;		/* uses deprecated futex op */
 
 	struct	linux_robust_list_head	*robust_futexes;
 

Modified: head/sys/compat/linux/linux_futex.c
==============================================================================
--- head/sys/compat/linux/linux_futex.c	Sun Apr 19 12:41:37 2009	(r191268)
+++ head/sys/compat/linux/linux_futex.c	Sun Apr 19 13:48:42 2009	(r191269)
@@ -114,6 +114,7 @@ linux_sys_futex(struct thread *td, struc
 	struct timeval tv = {0, 0};
 	struct futex *f2;
 	int op_ret;
+	struct linux_emuldata *em;
 
 #ifdef	DEBUG
 	if (ldebug(sys_futex))
@@ -262,19 +263,6 @@ linux_sys_futex(struct thread *td, struc
 		FUTEX_SYSTEM_UNLOCK;
 		break;
 
-	case LINUX_FUTEX_REQUEUE:
-		FUTEX_SYSTEM_LOCK;
-
-		f = futex_get(args->uaddr, FUTEX_UNLOCKED);
-		newf = futex_get(args->uaddr2, FUTEX_UNLOCKED);
-		td->td_retval[0] = futex_wake(f, args->val, newf,
-		    (int)(unsigned long)args->timeout);
-		futex_put(f);
-		futex_put(newf);
-
-		FUTEX_SYSTEM_UNLOCK;
-		break;
-
 	case LINUX_FUTEX_WAKE_OP:
 		FUTEX_SYSTEM_LOCK;
 #ifdef DEBUG
@@ -342,6 +330,23 @@ linux_sys_futex(struct thread *td, struc
 		/* not yet implemented */
 		return (ENOSYS);
 
+	case LINUX_FUTEX_REQUEUE:
+
+		/*
+		 * Glibc does not use this operation since Jun 2004 (2.3.3),
+		 * as it is racy and replaced by FUTEX_CMP_REQUEUE operation.
+		 * Glibc versions prior to 2.3.3 fall back to FUTEX_WAKE when
+		 * FUTEX_REQUEUE returned EINVAL.
+		 */
+		em = em_find(td->td_proc, EMUL_DONTLOCK);
+		if (em->used_requeue == 0) {
+			printf("linux(%s (%d)) sys_futex: "
+			    "unsupported futex_requeue op\n",
+			    td->td_proc->p_comm, td->td_proc->p_pid);
+			em->used_requeue = 1;
+		}
+		return (EINVAL);
+
 	default:
 		printf("linux_sys_futex: unknown op %d\n",
 		    args->op);

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