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[PATCH 2/4] Adjust kernel-features.h for sendmmsg/recvmmsg

From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
To: libc-alpha at sourceware dot org
Date: Mon, 21 Mar 2016 17:41:05 -0300
Subject: [PATCH 2/4] Adjust kernel-features.h for sendmmsg/recvmmsg
Authentication-results: sourceware.org; auth=none
References: <1458592867-3057-1-git-send-email-adhemerval dot zanella at linaro dot org>
This patch cleanups the __ASSUME_RECVMMSG_* and __ASSUME_SENDMMSG_*
usage in linux recvmmsg and sendmmsg implementation.  It also fixes
a bug on i686/x86_64 when building with 2.6.32 kernel support.  The
changes in this patches are the following:

 * Remove the __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL for ports that
   for current minimum supported kernel already have direct recvmmsg
   syscall support (microblaze, powerpc, and spart).

 * Add __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL define for ports that
   still uses socketcall interface (i386, m68k, s390).

 * Remove the __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL for ports that
   for current minimum supported kernel alread have direct sendmmsg
   syscall support (powerpc, sparc).

 * Add __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL define for ports that
   still uses socketcall interface (i386, m68k, microblaze, and s390)

Along with the define changes, the linux recvmmsg and sendmmsg implementation
now uses a different strategy to use direct syscall, socketcall, runtime
socketcall (which issues a socketcall and update have_*), and stub function:

 1. If the architecture defines __ASSUME_{RECVMMSG,SENDMMSG}_SYSCALL the
    direct syscall is used instead.  This is the default behavior for most
    ports that do not support socketcall.

 2. Otherwise, if the architecture defines
    __ASSUME_{RECVMMSG,SENDMMSG}_SYSCALL_WITH_SOCKETCALL the socketcall
    interface will be used instead.  Different than the default
    __ASSUME_{RECVMMSG,SENDMMSG}_SOCKETCALL, this define is set per
    architecture.

 3. Otherwise, if the architecure define __ASSUME_SOCKETCALL the
    runtime socketcall call will be used which will test if the kernel
    supports {sendmmsg,recvmmsg} and set have_{recvmmsg,sendmmsg}
    accordingly.

 4. Otherwise the stub warning implementation will be use.

This approach also fixes the following i386/x86_64 issue:

 * For i686 with kernel 3.2.0 but with --enable-kernel=2.6.32 (minimum
   supported kernel) will use direct syscall where it should use runtime
   socketcall

 * For x86_64 with kernel 3.2.0 but with --enable-kernel=2.6.32 (minimum
   kernel) will use syscall where it should use stub.

Tested on i686, x86_64, aarch64, armhf, and powerpc64le.

	* sysdeps/unix/sysv/linux/i386/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Remove define.
	[__LINUX_KERNEL_VERSION > 0x030000]
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Add define.
	* sysdeps/unix/sysv/linux/m68k/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Remove define.
	* sysdeps/unix/sysv/linux/powerpc/kernel-features.h
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/s390/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Add define.
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/sh/kernel-features.h
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Remove define.
	* sysdeps/unix/sysv/linux/sparc/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/recvmmsg.c: Remove file.
	* sysdeps/unix/sysv/linux/mips/mips32/sendmmsg.c: Likewise.
	* sysdeps/unix/sysv/linux/recvmmsg.c (recvmmsg): Refactor
	__ASSUME macro usage.
	* sysdeps/unix/sysv/linux/sendmmsg.c (__sendmmsg): Likewise.
---
 ChangeLog                                          | 26 +++++++++++++++++++
 sysdeps/unix/sysv/linux/i386/kernel-features.h     |  8 ++++--
 sysdeps/unix/sysv/linux/m68k/kernel-features.h     |  2 ++
 .../unix/sysv/linux/microblaze/kernel-features.h   |  4 +--
 sysdeps/unix/sysv/linux/mips/mips32/recvmmsg.c     | 29 ----------------------
 sysdeps/unix/sysv/linux/mips/mips32/sendmmsg.c     | 29 ----------------------
 sysdeps/unix/sysv/linux/powerpc/kernel-features.h  |  3 ---
 sysdeps/unix/sysv/linux/recvmmsg.c                 | 26 +++++--------------
 sysdeps/unix/sysv/linux/s390/kernel-features.h     |  2 ++
 sysdeps/unix/sysv/linux/sendmmsg.c                 | 27 ++++++--------------
 sysdeps/unix/sysv/linux/sparc/kernel-features.h    |  6 -----
 11 files changed, 50 insertions(+), 112 deletions(-)
 delete mode 100644 sysdeps/unix/sysv/linux/mips/mips32/recvmmsg.c
 delete mode 100644 sysdeps/unix/sysv/linux/mips/mips32/sendmmsg.c

diff --git a/sysdeps/unix/sysv/linux/i386/kernel-features.h b/sysdeps/unix/sysv/linux/i386/kernel-features.h
index 148963c..3e25476 100644
--- a/sysdeps/unix/sysv/linux/i386/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/i386/kernel-features.h
@@ -21,10 +21,14 @@
 #define __ASSUME_SOCKETCALL		1
 
 /* The recvmmsg syscall was added for i386 in 2.6.33.  */
-#define __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL	1
+#if __LINUX_KERNEL_VERSION >= 0x020621
+# define __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL	1
+#endif
 
 /* The sendmmsg syscall was added for i386 in 3.0.  */
-#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
+#if __LINUX_KERNEL_VERSION >= 0x030000
+# define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
+#endif
 
 /* Direct socketcalls available with kernel 4.3.  */
 #if __LINUX_KERNEL_VERSION >= 0x040300
diff --git a/sysdeps/unix/sysv/linux/m68k/kernel-features.h b/sysdeps/unix/sysv/linux/m68k/kernel-features.h
index dec04f0..0945779 100644
--- a/sysdeps/unix/sysv/linux/m68k/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/m68k/kernel-features.h
@@ -19,6 +19,8 @@
 
 /* m68k uses socketcall.  */
 #define __ASSUME_SOCKETCALL	1
+#define __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL	1
+#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
 
 /* Direct socketcalls available with kernel 4.3.  */
 #if __LINUX_KERNEL_VERSION >= 0x040300
diff --git a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
index db471ef..e25b6ed 100644
--- a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
@@ -18,6 +18,7 @@
 
 /* MicroBlaze uses socketcall.  */
 #define __ASSUME_SOCKETCALL	1
+#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
 
 /* All supported kernel versions for MicroBlaze have these syscalls.  */
 #define __ASSUME_SOCKET_SYSCALL		1
@@ -36,9 +37,6 @@
 #define __ASSUME_GETSOCKOPT_SYSCALL	1
 #define __ASSUME_SETSOCKOPT_SYSCALL	1
 
-/* Support for the accept4 and recvmmsg syscalls was added in 2.6.33.  */
-#define __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL      1
-
 /* Support for the futimesat syscall was added in 2.6.33.  */
 #define __ASSUME_FUTIMESAT              1
 
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/recvmmsg.c b/sysdeps/unix/sysv/linux/mips/mips32/recvmmsg.c
deleted file mode 100644
index c2a3440..0000000
--- a/sysdeps/unix/sysv/linux/mips/mips32/recvmmsg.c
+++ /dev/null
@@ -1,29 +0,0 @@
-/* Copyright (C) 2010-2016 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <http://www.gnu.org/licenses/>.  */
-
-/* Avoid recvmmsg.c trying to use a definition based on the socketcall
-   syscall and internal_recvmmsg.S.  */
-
-#include <errno.h>
-#include <sys/socket.h>
-
-#include <sysdep-cancel.h>
-#include <sys/syscall.h>
-
-#undef __NR_socketcall
-
-#include <sysdeps/unix/sysv/linux/recvmmsg.c>
diff --git a/sysdeps/unix/sysv/linux/mips/mips32/sendmmsg.c b/sysdeps/unix/sysv/linux/mips/mips32/sendmmsg.c
deleted file mode 100644
index 7cd4e15..0000000
--- a/sysdeps/unix/sysv/linux/mips/mips32/sendmmsg.c
+++ /dev/null
@@ -1,29 +0,0 @@
-/* Copyright (C) 2011-2016 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <http://www.gnu.org/licenses/>.  */
-
-/* Avoid sendmmsg.c trying to use a definition based on the socketcall
-   syscall and internal_sendmmsg.S.  */
-
-#include <errno.h>
-#include <sys/socket.h>
-
-#include <sysdep-cancel.h>
-#include <sys/syscall.h>
-
-#undef __NR_socketcall
-
-#include <sysdeps/unix/sysv/linux/sendmmsg.c>
diff --git a/sysdeps/unix/sysv/linux/powerpc/kernel-features.h b/sysdeps/unix/sysv/linux/powerpc/kernel-features.h
index 5449f18..825c0f0 100644
--- a/sysdeps/unix/sysv/linux/powerpc/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/powerpc/kernel-features.h
@@ -37,7 +37,4 @@
 #define __ASSUME_GETSOCKOPT_SYSCALL	1
 #define __ASSUME_SETSOCKOPT_SYSCALL	1
 
-/* The sendmmsg syscall was added for PowerPC in 3.0.  */
-#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
-
 #include_next <kernel-features.h>
diff --git a/sysdeps/unix/sysv/linux/recvmmsg.c b/sysdeps/unix/sysv/linux/recvmmsg.c
index bf18260..fb3f325 100644
--- a/sysdeps/unix/sysv/linux/recvmmsg.c
+++ b/sysdeps/unix/sysv/linux/recvmmsg.c
@@ -16,39 +16,26 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
 #include <sys/socket.h>
-
 #include <sysdep-cancel.h>
-#include <sys/syscall.h>
-#include <kernel-features.h>
-
-/* Do not use the recvmmsg syscall on socketcall architectures unless
-   it was added at the same time as the socketcall support or can be
-   assumed to be present.  */
-#if defined __ASSUME_SOCKETCALL \
-    && !defined __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL \
-    && !defined __ASSUME_RECVMMSG_SYSCALL
-# undef __NR_recvmmsg
-#endif
+#include <socketcall.h>
+#include <shlib-compat.h>
 
-#ifdef __NR_recvmmsg
+#ifdef __ASSUME_RECVMMSG_SYSCALL
 int
 recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
 	  struct timespec *tmo)
 {
   return SYSCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
 }
-#elif defined __NR_socketcall
-# include <socketcall.h>
-# ifdef __ASSUME_RECVMMSG_SOCKETCALL
+#elif defined __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL
 int
 recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
 	  struct timespec *tmo)
 {
   return SOCKETCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
 }
-# else
+#elif defined __ASSUME_SOCKETCALL
 static int have_recvmmsg;
 
 int
@@ -87,7 +74,6 @@ recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
   __set_errno (ENOSYS);
   return -1;
 }
-# endif /* __ASSUME_RECVMMSG_SOCKETCALL  */
-#else
+#else /* __ASSUME_RECVMMSG_SOCKETCALL  */
 # include <socket/recvmmsg.c>
 #endif
diff --git a/sysdeps/unix/sysv/linux/s390/kernel-features.h b/sysdeps/unix/sysv/linux/s390/kernel-features.h
index b3edee4..4656c4a 100644
--- a/sysdeps/unix/sysv/linux/s390/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/s390/kernel-features.h
@@ -19,6 +19,8 @@
 
 /* S/390 uses socketcall.  */
 #define __ASSUME_SOCKETCALL		1
+#define __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL	1
+#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
 
 /* Direct socketcalls available with kernel 4.3.  */
 #if __LINUX_KERNEL_VERSION >= 0x040300
diff --git a/sysdeps/unix/sysv/linux/sendmmsg.c b/sysdeps/unix/sysv/linux/sendmmsg.c
index 6e0d46b..37f0ec9 100644
--- a/sysdeps/unix/sysv/linux/sendmmsg.c
+++ b/sysdeps/unix/sysv/linux/sendmmsg.c
@@ -16,23 +16,11 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
 #include <sys/socket.h>
-
 #include <sysdep-cancel.h>
-#include <sys/syscall.h>
-#include <kernel-features.h>
-
-/* Do not use the sendmmsg syscall on socketcall architectures unless
-   it was added at the same time as the socketcall support or can be
-   assumed to be present.  */
-#if defined __ASSUME_SOCKETCALL \
-    && !defined __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL \
-    && !defined __ASSUME_SENDMMSG_SYSCALL
-# undef __NR_sendmmsg
-#endif
+#include <socketcall.h>
 
-#ifdef __NR_sendmmsg
+#ifdef __ASSUME_SENDMMSG_SYSCALL
 int
 __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
 {
@@ -40,15 +28,15 @@ __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
 }
 libc_hidden_def (__sendmmsg)
 weak_alias (__sendmmsg, sendmmsg)
-#elif defined __NR_socketcall
-# include <socketcall.h>
-# ifdef __ASSUME_SENDMMSG_SOCKETCALL
+#elif defined __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL
 int
 __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
 {
   return SOCKETCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
 }
-# else
+libc_hidden_def (__sendmmsg)
+weak_alias (__sendmmsg, sendmmsg)
+#elif defined __ASSUME_SOCKETCALL
 static int have_sendmmsg;
 
 int
@@ -85,9 +73,8 @@ __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
   __set_errno (ENOSYS);
   return -1;
 }
-# endif /* __ASSUME_SENDMMSG_SOCKETCALL  */
 libc_hidden_def (__sendmmsg)
 weak_alias (__sendmmsg, sendmmsg)
-#else
+#else /* __ASSUME_SENDMMSG_SOCKETCALL  */
 # include <socket/sendmmsg.c>
 #endif
diff --git a/sysdeps/unix/sysv/linux/sparc/kernel-features.h b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
index 386f230..486036d 100644
--- a/sysdeps/unix/sysv/linux/sparc/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
@@ -23,12 +23,6 @@
 /* The accept4 syscall was added for SPARC in 2.6.28.  */
 #define __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL	1
 
-/* The recvmmsg syscall was added for SPARC in 2.6.33.  */
-#define __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL	1
-
-/* The sendmmsg syscall was added for SPARC in 3.0.  */
-#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
-
 #include_next <kernel-features.h>
 
 /* 32-bit SPARC kernels do not support
-- 
1.9.1
Follow-Ups:
- Re: [PATCH 2/4] Adjust kernel-features.h for sendmmsg/recvmmsg
  - From: Joseph Myers
References:
- [PATCH 0/4] Fix {recv,send}{m}msg standard compliance (BZ#16919)
  - From: Adhemerval Zanella
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