diff mbox

Simplify accept4, recvmmsg, sendmmsg code

Message ID alpine.DEB.2.20.1705092045350.28688@digraph.polyomino.org.uk
State New, archived
Headers show

Commit Message

Joseph Myers May 9, 2017, 8:46 p.m. UTC
The accept4, recvmmsg and sendmmsg functions had macros
__ASSUME_*_SYSCALL_WITH_SOCKETCALL.  Before we could assume kernels
with the relevant functionality, these macros represented the
conditions under which, on a socketcall architecture, glibc could just
call the syscall unconditionally and not have to deal with socketcall
at all for those functions, because if the syscall didn't work for
them the socketcall call wouldn't either.

Now we can assume kernels with the relevant functionality, the only
question is whether we can assume the syscall is present; if not, we
are on a socketcall architecture and just use socketcall instead.
Thus, this patch removes the macros that are no longer necessary, and
simplifies the code for accept4, recvmmsg and sendmmsg to use the same
logic as the other C implementations of socket functions that may use
a syscall or socketcall depending on kernel support.

Tested for x86_64 and x86.

2017-05-09  Joseph Myers  <joseph@codesourcery.com>

	* sysdeps/unix/sysv/linux/accept4.c (accept4): Use syscall if
	[__ASSUME_ACCEPT4_SYSCALL], otherwise socketcall.
	* sysdeps/unix/sysv/linux/recvmmsg.c (recvmmsg): Use syscall if
	[__ASSUME_RECVMMSG_SYSCALL], otherwise socketcall.
	* sysdeps/unix/sysv/linux/sendmmsg.c (__sendmmsg): Use syscall if
	[__ASSUME_SENDMMSG_SYSCALL], otherwise socketcall.
	* sysdeps/unix/sysv/linux/kernel-features.h
	(__ASSUME_ACCEPT4_SYSCALL): Move to general list of macros for
	socket syscalls.
	(__ASSUME_RECVMMSG_SYSCALL): Likewise.
	(__ASSUME_SENDMMSG_SYSCALL): Likewise.
	* sysdeps/unix/sysv/linux/i386/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Remove.
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Remove.
	* sysdeps/unix/sysv/linux/powerpc/kernel-features.h
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/sh/kernel-features.h
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	* sysdeps/unix/sysv/linux/sparc/kernel-features.h
	(__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL): Likewise.
	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.

Comments

Adhemerval Zanella May 9, 2017, 9:37 p.m. UTC | #1
On 09/05/2017 17:46, Joseph Myers wrote:
> The accept4, recvmmsg and sendmmsg functions had macros
> __ASSUME_*_SYSCALL_WITH_SOCKETCALL.  Before we could assume kernels
> with the relevant functionality, these macros represented the
> conditions under which, on a socketcall architecture, glibc could just
> call the syscall unconditionally and not have to deal with socketcall
> at all for those functions, because if the syscall didn't work for
> them the socketcall call wouldn't either.
> 
> Now we can assume kernels with the relevant functionality, the only
> question is whether we can assume the syscall is present; if not, we
> are on a socketcall architecture and just use socketcall instead.
> Thus, this patch removes the macros that are no longer necessary, and
> simplifies the code for accept4, recvmmsg and sendmmsg to use the same
> logic as the other C implementations of socket functions that may use
> a syscall or socketcall depending on kernel support.
> 
> Tested for x86_64 and x86.

I think we can also now remove mips sendmmsg and recvmmsg implementations
(it does not define __ASSUME_SOCKETCALL, so it should use wire-up calls
as well).

> 
> 2017-05-09  Joseph Myers  <joseph@codesourcery.com>
> 
> 	* sysdeps/unix/sysv/linux/accept4.c (accept4): Use syscall if
> 	[__ASSUME_ACCEPT4_SYSCALL], otherwise socketcall.
> 	* sysdeps/unix/sysv/linux/recvmmsg.c (recvmmsg): Use syscall if
> 	[__ASSUME_RECVMMSG_SYSCALL], otherwise socketcall.
> 	* sysdeps/unix/sysv/linux/sendmmsg.c (__sendmmsg): Use syscall if
> 	[__ASSUME_SENDMMSG_SYSCALL], otherwise socketcall.
> 	* sysdeps/unix/sysv/linux/kernel-features.h
> 	(__ASSUME_ACCEPT4_SYSCALL): Move to general list of macros for
> 	socket syscalls.
> 	(__ASSUME_RECVMMSG_SYSCALL): Likewise.
> 	(__ASSUME_SENDMMSG_SYSCALL): Likewise.
> 	* sysdeps/unix/sysv/linux/i386/kernel-features.h
> 	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Remove.
> 	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
> 	* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
> 	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Remove.
> 	* sysdeps/unix/sysv/linux/powerpc/kernel-features.h
> 	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
> 	* sysdeps/unix/sysv/linux/sh/kernel-features.h
> 	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
> 	* sysdeps/unix/sysv/linux/sparc/kernel-features.h
> 	(__ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL): Likewise.
> 	(__ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.
> 	(__ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL): Likewise.

LGTM with some one comment remark.

> diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
> index 7728565..76053b5 100644
> --- a/sysdeps/unix/sysv/linux/kernel-features.h
> +++ b/sysdeps/unix/sysv/linux/kernel-features.h
> @@ -71,16 +71,6 @@
>     2.6.27.  */
>  #define __ASSUME_IN_NONBLOCK	1
>  
> -/* Support for accept4 functionality was added in 2.6.28, but for some
> -   architectures using a separate syscall rather than socketcall that
> -   syscall was only added later, and some architectures first had
> -   socketcall support then a separate syscall.  Define
> -   __ASSUME_ACCEPT4_SYSCALL if it is available through a separate
> -   syscall, and __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL if it became
> -   available through a separate syscall at the same time as through
> -   socketcall.  */
> -#define __ASSUME_ACCEPT4_SYSCALL	1
> -
>  /* Support for the FUTEX_CLOCK_REALTIME flag was added in 2.6.29.  */
>  #define __ASSUME_FUTEX_CLOCK_REALTIME	1
>  
> @@ -88,18 +78,12 @@
>  #define __ASSUME_PREADV	1
>  #define __ASSUME_PWRITEV	1
>  
> -/* Support for recvmmsg functionality was added in 2.6.33.  The macros
> -   defined correspond to those for accept4.  */
> -#define __ASSUME_RECVMMSG_SYSCALL	1
> -
>  /* statfs fills in f_flags since 2.6.36.  */
>  #if __LINUX_KERNEL_VERSION >= 0x020624
>  # define __ASSUME_STATFS_F_FLAGS	1
>  #endif
>  
> -/* Support for sendmmsg functionality was added in 3.0.  The macros
> -   defined correspond to those for accept4 and recvmmsg.  */
> -#define __ASSUME_SENDMMSG_SYSCALL	1
> +/* Support for sendmmsg functionality was added in 3.0.  */
>  #define __ASSUME_SENDMMSG	1

Since you are there, wouldn't be better to add a comment that we
kept __ASSUME_SENDMMSG because of resolv code instead of kernel
support?
Joseph Myers May 9, 2017, 9:44 p.m. UTC | #2
On Tue, 9 May 2017, Adhemerval Zanella wrote:

> > -/* Support for sendmmsg functionality was added in 3.0.  The macros
> > -   defined correspond to those for accept4 and recvmmsg.  */
> > -#define __ASSUME_SENDMMSG_SYSCALL	1
> > +/* Support for sendmmsg functionality was added in 3.0.  */
> >  #define __ASSUME_SENDMMSG	1
> 
> Since you are there, wouldn't be better to add a comment that we
> kept __ASSUME_SENDMMSG because of resolv code instead of kernel
> support?

That's not what we do for __ASSUME_SENDFILE, __ASSUME_ATFCTS etc. (other 
macros for features present for ports using the Linux kernel but not 
necessarily for other ports).
diff mbox

Patch

diff --git a/sysdeps/unix/sysv/linux/accept4.c b/sysdeps/unix/sysv/linux/accept4.c
index 0592f43..1590c02 100644
--- a/sysdeps/unix/sysv/linux/accept4.c
+++ b/sysdeps/unix/sysv/linux/accept4.c
@@ -28,14 +28,9 @@ 
 int
 accept4 (int fd, __SOCKADDR_ARG addr, socklen_t *addr_len, int flags)
 {
-/* Do not use the accept4 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_ACCEPT4_SYSCALL_WITH_SOCKETCALL \
-    && !defined __ASSUME_ACCEPT4_SYSCALL
-  return SOCKETCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
-#else
+#ifdef __ASSUME_ACCEPT4_SYSCALL
   return SYSCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
+#else
+  return SOCKETCALL_CANCEL (accept4, fd, addr.__sockaddr__, addr_len, flags);
 #endif
 }
diff --git a/sysdeps/unix/sysv/linux/i386/kernel-features.h b/sysdeps/unix/sysv/linux/i386/kernel-features.h
index 96a8e3b..c6eb20f 100644
--- a/sysdeps/unix/sysv/linux/i386/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/i386/kernel-features.h
@@ -20,12 +20,6 @@ 
 /* i386 uses socketcall.  */
 #define __ASSUME_SOCKETCALL		1
 
-/* The recvmmsg syscall was added for i386 in 2.6.33.  */
-#define __ASSUME_RECVMMSG_SYSCALL_WITH_SOCKETCALL	1
-
-/* The sendmmsg syscall was added for i386 in 3.0.  */
-#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
-
 /* Direct socketcalls available with kernel 4.3.  */
 #if __LINUX_KERNEL_VERSION >= 0x040300
 # define __ASSUME_SOCKET_SYSCALL             1
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h
index 7728565..76053b5 100644
--- a/sysdeps/unix/sysv/linux/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/kernel-features.h
@@ -71,16 +71,6 @@ 
    2.6.27.  */
 #define __ASSUME_IN_NONBLOCK	1
 
-/* Support for accept4 functionality was added in 2.6.28, but for some
-   architectures using a separate syscall rather than socketcall that
-   syscall was only added later, and some architectures first had
-   socketcall support then a separate syscall.  Define
-   __ASSUME_ACCEPT4_SYSCALL if it is available through a separate
-   syscall, and __ASSUME_ACCEPT4_SYSCALL_WITH_SOCKETCALL if it became
-   available through a separate syscall at the same time as through
-   socketcall.  */
-#define __ASSUME_ACCEPT4_SYSCALL	1
-
 /* Support for the FUTEX_CLOCK_REALTIME flag was added in 2.6.29.  */
 #define __ASSUME_FUTEX_CLOCK_REALTIME	1
 
@@ -88,18 +78,12 @@ 
 #define __ASSUME_PREADV	1
 #define __ASSUME_PWRITEV	1
 
-/* Support for recvmmsg functionality was added in 2.6.33.  The macros
-   defined correspond to those for accept4.  */
-#define __ASSUME_RECVMMSG_SYSCALL	1
-
 /* statfs fills in f_flags since 2.6.36.  */
 #if __LINUX_KERNEL_VERSION >= 0x020624
 # define __ASSUME_STATFS_F_FLAGS	1
 #endif
 
-/* Support for sendmmsg functionality was added in 3.0.  The macros
-   defined correspond to those for accept4 and recvmmsg.  */
-#define __ASSUME_SENDMMSG_SYSCALL	1
+/* Support for sendmmsg functionality was added in 3.0.  */
 #define __ASSUME_SENDMMSG	1
 
 /* On most architectures, most socket syscalls are supported for all
@@ -111,6 +95,9 @@ 
 #define __ASSUME_CONNECT_SYSCALL	1
 #define __ASSUME_RECVFROM_SYSCALL	1
 #define __ASSUME_SENDTO_SYSCALL		1
+#define __ASSUME_ACCEPT4_SYSCALL	1
+#define __ASSUME_RECVMMSG_SYSCALL	1
+#define __ASSUME_SENDMMSG_SYSCALL	1
 
 /* Support for SysV IPC through wired syscalls.  All supported architectures
    either support ipc syscall and/or all the ipc correspondent syscalls.  */
diff --git a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
index fe170a0..0257524 100644
--- a/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/microblaze/kernel-features.h
@@ -33,9 +33,6 @@ 
 #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
-
 #include_next <kernel-features.h>
 
 /* Support for the pselect6, preadv and pwritev syscalls was added in
diff --git a/sysdeps/unix/sysv/linux/powerpc/kernel-features.h b/sysdeps/unix/sysv/linux/powerpc/kernel-features.h
index dc9ad94..e026394 100644
--- a/sysdeps/unix/sysv/linux/powerpc/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/powerpc/kernel-features.h
@@ -34,9 +34,6 @@ 
 #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
-
 /* Define this if your 32-bit syscall API requires 64-bit register
    pairs to start with an even-number register.  */
 #ifndef __powerpc64__
diff --git a/sysdeps/unix/sysv/linux/recvmmsg.c b/sysdeps/unix/sysv/linux/recvmmsg.c
index de44129..60e06b7 100644
--- a/sysdeps/unix/sysv/linux/recvmmsg.c
+++ b/sysdeps/unix/sysv/linux/recvmmsg.c
@@ -28,14 +28,9 @@  int
 recvmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags,
 	  struct timespec *tmo)
 {
-  /* 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
-  return SOCKETCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
-#else
+#ifdef __ASSUME_RECVMMSG_SYSCALL
   return SYSCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
+#else
+  return SOCKETCALL_CANCEL (recvmmsg, fd, vmessages, vlen, flags, tmo);
 #endif
 }
diff --git a/sysdeps/unix/sysv/linux/sendmmsg.c b/sysdeps/unix/sysv/linux/sendmmsg.c
index c559623..e0c2556 100644
--- a/sysdeps/unix/sysv/linux/sendmmsg.c
+++ b/sysdeps/unix/sysv/linux/sendmmsg.c
@@ -27,15 +27,10 @@ 
 int
 __sendmmsg (int fd, struct mmsghdr *vmessages, unsigned int vlen, int flags)
 {
-  /* 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
-  return SOCKETCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
-#else
+#ifdef __ASSUME_SENDMMSG_SYSCALL
   return SYSCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
+#else
+  return SOCKETCALL_CANCEL (sendmmsg, fd, vmessages, vlen, flags);
 #endif
 }
 libc_hidden_def (__sendmmsg)
diff --git a/sysdeps/unix/sysv/linux/sh/kernel-features.h b/sysdeps/unix/sysv/linux/sh/kernel-features.h
index b0b3215..175b4f5 100644
--- a/sysdeps/unix/sysv/linux/sh/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/sh/kernel-features.h
@@ -37,9 +37,6 @@ 
 #define __ASSUME_GETSOCKOPT_SYSCALL	1
 #define __ASSUME_SETSOCKOPT_SYSCALL	1
 
-/* The sendmmsg syscall was added for SH in 3.0.  */
-#define __ASSUME_SENDMMSG_SYSCALL_WITH_SOCKETCALL	1
-
 #include_next <kernel-features.h>
 
 /* SH does not have a 64-bit inode field.  */
diff --git a/sysdeps/unix/sysv/linux/sparc/kernel-features.h b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
index c833201..72065a0 100644
--- a/sysdeps/unix/sysv/linux/sparc/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/sparc/kernel-features.h
@@ -20,15 +20,6 @@ 
 /* SPARC uses socketcall.  */
 #define __ASSUME_SOCKETCALL		1
 
-/* 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