From: Philippe Troin <phil@fifi.org>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Albert Cahalan <albert@users.sourceforge.net>,
linux-kernel mailing list <linux-kernel@vger.kernel.org>,
Andrew Morton OSDL <akpm@osdl.org>
Subject: Re: errno
Date: 05 May 2004 18:16:15 -0700 [thread overview]
Message-ID: <87smeejqxs.fsf@ceramic.fifi.org> (raw)
In-Reply-To: <87r7u0g2cf.fsf@electrolyt.fifi.org>
Philippe Troin <phil@fifi.org> writes:
> Linus Torvalds <torvalds@osdl.org> writes:
>
> > On Mon, 3 May 2004, Albert Cahalan wrote:
> > >
> > > The obvious fix would be to stuff errno into the
> > > task_struct, hmmm?
> >
> > No. "errno" is one of those fundamentally broken things that should not
> > exist. It was wrogn in original UNIX, it's wrong now.
> >
> > The kernel usage comes not from the kernel wanting to use it per se (the
> > kernel has always used the "negative error" approach), but from some
> > misguided kernel modules using the user-space interfaces.
> >
> > The Linux way of returning negative error numbers is much nicer. It's
> > inherently thread-safe, and it has no performance downsides. Of course, it
> > does depend on having enough of a result domain that you can always
> > separate error returns from good returns, but that's true in practice for
> > all system calls.
>
> Except of course for fcntl(fd, F_GETOWN) where the owner is a
> (negative) process group... If the owning process group has a "low
> enough" PGID, it collides with errors and glibc reports an error and
> sets errno to -PGID. One might argue that in this instance, that the
> BSD's overloading of the pid field with pgids is at fault, but the bug
> still remains :-)
This is a patch against 2.6.5 for what I am talking about. Of course,
glibc needs to be patched as well to transparently issue a
F_GETOWN_ARG when the user requests F_GETOWN...
Phil.
diff -rcN linux-2.6.5.orig/fs/fcntl.c linux-2.6.5/fs/fcntl.c
*** linux-2.6.5.orig/fs/fcntl.c Sat Apr 3 19:37:36 2004
--- linux-2.6.5/fs/fcntl.c Wed May 5 18:06:02 2004
***************
*** 323,328 ****
--- 323,339 ----
err = filp->f_owner.pid;
force_successful_syscall_return();
break;
+ case F_GETOWN_ARG:
+ /*
+ * Works around F_GETOWN's return limitations.
+ * Libc will transparently convert F_GETOWN to
+ * F_GETOWN_ARG.
+ */
+ err = 0;
+ if (copy_to_user(&filp->f_owner.pid, (void*)arg,
+ sizeof(filp->f_owner.pid)))
+ err = -EFAULT;
+ break;
case F_SETOWN:
err = f_setown(filp, arg, 1);
break;
diff -rcN linux-2.6.5.orig/include/asm-alpha/fcntl.h linux-2.6.5/include/asm-alpha/fcntl.h
*** linux-2.6.5.orig/include/asm-alpha/fcntl.h Sat Apr 3 19:37:24 2004
--- linux-2.6.5/include/asm-alpha/fcntl.h Wed May 5 17:57:03 2004
***************
*** 36,41 ****
--- 36,43 ----
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
+ #define F_GETOWN_ARG 12 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-arm/fcntl.h linux-2.6.5/include/asm-arm/fcntl.h
*** linux-2.6.5.orig/include/asm-arm/fcntl.h Sat Apr 3 19:36:27 2004
--- linux-2.6.5/include/asm-arm/fcntl.h Wed May 5 17:56:51 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-arm26/fcntl.h linux-2.6.5/include/asm-arm26/fcntl.h
*** linux-2.6.5.orig/include/asm-arm26/fcntl.h Sat Apr 3 19:37:40 2004
--- linux-2.6.5/include/asm-arm26/fcntl.h Wed May 5 17:56:47 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-cris/fcntl.h linux-2.6.5/include/asm-cris/fcntl.h
*** linux-2.6.5.orig/include/asm-cris/fcntl.h Sat Apr 3 19:36:25 2004
--- linux-2.6.5/include/asm-cris/fcntl.h Wed May 5 17:56:41 2004
***************
*** 41,46 ****
--- 41,48 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-h8300/fcntl.h linux-2.6.5/include/asm-h8300/fcntl.h
*** linux-2.6.5.orig/include/asm-h8300/fcntl.h Sat Apr 3 19:37:43 2004
--- linux-2.6.5/include/asm-h8300/fcntl.h Wed May 5 17:56:37 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-i386/fcntl.h linux-2.6.5/include/asm-i386/fcntl.h
*** linux-2.6.5.orig/include/asm-i386/fcntl.h Sat Apr 3 19:37:23 2004
--- linux-2.6.5/include/asm-i386/fcntl.h Wed May 5 17:56:21 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-ia64/fcntl.h linux-2.6.5/include/asm-ia64/fcntl.h
*** linux-2.6.5.orig/include/asm-ia64/fcntl.h Sat Apr 3 19:37:23 2004
--- linux-2.6.5/include/asm-ia64/fcntl.h Wed May 5 17:56:11 2004
***************
*** 43,48 ****
--- 43,50 ----
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
+ #define F_GETOWN_ARG 12 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-m68k/fcntl.h linux-2.6.5/include/asm-m68k/fcntl.h
*** linux-2.6.5.orig/include/asm-m68k/fcntl.h Sat Apr 3 19:36:53 2004
--- linux-2.6.5/include/asm-m68k/fcntl.h Wed May 5 17:55:57 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-mips/fcntl.h linux-2.6.5/include/asm-mips/fcntl.h
*** linux-2.6.5.orig/include/asm-mips/fcntl.h Sat Apr 3 19:37:43 2004
--- linux-2.6.5/include/asm-mips/fcntl.h Wed May 5 17:55:36 2004
***************
*** 42,47 ****
--- 42,48 ----
#define F_GETOWN 23 /* for sockets. */
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
+ #define F_GETOWN_ARG 25 /* same as F_GETOWN, but uses arg */
#ifndef __mips64
#define F_GETLK64 33 /* using 'struct flock64' */
diff -rcN linux-2.6.5.orig/include/asm-parisc/fcntl.h linux-2.6.5/include/asm-parisc/fcntl.h
*** linux-2.6.5.orig/include/asm-parisc/fcntl.h Sat Apr 3 19:37:07 2004
--- linux-2.6.5/include/asm-parisc/fcntl.h Wed May 5 17:55:10 2004
***************
*** 42,47 ****
--- 42,48 ----
#define F_SETOWN 12 /* for sockets. */
#define F_SETSIG 13 /* for sockets. */
#define F_GETSIG 14 /* for sockets. */
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-ppc/fcntl.h linux-2.6.5/include/asm-ppc/fcntl.h
*** linux-2.6.5.orig/include/asm-ppc/fcntl.h Sat Apr 3 19:37:07 2004
--- linux-2.6.5/include/asm-ppc/fcntl.h Wed May 5 17:54:59 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-ppc64/fcntl.h linux-2.6.5/include/asm-ppc64/fcntl.h
*** linux-2.6.5.orig/include/asm-ppc64/fcntl.h Sat Apr 3 19:36:15 2004
--- linux-2.6.5/include/asm-ppc64/fcntl.h Wed May 5 17:54:51 2004
***************
*** 42,47 ****
--- 42,49 ----
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
+ #define F_GETOWN_ARG 12 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-s390/fcntl.h linux-2.6.5/include/asm-s390/fcntl.h
*** linux-2.6.5.orig/include/asm-s390/fcntl.h Sat Apr 3 19:36:12 2004
--- linux-2.6.5/include/asm-s390/fcntl.h Wed May 5 17:54:43 2004
***************
*** 48,53 ****
--- 48,55 ----
#define F_SETLKW64 14
#endif /* ! __s390x__ */
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-sh/fcntl.h linux-2.6.5/include/asm-sh/fcntl.h
*** linux-2.6.5.orig/include/asm-sh/fcntl.h Sat Apr 3 19:37:42 2004
--- linux-2.6.5/include/asm-sh/fcntl.h Wed May 5 17:54:29 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-sparc/fcntl.h linux-2.6.5/include/asm-sparc/fcntl.h
*** linux-2.6.5.orig/include/asm-sparc/fcntl.h Sat Apr 3 19:38:20 2004
--- linux-2.6.5/include/asm-sparc/fcntl.h Wed May 5 17:54:23 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-sparc64/fcntl.h linux-2.6.5/include/asm-sparc64/fcntl.h
*** linux-2.6.5.orig/include/asm-sparc64/fcntl.h Sat Apr 3 19:38:20 2004
--- linux-2.6.5/include/asm-sparc64/fcntl.h Wed May 5 17:54:18 2004
***************
*** 35,40 ****
--- 35,41 ----
#define F_SETLKW 9
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
+ #define F_GETOWN_ARG 12 /* same as F_GETOWN, but uses arg */
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-v850/fcntl.h linux-2.6.5/include/asm-v850/fcntl.h
*** linux-2.6.5.orig/include/asm-v850/fcntl.h Sat Apr 3 19:36:53 2004
--- linux-2.6.5/include/asm-v850/fcntl.h Wed May 5 17:53:58 2004
***************
*** 39,44 ****
--- 39,46 ----
#define F_SETLK64 13
#define F_SETLKW64 14
+ #define F_GETOWN_ARG 15 /* same as F_GETOWN, but uses arg */
+
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
diff -rcN linux-2.6.5.orig/include/asm-x86_64/fcntl.h linux-2.6.5/include/asm-x86_64/fcntl.h
*** linux-2.6.5.orig/include/asm-x86_64/fcntl.h Sat Apr 3 19:36:26 2004
--- linux-2.6.5/include/asm-x86_64/fcntl.h Wed May 5 17:53:48 2004
***************
*** 34,39 ****
--- 34,40 ----
#define F_GETOWN 9 /* for sockets. */
#define F_SETSIG 10 /* for sockets. */
#define F_GETSIG 11 /* for sockets. */
+ #define F_GETOWN_ARG 12 /* same as F_GETOWN, but uses arg */
/* for F_[GET|SET]FL */
#define FD_CLOEXEC 1 /* actually anything with low bit set goes */
prev parent reply other threads:[~2004-05-06 1:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-05-04 1:26 errno Albert Cahalan
2004-05-04 4:14 ` errno Linus Torvalds
2004-05-04 5:58 ` errno Philippe Troin
2004-05-06 1:16 ` Philippe Troin [this message]
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