On Thu, 17 Sep 2020 at 07:34, Andreas Schwab <schwab@xxxxxxxxxxxxxx> wrote: > > On Sep 17 2020, Arnd Bergmann wrote: > > > The errno man page says they are supposed to be synonyms, > > and glibc defines it that way, while musl uses the numbers > > from the kernel. > > glibc also uses whatever the kernel defines. > That's right, and from my investigation this isn't a libc issue. The various libc flavours simply try to follow POSIX and the PPC ABI and aren't doing anything wrong. See errno.h for example (https://man7.org/linux/man-pages/man3/errno.3.html): EDEADLK: Resource deadlock avoided (POSIX.1-2001). EDEADLOCK: On most architectures, a synonym for EDEADLK. On some architectures (e.g., Linux MIPS, PowerPC, SPARC), it is a separate error code "File locking deadlock error". The root cause is unique to the Linux PPC code in arch/powerpc/include/uapi/asm/errno.h: >/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ >#ifndef _ASM_POWERPC_ERRNO_H >#define _ASM_POWERPC_ERRNO_H > >#include <asm-generic/errno.h> > >#undef EDEADLOCK >#define EDEADLOCK 58 /* File locking deadlock error */ > >#endif /* _ASM_POWERPC_ERRNO_H */ It includes "<asm-generic/errno.h>" to pull in various definitions but has the side-effect of redefining EDEADLOCK to a non-ABI value which conflicts with the libc errno.h, as I outline in the patch description. Other arches which also use different EDEADLOCK and EDEADLK values (mips,sparc) do not do this. They define EDEADLOCK *once*, with an ABI-consistent value, and don't have the same issue. The problem goes back a ways (as Arnd points out), affecting current stable and all LTS branches, so would be nice to get this sorted out. I'm certainly interested if there's a better way than proposed in this patch. > Andreas. > > -- > Andreas Schwab, schwab@xxxxxxxxxxxxxx > GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 > "And now for something completely different."
