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[PATCH 00/08] nptl: Fix Race conditions in pthread cancellation (BZ#12683)

Hi all,

This is an updated version of my previous patchset to fix BZ#12683 [1]

The patchset fixes the x86_64, i386, x32, powerpc32, powerpc64{le}, aarch64,
and ARM port. It will require some help for alpha, hppa, ia64, m68k, microblaze,
nios2, s390, sh, sparc, and tile. I summarized in wiki page [2] the steps
required to adjust the remaining architectures, but based on arm/aarch64 the
minimal adjustments required are:

1. Write a new syscall implementation at sysdeps/unix/sysv/linux/<arch>/syscall_cancel.S
   that basically do:

long int __syscall_cancel_arch (volatile unsigned int *cancelhandling,
  __syscall_arg_t nr, __syscall_arg_t arg1, __syscall_arg_t arg2, 
  __syscall_arg_t arg3, __syscall_arg_t arg4, __syscall_arg_t arg5,
  __syscall_arg_t arg6)
  if (*cancelhandling & CANCELED_BITMASK)

  return INLINE_SYSCALL (nr, 6, arg1, arg2, arg3, arg4, arg5, arg6);

2. Adjust sysdeps/unix/sysv/linux/<arch>/sysdep-cancel.h to make cancellable
   syscalls to call __syscall_cancel instead of *_{enable,disable}_asynccancel.

3. Create a function to get current IP address based on ucontext_t:

static inline
long int __pthread_get_ip (const struct ucontext *uc)
  // TODO

4. Define both SYSCALL_CANCEL_ERROR(__val) and SYSCALL_CANCEL_ERRNO(__val)

For x86_64 and i386 implementation my approach was to just remove the
pthread_cond_{timed}wait assembly implementation and use default C code, but
since Torvald Riegel new condvar implementation [3] also removed them this
patchset do not contain such removals. Also, this fix is easy to adjust
to new futex API also proposed by Torvalds and I can adjust the patch when
the new API is pushed upstream. The bulk of implementation just depend of a
cancellable futex call done by new mechanism which is orthogonal of the new
proposed futex API.

The idea is try to push it for 2.23 and I have a personal branch [4] with
a working tree for the aforementioned architectures plus some skeleton for
s390 and s390x (not working thou).


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