pthread cancellation points missing for fdatasync and lockf in some cases

[Carlos O'Donell]

On 5/5/07, Mike Frysinger <vapier@gentoo.org> wrote:
> POSIX requires fdatasync() and lockf() be pthread cancellation endpoints but
> it looks like they get missed a little in glibc ...

Is there a reference for this?

> fdatasync() is generated for Linux simply via syscalls.list as a pass through
> to the kernel... the generic case in misc/fdatasync.c relies on fsync() being
> a cancellation endpoint ... so here, just Linux is broken it seems

A patch for this would be to add "C" to the fdatasync signature in
syscalls.list.
See make-syscalls.sh.

> as for lockf(), this seems to be [incorrectly] done on purpose ... io/lockf.c
> talks about relying on fcntl()'s cancellation endpoint when called with
> F_SETLKW as that is the only case that POSIX says fcntl() should be a
> cancellation endpoint ... however, POSIX does not grant this limitation to
> lockf() ... it should always be a cancellation endpoint regardless of the
> arguments it is called with
> -mike

Use LIBC_CANCEL_ASYNC/LIBC_CANCEL_RESET to fix this.
Then write a test to prove it works? :-)

Care to file this in the bugzilla so we don't forget.

Cheers,
Carlos.