[LTP] [PATCH] syscalls/fcntl: make OFD commands use fcntl64() syscall on 32-bit

[Li Wang]

On Mon, Sep 17, 2018 at 4:53 PM, Jan Stancek <jstancek@redhat.com> wrote:

> OFD commands require 64-bit argument (struct flock64). Until
> glibc commit 06ab719d30b0 ("Fix Linux fcntl OFD locks for
> non-LFS architectures (BZ#20251)") we relied on glibc passing
> arg directly to syscall.
>
> This creates problem for 32-bit version of the test, because old
> glibc is passing arg directly, while new one is casting it to
> struct flock.
>
> We could add a configure check for glibc version, but that may
> not help with other libc libraries.
>
> We could do a runtime check that exploits non-zero l_pid returning
> EINVAL. This however complicates SAFE_FCNTL macro substantially.
>
> This patch changes 32-bit version of test to use syscall directly.
>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
> ---
>  testcases/kernel/syscalls/fcntl/fcntl34.c      | 10 ++++++--
>  testcases/kernel/syscalls/fcntl/fcntl36.c      | 19 +++++++++++----
>  testcases/kernel/syscalls/fcntl/fcntl_common.h | 33
> ++++++++++++++++++++++++++
>  3 files changed, 56 insertions(+), 6 deletions(-)
>  create mode 100644 testcases/kernel/syscalls/fcntl/fcntl_common.h
>
> diff --git a/testcases/kernel/syscalls/fcntl/fcntl34.c
> b/testcases/kernel/syscalls/fcntl/fcntl34.c
> index aa29cf9ea0d8..90c40f9cf4c6 100644
> --- a/testcases/kernel/syscalls/fcntl/fcntl34.c
> +++ b/testcases/kernel/syscalls/fcntl/fcntl34.c
> @@ -28,6 +28,7 @@
>  #include "lapi/fcntl.h"
>  #include "tst_safe_pthread.h"
>  #include "tst_test.h"
> +#include "fcntl_common.h"
>
>  static int thread_cnt;
>  static const int max_thread_cnt = 32;
> @@ -68,7 +69,12 @@ void *thread_fn_01(void *arg)
>
>         memset(buf, (intptr_t)arg, write_size);
>
> +/* see explanation in fcntl_common.h */
> +#ifdef USE_STRUCT_FLOCK64
>         struct flock64 lck = {
> +#else
> +       struct flock lck = {
> +#endif
>

It seems the 'struct flock64' can satisfy both 64-bit and 32-bit platform,
why here adding 'struct flock' here? Eventually, as the code comment says:
On 32-bit, ..., recent one treats it as 'struct flock' and converts it to
'struct flock64'. Why not use 'struct flock64'  directly?

-- 
Regards,
Li Wang
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