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Date: Thu, 6 Jul 2017 16:46:02 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [git pull] vfs.git part 3
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On Thu, Jul 06, 2017 at 05:10:33PM +0200, Christoph Hellwig wrote:
> On Thu, Jul 06, 2017 at 04:03:30PM +0100, Al Viro wrote:
> > On Thu, Jul 06, 2017 at 04:48:40PM +0200, Christoph Hellwig wrote:
> > 
> > > Just did the whole batch (patch below), but it seems like using a
> > > __bitwise type in SYSCALL_DEFINE* will always give warnings like:
> > > 
> > > fs/read_write.c:1095:1: warning: cast to restricted __kernel_rwf_t
> > > 
> > > which I'm not sure to deal with..
> > 
> > #define __SC_CAST(t, a) (__force t) a
> 
> doesn't seem to make a difference..

Works here...

; cat a.c
#include <linux/syscalls.h>
#undef __SC_CAST
#define __SC_CAST(t, a) (__force t)a
typedef int __bitwise __foo_t;
static __foo_t is_OK;
static int will_warn;
SYSCALL_DEFINE1(foo, __foo_t, arg)
{
        is_OK = arg;
        will_warn = arg;
        return 0;
}
; make a.o C=2 CHECK=~/local/sparse/sparse 
  CHK     include/config/kernel.release
  CHK     include/generated/uapi/linux/version.h
  CHK     include/generated/utsrelease.h
  CHECK   arch/x86/purgatory/purgatory.c
  CHECK   arch/x86/purgatory/sha256.c
  CHECK   arch/x86/purgatory/string.c
arch/x86/purgatory/../boot/string.c:165:6: warning: symbol 'strchr' was not declared. Should it be static?
  CHK     include/generated/bounds.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/asm-offsets.h
  CALL    scripts/checksyscalls.sh
  DESCEND  objtool
  CHECK   scripts/mod/empty.c
  CHK     scripts/mod/devicetable-offsets.h
  CHK     include/generated/timeconst.h
  CHK     include/generated/bounds.h
  CHECK   a.c
a.c:10:19: warning: incorrect type in assignment (different base types)
a.c:10:19:    expected int static [signed] [toplevel] will_warn
a.c:10:19:    got restricted __foo_t [usertype] arg
  CC      a.o
;

That - on #work.read_write, as in vfs.git at the moment...