On 8/22/19 6:14 AM, Stefan Hajnoczi wrote:

On Tue, Aug 20, 2019 at 10:29:58AM -0700, Bart Van Assche wrote:

quoted

Order head and tail stores properly against CQE / SQE memory accesses.
Use <asm/barrier.h> instead of the io_uring "barrier.h" header file.

Where does this header file come from?

Linux has an asm-generic/barrier.h file which is not uapi and therefore
not installed in /usr/include.

I couldn't find an asm/barrier.h in the Debian packages collection
either.

There two flavours of the asm/barrier.h header file present in the 
kernel tree. I think that the arch/*/include/asm/barrier.h header files 
are intended for kernel code and that the tools/include/asm/barrier.h 
header file is intended for the user space code in the tools directory.

Bart.