Commit 2882c48b authored by Björn Töpel's avatar Björn Töpel Committed by Andrii Nakryiko
Browse files

libbpf: xsk: Remove linux/compiler.h header 



In commit 291471dd ("libbpf, xsk: Add libbpf_smp_store_release
libbpf_smp_load_acquire") linux/compiler.h was added as a dependency
to xsk.h, which is the user-facing API. This makes it harder for
userspace application to consume the library. Here the header
inclusion is removed, and instead {READ,WRITE}_ONCE() is added
explicitly.

Signed-off-by: default avatarBjörn Töpel <bjorn.topel@intel.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210310080929.641212-2-bjorn.topel@gmail.com
parent a9c80b03

tools/lib/bpf/libbpf_util.h

+17 −10
Original line number Diff line number Diff line
@@ -5,25 +5,30 @@ 
#define __LIBBPF_LIBBPF_UTIL_H



#include <stdbool.h>

#include <linux/compiler.h>



#ifdef __cplusplus

extern "C" {

#endif



/* Use these barrier functions instead of smp_[rw]mb() when they are

 * used in a libbpf header file. That way they can be built into the

 * application that uses libbpf.

/* Load-Acquire Store-Release barriers used by the XDP socket

 * library. The following macros should *NOT* be considered part of

 * the xsk.h API, and is subject to change anytime.

 *

 * LIBRARY INTERNAL

 */



#define __XSK_READ_ONCE(x) (*(volatile typeof(x) *)&x)

#define __XSK_WRITE_ONCE(x, v) (*(volatile typeof(x) *)&x) = (v)



#if defined(__i386__) || defined(__x86_64__)

# define libbpf_smp_store_release(p, v)					\

	do {								\

		asm volatile("" : : : "memory");			\

		WRITE_ONCE(*p, v);					\

		__XSK_WRITE_ONCE(*p, v);				\

	} while (0)

# define libbpf_smp_load_acquire(p)					\

	({								\

		typeof(*p) ___p1 = READ_ONCE(*p);			\

		typeof(*p) ___p1 = __XSK_READ_ONCE(*p);			\

		asm volatile("" : : : "memory");			\

		___p1;							\

	})
@@ -41,11 +46,11 @@ extern "C" { 
# define libbpf_smp_store_release(p, v)					\

	do {								\

		asm volatile ("fence rw,w" : : : "memory");		\

		WRITE_ONCE(*p, v);					\

		__XSK_WRITE_ONCE(*p, v);				\

	} while (0)

# define libbpf_smp_load_acquire(p)					\

	({								\

		typeof(*p) ___p1 = READ_ONCE(*p);			\

		typeof(*p) ___p1 = __XSK_READ_ONCE(*p);			\

		asm volatile ("fence r,rw" : : : "memory");		\

		___p1;							\

	})
@@ -55,19 +60,21 @@ extern "C" { 
#define libbpf_smp_store_release(p, v)					\

	do {								\

		__sync_synchronize();					\

		WRITE_ONCE(*p, v);					\

		__XSK_WRITE_ONCE(*p, v);				\

	} while (0)

#endif



#ifndef libbpf_smp_load_acquire

#define libbpf_smp_load_acquire(p)					\

	({								\

		typeof(*p) ___p1 = READ_ONCE(*p);			\

		typeof(*p) ___p1 = __XSK_READ_ONCE(*p);			\

		__sync_synchronize();					\

		___p1;							\

	})

#endif



/* LIBRARY INTERNAL -- END */



#ifdef __cplusplus

} /* extern "C" */

#endif