Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Zhangjin Wu <falcon@tinylab.org>
To:     w@1wt.eu
Cc:     david.laight@aculab.com, arnd@arndb.de, falcon@tinylab.org,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        linux-riscv@lists.infradead.org, thomas@t-8ch.de,
        =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= <linux@weissschuh.net>
Subject: [PATCH v4 01/10] tools/nolibc: sys.h: add a syscall return helper
Date:   Mon, 19 Jun 2023 23:41:18 +0800
Message-Id: <c6e6077660db1d07fdf92d89dac3641ce8195851.1687187451.git.falcon@tinylab.org>
In-Reply-To: <cover.1687187451.git.falcon@tinylab.org>
References: <cover.1687187451.git.falcon@tinylab.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Feedback-ID: bizesmtp:tinylab.org:qybglogicsvrsz:qybglogicsvrsz3a-3
Precedence: bulk

Most of the library routines share the same syscall return logic:

  In general, a 0 return value indicates success.  A -1 return value
  indicates an error, and an error number is stored in errno. [1]

Let's add a __sysret() helper for the above logic to simplify the coding
and shrink the code lines too.

Thomas suggested to use inline function instead of macro for __sysret().

Willy suggested to make __sysret() be always inline.

[1]: https://man7.org/linux/man-pages/man2/syscall.2.html

Suggested-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/linux-riscv/ZH1+hkhiA2+ItSvX@1wt.eu/
Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/linux-riscv/ea4e7442-7223-4211-ba29-70821e907888@t-8ch.de/
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
---
 tools/include/nolibc/sys.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 856249a11890..150777207468 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -28,6 +28,16 @@
 #include "errno.h"
 #include "types.h"
 
+/* Syscall return helper, set errno as -ret when ret < 0 */
+static __inline__ __attribute__((unused, always_inline))
+long __sysret(long ret)
+{
+	if (ret < 0) {
+		SET_ERRNO(-ret);
+		ret = -1;
+	}
+	return ret;
+}
 
 /* Functions in this file only describe syscalls. They're declared static so
  * that the compiler usually decides to inline them while still being allowed
-- 
2.25.1