linux-kernel - [PATCH] memstick: r592: ignore kfifo

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Message-Id: <20210421135215.3414589-1-arnd@kernel.org>
Date:   Wed, 21 Apr 2021 15:51:58 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     Maxim Levitsky <maximlevitsky@...il.com>,
        Alex Dubov <oakad@...oo.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Jing Xiangfeng <jingxiangfeng@...wei.com>,
        Jiapeng Chong <jiapeng.chong@...ux.alibaba.com>,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: [PATCH] memstick: r592: ignore kfifo_out() return code again

From: Arnd Bergmann <arnd@...db.de>

A minor cleanup to address a clang warning removed an assigned
but unused local variable, but this now caused a gcc warning as
kfifo_out() is annotated to require checking its return code:

In file included from drivers/memstick/host/r592.h:13,
                 from drivers/memstick/host/r592.c:21:
drivers/memstick/host/r592.c: In function 'r592_flush_fifo_write':
include/linux/kfifo.h:588:1: error: ignoring return value of '__kfifo_uint_must_check_helper' declared with attribute 'warn_unused_result' [-Werror=unused-result]
  588 | __kfifo_uint_must_check_helper( \
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  589 | ({ \
      | ~~~~
  590 |         typeof((fifo) + 1) __tmp = (fifo); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  591 |         typeof(__tmp->ptr) __buf = (buf); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  592 |         unsigned long __n = (n); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~
  593 |         const size_t __recsize = sizeof(*__tmp->rectype); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  594 |         struct __kfifo *__kfifo = &__tmp->kfifo; \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  595 |         (__recsize) ?\
      |         ~~~~~~~~~~~~~~
  596 |         __kfifo_out_r(__kfifo, __buf, __n, __recsize) : \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  597 |         __kfifo_out(__kfifo, __buf, __n); \
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  598 | }) \
      | ~~~~
  599 | )
      | ~
drivers/memstick/host/r592.c:367:9: note: in expansion of macro 'kfifo_out'
  367 |         kfifo_out(&dev->pio_fifo, buffer, 4);
      |         ^~~~~~~~~

The value was never checked here, and the purpose of the function
is only to flush the contents, so restore the old behavior but
add a cast to void and a comment, which hopefully warns with neither
gcc nor clang now.

If anyone has an idea for how to fix it without ignoring the return
code, that is probably better.

Fixes: 4b00ed3c5072 ("memstick: r592: remove unused variable")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/memstick/host/r592.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/memstick/host/r592.c b/drivers/memstick/host/r592.c
index 026fadaa1d5d..615a83782e55 100644
--- a/drivers/memstick/host/r592.c
+++ b/drivers/memstick/host/r592.c
@@ -359,12 +359,15 @@ static void r592_write_fifo_pio(struct r592_device *dev,
 /* Flushes the temporary FIFO used to make aligned DWORD writes */
 static void r592_flush_fifo_write(struct r592_device *dev)
 {
+	int ret;
 	u8 buffer[4] = { 0 };
 
 	if (kfifo_is_empty(&dev->pio_fifo))
 		return;
 
-	kfifo_out(&dev->pio_fifo, buffer, 4);
+	ret = kfifo_out(&dev->pio_fifo, buffer, 4);
+	/* intentionally ignore __must_check return code */
+	(void)ret;
 	r592_write_reg_raw_be(dev, R592_FIFO_PIO, *(u32 *)buffer);
 }
 
-- 
2.29.2