linux-kernel - [PATCH] clk: s2mps11: Add used attribute to s2mps11_dt

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Message-Id: <20181018191340.30440-1-natechancellor@gmail.com>
Date:   Thu, 18 Oct 2018 12:13:40 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Sangbeom Kim <sbkim73@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
        linux-clk@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>
Subject: [PATCH] clk: s2mps11: Add used attribute to s2mps11_dt_match

Clang warns after commit 8985167ecf57 ("clk: s2mps11: Fix matching when
built as module and DT node contains compatible"):

drivers/clk/clk-s2mps11.c:242:34: warning: variable 's2mps11_dt_match'
is not needed and will not be emitted [-Wunneeded-internal-declaration]
static const struct of_device_id s2mps11_dt_match[] = {
                                 ^
1 warning generated.

This warning happens when a variable is used in some construct that
doesn't require a reference to that variable to be emitted in the symbol
table; in this case, it's MODULE_DEVICE_TABLE, which only needs to hold
the data of the variable, not the variable itself.

$ nm -S drivers/clk/clk-s2mps11.o | rg s2mps11_dt_match
00000078 000003d4 R __mod_of__s2mps11_dt_match_device_table

Normally, with device ID table variables, it means that the variable
just needs to be tied to the device declaration at the bottom of the
file, like s2mps11_clk_id:

$ nm -S drivers/clk/clk-s2mps11.o | rg s2mps11_clk_id
00000000 00000078 R __mod_platform__s2mps11_clk_id_device_table
00000000 00000078 r s2mps11_clk_id

However, because the comment above this deliberately doesn't want this
variable added to .of_match_table, we need to mark s2mps11_dt_match as
__used to silence this warning. This makes it clear to Clang that the
variable is used for something, even if a reference to it isn't being
emitted.

Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 drivers/clk/clk-s2mps11.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/clk-s2mps11.c b/drivers/clk/clk-s2mps11.c
index 9c2e6be392e3..5b419b82f7ca 100644
--- a/drivers/clk/clk-s2mps11.c
+++ b/drivers/clk/clk-s2mps11.c
@@ -239,7 +239,7 @@ MODULE_DEVICE_TABLE(platform, s2mps11_clk_id);
  * This requires of_device_id table.  In the same time this will not change the
  * actual *device* matching so do not add .of_match_table.
  */
-static const struct of_device_id s2mps11_dt_match[] = {
+static const struct of_device_id s2mps11_dt_match[] __used = {
 	{
 		.compatible = "samsung,s2mps11-clk",
 		.data = (void *)S2MPS11X,
-- 
2.19.1