linux-kernel - [PATCH] mm/zswap: Add return value in zswap_frontswap

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Message-Id: <20210121214804.926843-1-natechancellor@gmail.com>
Date:   Thu, 21 Jan 2021 14:48:05 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Seth Jennings <sjenning@...hat.com>,
        Dan Streetman <ddstreet@...e.org>,
        Vitaly Wool <vitaly.wool@...sulko.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Tian Tao <tiantao6@...ilicon.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        Nathan Chancellor <natechancellor@...il.com>,
        "kernelci . org bot" <bot@...nelci.org>,
        kernel test robot <lkp@...el.com>
Subject: [PATCH] mm/zswap: Add return value in zswap_frontswap_load

Clang warns:

mm/zswap.c:1271:6: warning: variable 'ret' is used uninitialized
whenever 'if' condition is true [-Wsometimes-uninitialized]
        if (!entry->length) {
            ^~~~~~~~~~~~~~
mm/zswap.c:1322:9: note: uninitialized use occurs here
        return ret;
               ^~~
mm/zswap.c:1271:2: note: remove the 'if' if its condition is always
false
        if (!entry->length) {
        ^~~~~~~~~~~~~~~~~~~~~
mm/zswap.c:1259:9: note: initialize the variable 'ret' to silence this
warning
        int ret;
               ^
                = 0
1 warning generated.

Prior to "mm/zswap: add the flag can_sleep_mapped", this path always
returned 0. Restore that so we are not returning uninitialized memory.

Link: https://github.com/ClangBuiltLinux/linux/issues/1263
Reported-by: kernelci.org bot <bot@...nelci.org>
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---

Andrew, please fold this into

mm-zswap-add-the-flag-can_sleep_mapped.patch

 mm/zswap.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/zswap.c b/mm/zswap.c
index 6e0bb61d2a2c..a85334b719b9 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1272,6 +1272,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
 		dst = kmap_atomic(page);
 		zswap_fill_page(dst, entry->value);
 		kunmap_atomic(dst);
+		ret = 0;
 		goto freeentry;
 	}
 

base-commit: bc085f8fc88fc16796c9f2364e2bfb3fef305cad
-- 
2.30.0