linux-kernel - [PATCH] btrfs: avoid uninitialized variable warning

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Date:	Mon, 22 Feb 2016 22:53:20 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
	David Sterba <dsterba@...e.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Arnd Bergmann <arnd@...db.de>, linux-btrfs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] btrfs: avoid uninitialized variable warning

With CONFIG_SMP and CONFIG_PREEMPT both disabled, gcc decides
to partially inline the get_state_failrec() function but cannot
figure out that means the failrec pointer is always valid
if the function returns success, which causes a harmless
warning:

fs/btrfs/extent_io.c: In function 'clean_io_failure':
fs/btrfs/extent_io.c:2131:4: error: 'failrec' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This marks get_state_failrec() and set_state_failrec() both
as 'noinline', which avoids the warning in all cases for me,
and seems less ugly than adding a fake initialization.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Fixes: 47dc196ae719 ("btrfs: use proper type for failrec in extent_state")
---
 fs/btrfs/extent_io.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 27577f1b10dc..76a0c8597d98 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1842,7 +1842,7 @@ out:
  * set the private field for a given byte offset in the tree.  If there isn't
  * an extent_state there already, this does nothing.
  */
-static int set_state_failrec(struct extent_io_tree *tree, u64 start,
+static noinline int set_state_failrec(struct extent_io_tree *tree, u64 start,
 		struct io_failure_record *failrec)
 {
 	struct rb_node *node;
@@ -1870,7 +1870,7 @@ out:
 	return ret;
 }
 
-static int get_state_failrec(struct extent_io_tree *tree, u64 start,
+static noinline int get_state_failrec(struct extent_io_tree *tree, u64 start,
 		struct io_failure_record **failrec)
 {
 	struct rb_node *node;
-- 
2.7.0