linux-kernel - [RFC][PATCH] futex: Hide false positive about uninit var usage

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Date:	Tue, 16 Nov 2010 10:32:37 -0600
From:	Sergio Aguirre <saaguirre@...com>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	Sergio Aguirre <saaguirre@...com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Darren Hart <dvhart@...ux.intel.com>,
	Ingo Molnar <mingo@...e.hu>, Namhyung Kim <namhyung@...il.com>
Subject: [RFC][PATCH] futex: Hide false positive about uninit var usage

In exit_robust_list, there was this warning shown:

kernel/futex.c: In function 'exit_robust_list':
kernel/futex.c:2492: warning: 'next_pi' may be used uninitialized in this function

Which is a false positive, since in the function, the only scenario
possible in which the var is read, is after a successful excecution of
fetch_robust_entry, which populates the variable.

So there's no real possibility of it being used uninitialized.

Signed-off-by: Sergio Aguirre <saaguirre@...com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Darren Hart <dvhart@...ux.intel.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Namhyung Kim <namhyung@...il.com>
---
 kernel/futex.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 6c683b3..3646157 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2489,7 +2489,8 @@ void exit_robust_list(struct task_struct *curr)
 {
 	struct robust_list_head __user *head = curr->robust_list;
 	struct robust_list __user *entry, *next_entry, *pending;
-	unsigned int limit = ROBUST_LIST_LIMIT, pi, next_pi, pip;
+	unsigned int limit = ROBUST_LIST_LIMIT, pi;
+	unsigned int uninitialized_var(next_pi), pip;
 	unsigned long futex_offset;
 	int rc;
 
-- 
1.7.0.4

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