lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-Id: <20201028122102.24202-1-lukas.bulwahn@gmail.com>
Date:   Wed, 28 Oct 2020 13:21:02 +0100
From:   Lukas Bulwahn <lukas.bulwahn@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org
Cc:     "H . Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        kernel-janitors@...r.kernel.org, linux-safety@...ts.elisa.tech,
        Lukas Bulwahn <lukas.bulwahn@...il.com>
Subject: [PATCH] x86/unwind: remove unneeded initialization

make clang-analyzer on x86_64 defconfig caught my attention with:

  arch/x86/kernel/unwind_orc.c:38:7: warning: Value stored to 'mid' during
  its initialization is never read [clang-analyzer-deadcode.DeadStores]
          int *mid = first, *found = first;
               ^

Commit ee9f8fce9964 ("x86/unwind: Add the ORC unwinder") introduced
__orc_find() with this unneeded dead-store initialization.

Put the variable in local scope and initialize only once the value is
needed to make clang-analyzer happy.

As compilers will detect this unneeded assignment and optimize this
anyway, the resulting object code is effectively identical before and
after this change.

No functional change. Effectively, no change to object code.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
---
applies cleanly on current master and next-20201028

Josh, please ack.
Ingo, Borislav, please pick this minor non-urgent clean-up patch.

 arch/x86/kernel/unwind_orc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index 6a339ce328e0..5c64eed08257 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -35,7 +35,7 @@ static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
 {
 	int *first = ip_table;
 	int *last = ip_table + num_entries - 1;
-	int *mid = first, *found = first;
+	int *found = first;
 
 	if (!num_entries)
 		return NULL;
@@ -47,7 +47,7 @@ static struct orc_entry *__orc_find(int *ip_table, struct orc_entry *u_table,
 	 * ignored when they conflict with a real entry.
 	 */
 	while (first <= last) {
-		mid = first + ((last - first) / 2);
+		int *mid = first + ((last - first) / 2);
 
 		if (orc_ip(mid) <= ip) {
 			found = mid;
-- 
2.17.1

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ