Patchwork [3.5.y.z,extended,stable] Patch "mvsas: fix undefined bit shift" has been added to staging queue

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Submitter Herton Ronaldo Krzesinski
Date Jan. 7, 2013, 8:35 p.m.
Message ID <1357590951-19937-1-git-send-email-herton.krzesinski@canonical.com>
Download mbox | patch
Permalink /patch/210177/
State New
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Herton Ronaldo Krzesinski - Jan. 7, 2013, 8:35 p.m.
This is a note to let you know that I have just added a patch titled

    mvsas: fix undefined bit shift

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Herton

------

From 0629ae1a208cd48d790db43536580f0389cf8b56 Mon Sep 17 00:00:00 2001
From: Xi Wang <xi.wang@gmail.com>
Date: Fri, 16 Nov 2012 14:40:03 -0500
Subject: [PATCH] mvsas: fix undefined bit shift

commit beecadea1b8d67f591b13f7099559f32f3fd601d upstream.

The macro bit(n) is defined as ((u32)1 << n), and thus it doesn't work
with n >= 32, such as in mvs_94xx_assign_reg_set():

	if (i >= 32) {
		mvi->sata_reg_set |= bit(i);
		...
	}

The shift ((u32)1 << n) with n >= 32 also leads to undefined behavior.
The result varies depending on the architecture.

This patch changes bit(n) to do a 64-bit shift.  It also simplifies
mv_ffc64() using __ffs64(), since invoking ffz() with ~0 is undefined.

Signed-off-by: Xi Wang <xi.wang@gmail.com>
Acked-by: Xiangliang Yu <yuxiangl@marvell.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
 drivers/scsi/mvsas/mv_94xx.h |   14 ++------------
 drivers/scsi/mvsas/mv_sas.h  |    2 +-
 2 files changed, 3 insertions(+), 13 deletions(-)

--
1.7.9.5

Patch

diff --git a/drivers/scsi/mvsas/mv_94xx.h b/drivers/scsi/mvsas/mv_94xx.h
index 8f7eb4f..487aa6f 100644
--- a/drivers/scsi/mvsas/mv_94xx.h
+++ b/drivers/scsi/mvsas/mv_94xx.h
@@ -258,21 +258,11 @@  enum sas_sata_phy_regs {
 #define SPI_ADDR_VLD_94XX         	(1U << 1)
 #define SPI_CTRL_SpiStart_94XX     	(1U << 0)

-#define mv_ffc(x)   ffz(x)
-
 static inline int
 mv_ffc64(u64 v)
 {
-	int i;
-	i = mv_ffc((u32)v);
-	if (i >= 0)
-		return i;
-	i = mv_ffc((u32)(v>>32));
-
-	if (i != 0)
-		return 32 + i;
-
-	return -1;
+	u64 x = ~v;
+	return x ? __ffs64(x) : -1;
 }

 #define r_reg_set_enable(i) \
diff --git a/drivers/scsi/mvsas/mv_sas.h b/drivers/scsi/mvsas/mv_sas.h
index c04a4f5..da24955 100644
--- a/drivers/scsi/mvsas/mv_sas.h
+++ b/drivers/scsi/mvsas/mv_sas.h
@@ -69,7 +69,7 @@  extern struct kmem_cache *mvs_task_list_cache;
 #define DEV_IS_EXPANDER(type)	\
 	((type == EDGE_DEV) || (type == FANOUT_DEV))

-#define bit(n) ((u32)1 << n)
+#define bit(n) ((u64)1 << n)

 #define for_each_phy(__lseq_mask, __mc, __lseq)			\
 	for ((__mc) = (__lseq_mask), (__lseq) = 0;		\