[ 018/171] SCSI: mvsas: fix undefined bit shift

Greg Kroah-Hartman
2013-01-15T22:47:13Z

From: Xi Wang <xi.wang@gmail.com>

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/mvsas/mv_94xx.h | 14 ++------------
drivers/scsi/mvsas/mv_sas.h | 2 +-
2 files changed, 3 insertions(+), 13 deletions(-)

--- 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) \
--- 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_
#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; \