[PATCH v2] xen/bitmap: Don't open code DIV_ROUND_UP()

[PATCH v2] xen/bitmap: Don't open code DIV_ROUND_UP()

[Jane Malalane]

Also, change bitmap_long_to_byte() and bitmap_byte_to_long() to take
'unsigned int' instead of 'int' number of bits, to match the type of
their callers.

Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jane Malalane <jane.malalane@citrix.com>
---
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: George Dunlap <george.dunlap@citrix.com>
CC: Ian Jackson <iwj@xenproject.org>
CC: Jan Beulich <jbeulich@suse.com>
CC: Julien Grall <julien@xen.org>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Wei Liu <wl@xen.org>

v2:
 * Reorder #include and wrap text
---
 xen/common/bitmap.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)

diff --git a/xen/common/bitmap.c b/xen/common/bitmap.c
index bbc3554ae1..7d4551f782 100644
--- a/xen/common/bitmap.c
+++ b/xen/common/bitmap.c
@@ -11,6 +11,7 @@
 #include <xen/bitops.h>
 #include <xen/cpumask.h>
 #include <xen/guest_access.h>
+#include <xen/lib.h>
 #include <asm/byteorder.h>
 
 /*
@@ -338,7 +339,8 @@ EXPORT_SYMBOL(bitmap_allocate_region);
 
 #ifdef __BIG_ENDIAN
 
-static void bitmap_long_to_byte(uint8_t *bp, const unsigned long *lp, int nbits)
+static void bitmap_long_to_byte(uint8_t *bp, const unsigned long *lp,
+				unsigned int nbits)
 {
 	unsigned long l;
 	int i, j, b;
@@ -354,7 +356,8 @@ static void bitmap_long_to_byte(uint8_t *bp, const unsigned long *lp, int nbits)
 	clamp_last_byte(bp, nbits);
 }
 
-static void bitmap_byte_to_long(unsigned long *lp, const uint8_t *bp, int nbits)
+static void bitmap_byte_to_long(unsigned long *lp, const uint8_t *bp,
+				unsigned int nbits)
 {
 	unsigned long l;
 	int i, j, b;
@@ -371,18 +374,20 @@ static void bitmap_byte_to_long(unsigned long *lp, const uint8_t *bp, int nbits)
 
 #elif defined(__LITTLE_ENDIAN)
 
-static void bitmap_long_to_byte(uint8_t *bp, const unsigned long *lp, int nbits)
+static void bitmap_long_to_byte(uint8_t *bp, const unsigned long *lp,
+				unsigned int nbits)
 {
-	memcpy(bp, lp, (nbits+7)/8);
+	memcpy(bp, lp, DIV_ROUND_UP(nbits, BITS_PER_BYTE));
 	clamp_last_byte(bp, nbits);
 }
 
-static void bitmap_byte_to_long(unsigned long *lp, const uint8_t *bp, int nbits)
+static void bitmap_byte_to_long(unsigned long *lp, const uint8_t *bp,
+				unsigned int nbits)
 {
 	/* We may need to pad the final longword with zeroes. */
 	if (nbits & (BITS_PER_LONG-1))
 		lp[BITS_TO_LONGS(nbits)-1] = 0;
-	memcpy(lp, bp, (nbits+7)/8);
+	memcpy(lp, bp, DIV_ROUND_UP(nbits, BITS_PER_BYTE));
 }
 
 #endif
@@ -393,13 +398,14 @@ int bitmap_to_xenctl_bitmap(struct xenctl_bitmap *xenctl_bitmap,
     unsigned int guest_bytes, copy_bytes, i;
     uint8_t zero = 0;
     int err = 0;
-    uint8_t *bytemap = xmalloc_array(uint8_t, (nbits + 7) / 8);
+    unsigned int xen_bytes = DIV_ROUND_UP(nbits, BITS_PER_BYTE);
+    uint8_t *bytemap = xmalloc_array(uint8_t, xen_bytes);
 
     if ( !bytemap )
         return -ENOMEM;
 
-    guest_bytes = (xenctl_bitmap->nr_bits + 7) / 8;
-    copy_bytes  = min(guest_bytes, (nbits + 7) / 8);
+    guest_bytes = DIV_ROUND_UP(xenctl_bitmap->nr_bits, BITS_PER_BYTE);
+    copy_bytes  = min(guest_bytes, xen_bytes);
 
     bitmap_long_to_byte(bytemap, bitmap, nbits);
 
@@ -422,13 +428,14 @@ int xenctl_bitmap_to_bitmap(unsigned long *bitmap,
 {
     unsigned int guest_bytes, copy_bytes;
     int err = 0;
-    uint8_t *bytemap = xzalloc_array(uint8_t, (nbits + 7) / 8);
+    unsigned int xen_bytes = DIV_ROUND_UP(nbits, BITS_PER_BYTE);
+    uint8_t *bytemap = xzalloc_array(uint8_t, xen_bytes);
 
     if ( !bytemap )
         return -ENOMEM;
 
-    guest_bytes = (xenctl_bitmap->nr_bits + 7) / 8;
-    copy_bytes  = min(guest_bytes, (nbits + 7) / 8);
+    guest_bytes = DIV_ROUND_UP(xenctl_bitmap->nr_bits, BITS_PER_BYTE);
+    copy_bytes  = min(guest_bytes, xen_bytes);
 
     if ( copy_bytes )
     {
-- 
2.11.0

Re: [PATCH v2] xen/bitmap: Don't open code DIV_ROUND_UP()

[Jan Beulich]

On 12.08.2021 12:02, Jane Malalane wrote:
> Also, change bitmap_long_to_byte() and bitmap_byte_to_long() to take
> 'unsigned int' instead of 'int' number of bits, to match the type of
> their callers.
> 
> Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Jane Malalane <jane.malalane@citrix.com>

Reviewed-by: Jan Beulich <jbeulich@suse.com>