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[PATCH] xen-blkfront: Use kcalloc instead of kzalloc to allocate array
thomas at m3y3r
Nov 29, 2011, 1:08 PM
Post #1 of 3 (140 views)
Permalink
The advantage of kcalloc is, that will prevent integer overflows which could
result from the multiplication of number of elements and size and it is also
a bit nicer to read.

The semantic patch that makes this change is available
in https://lkml.org/lkml/2011/11/25/107

Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
---

diff -u -p a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
--- a/drivers/block/cciss_scsi.c 2011-11-28 19:36:47.343430551 +0100
+++ b/drivers/block/cciss_scsi.c 2011-11-28 19:49:24.922716381 +0100
@@ -534,10 +534,10 @@ adjust_cciss_scsi_table(ctlr_info_t *h,
int nadded, nremoved;
struct Scsi_Host *sh = NULL;

- added = kzalloc(sizeof(*added) * CCISS_MAX_SCSI_DEVS_PER_HBA,
- GFP_KERNEL);
- removed = kzalloc(sizeof(*removed) * CCISS_MAX_SCSI_DEVS_PER_HBA,
+ added = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA, sizeof(*added),
GFP_KERNEL);
+ removed = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA, sizeof(*removed),
+ GFP_KERNEL);

if (!added || !removed) {
dev_warn(&h->pdev->dev,
@@ -1191,8 +1191,8 @@ cciss_update_non_disk_devices(ctlr_info_

ld_buff = kzalloc(reportlunsize, GFP_KERNEL);
inq_buff = kmalloc(OBDR_TAPE_INQ_SIZE, GFP_KERNEL);
- currentsd = kzalloc(sizeof(*currentsd) *
- (CCISS_MAX_SCSI_DEVS_PER_HBA+1), GFP_KERNEL);
+ currentsd = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA + 1,
+ sizeof(*currentsd), GFP_KERNEL);
if (ld_buff == NULL || inq_buff == NULL || currentsd == NULL) {
printk(KERN_ERR "cciss: out of memory\n");
goto out;
diff -u -p a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
--- a/drivers/block/xen-blkfront.c 2011-11-13 11:07:22.680095573 +0100
+++ b/drivers/block/xen-blkfront.c 2011-11-28 19:49:29.109460410 +0100
@@ -156,7 +156,7 @@ static int xlbd_reserve_minors(unsigned
if (end > nr_minors) {
unsigned long *bitmap, *old;

- bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
+ bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
GFP_KERNEL);
if (bitmap == NULL)
return -ENOMEM;

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Re: [PATCH] xen-blkfront: Use kcalloc instead of kzalloc to allocate array [ In reply to ]
konrad.wilk at oracle
Dec 5, 2011, 7:27 PM
Post #2 of 3 (134 views)
Permalink
On Tue, Nov 29, 2011 at 10:08:00PM +0100, Thomas Meyer wrote:
> The advantage of kcalloc is, that will prevent integer overflows which could
> result from the multiplication of number of elements and size and it is also
> a bit nicer to read.
>
> The semantic patch that makes this change is available
> in https://lkml.org/lkml/2011/11/25/107
>
> Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
> ---
>
> diff -u -p a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
> --- a/drivers/block/cciss_scsi.c 2011-11-28 19:36:47.343430551 +0100
> +++ b/drivers/block/cciss_scsi.c 2011-11-28 19:49:24.922716381 +0100
> @@ -534,10 +534,10 @@ adjust_cciss_scsi_table(ctlr_info_t *h,
> int nadded, nremoved;
> struct Scsi_Host *sh = NULL;
>
> - added = kzalloc(sizeof(*added) * CCISS_MAX_SCSI_DEVS_PER_HBA,
> - GFP_KERNEL);
> - removed = kzalloc(sizeof(*removed) * CCISS_MAX_SCSI_DEVS_PER_HBA,
> + added = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA, sizeof(*added),
> GFP_KERNEL);
> + removed = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA, sizeof(*removed),
> + GFP_KERNEL);
>

It looks like you mixed two patches together.

> if (!added || !removed) {
> dev_warn(&h->pdev->dev,
> @@ -1191,8 +1191,8 @@ cciss_update_non_disk_devices(ctlr_info_
>
> ld_buff = kzalloc(reportlunsize, GFP_KERNEL);
> inq_buff = kmalloc(OBDR_TAPE_INQ_SIZE, GFP_KERNEL);
> - currentsd = kzalloc(sizeof(*currentsd) *
> - (CCISS_MAX_SCSI_DEVS_PER_HBA+1), GFP_KERNEL);
> + currentsd = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA + 1,
> + sizeof(*currentsd), GFP_KERNEL);
> if (ld_buff == NULL || inq_buff == NULL || currentsd == NULL) {
> printk(KERN_ERR "cciss: out of memory\n");
> goto out;
> diff -u -p a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> --- a/drivers/block/xen-blkfront.c 2011-11-13 11:07:22.680095573 +0100
> +++ b/drivers/block/xen-blkfront.c 2011-11-28 19:49:29.109460410 +0100
> @@ -156,7 +156,7 @@ static int xlbd_reserve_minors(unsigned
> if (end > nr_minors) {
> unsigned long *bitmap, *old;
>
> - bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
> + bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
> GFP_KERNEL);

But this parts looks good.

Can you respin it with just that part please?
> if (bitmap == NULL)
> return -ENOMEM;
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/

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Re: [PATCH] xen-blkfront: Use kcalloc instead of kzalloc to allocate array [ In reply to ]
konrad.wilk at oracle
Dec 14, 2011, 10:56 AM
Post #3 of 3 (129 views)
Permalink
On Tue, Nov 29, 2011 at 10:08:00PM +0100, Thomas Meyer wrote:
> The advantage of kcalloc is, that will prevent integer overflows which could
> result from the multiplication of number of elements and size and it is also
> a bit nicer to read.
>
> The semantic patch that makes this change is available
> in https://lkml.org/lkml/2011/11/25/107
>

Thomas,

I put the xen-blkfront part of the patch in my tree and dropped the cciss_scsi one.

> Signed-off-by: Thomas Meyer <thomas@m3y3r.de>
> ---
>
> diff -u -p a/drivers/block/cciss_scsi.c b/drivers/block/cciss_scsi.c
> --- a/drivers/block/cciss_scsi.c 2011-11-28 19:36:47.343430551 +0100
> +++ b/drivers/block/cciss_scsi.c 2011-11-28 19:49:24.922716381 +0100
> @@ -534,10 +534,10 @@ adjust_cciss_scsi_table(ctlr_info_t *h,
> int nadded, nremoved;
> struct Scsi_Host *sh = NULL;
>
> - added = kzalloc(sizeof(*added) * CCISS_MAX_SCSI_DEVS_PER_HBA,
> - GFP_KERNEL);
> - removed = kzalloc(sizeof(*removed) * CCISS_MAX_SCSI_DEVS_PER_HBA,
> + added = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA, sizeof(*added),
> GFP_KERNEL);
> + removed = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA, sizeof(*removed),
> + GFP_KERNEL);
>
> if (!added || !removed) {
> dev_warn(&h->pdev->dev,
> @@ -1191,8 +1191,8 @@ cciss_update_non_disk_devices(ctlr_info_
>
> ld_buff = kzalloc(reportlunsize, GFP_KERNEL);
> inq_buff = kmalloc(OBDR_TAPE_INQ_SIZE, GFP_KERNEL);
> - currentsd = kzalloc(sizeof(*currentsd) *
> - (CCISS_MAX_SCSI_DEVS_PER_HBA+1), GFP_KERNEL);
> + currentsd = kcalloc(CCISS_MAX_SCSI_DEVS_PER_HBA + 1,
> + sizeof(*currentsd), GFP_KERNEL);
> if (ld_buff == NULL || inq_buff == NULL || currentsd == NULL) {
> printk(KERN_ERR "cciss: out of memory\n");
> goto out;
> diff -u -p a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> --- a/drivers/block/xen-blkfront.c 2011-11-13 11:07:22.680095573 +0100
> +++ b/drivers/block/xen-blkfront.c 2011-11-28 19:49:29.109460410 +0100
> @@ -156,7 +156,7 @@ static int xlbd_reserve_minors(unsigned
> if (end > nr_minors) {
> unsigned long *bitmap, *old;
>
> - bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
> + bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
> GFP_KERNEL);
> if (bitmap == NULL)
> return -ENOMEM;
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/

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