* [PATCH] dm raid1: Use struct_size() in kzalloc()
@ 2019-08-06 0:18 Gustavo A. R. Silva
2019-08-06 12:45 ` Markus Elfring
0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2019-08-06 0:18 UTC (permalink / raw)
To: Alasdair Kergon, Mike Snitzer; +Cc: dm-devel, linux-kernel, Gustavo A. R. Silva
One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:
struct mirror_set {
...
struct mirror mirror[0];
};
size = sizeof(struct mirror_set) + count * sizeof(struct mirror);
instance = kzalloc(size, GFP_KERNEL)
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
instance = kzalloc(struct_size(instance, mirror, count), GFP_KERNEL)
Notice that, in this case, variable len is not necessary, hence it
is removed.
This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/md/dm-raid1.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 5a51151f680d..f7226ab57fc8 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -878,12 +878,9 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
struct dm_target *ti,
struct dm_dirty_log *dl)
{
- size_t len;
struct mirror_set *ms = NULL;
- len = sizeof(*ms) + (sizeof(ms->mirror[0]) * nr_mirrors);
-
- ms = kzalloc(len, GFP_KERNEL);
+ ms = kzalloc(struct_size(ms, mirror, nr_mirrors), GFP_KERNEL);
if (!ms) {
ti->error = "Cannot allocate mirror context";
return NULL;
--
2.22.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] dm raid1: Use struct_size() in kzalloc()
2019-08-06 0:18 [PATCH] dm raid1: Use struct_size() in kzalloc() Gustavo A. R. Silva
@ 2019-08-06 12:45 ` Markus Elfring
0 siblings, 0 replies; 2+ messages in thread
From: Markus Elfring @ 2019-08-06 12:45 UTC (permalink / raw)
To: Gustavo A. R. Silva, Alasdair Kergon, Mike Snitzer, dm-devel
Cc: kernel-janitors, linux-kernel, Colin Ian King
> +++ b/drivers/md/dm-raid1.c
> @@ -878,12 +878,9 @@ static struct mirror_set *alloc_context(unsigned int nr_mirrors,
> struct dm_target *ti,
> struct dm_dirty_log *dl)
> {
> - size_t len;
> struct mirror_set *ms = NULL;
…
How do you think about to replace the initialisation “NULL” by the desired function call?
Regards,
Markus
^ permalink raw reply [flat|nested] 2+ messages in thread
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