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nvmet-fc: use zero-sized array and struct_size() in kzalloc()

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Update the code to use a zero-sized array instead of a pointer in
structure nvmet_fc_tgt_queue and use struct_size() in kzalloc().

Notice that 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 foo {
	int stuff;
	struct boo entry[];
};

instance = kzalloc(sizeof(struct foo) + sizeof(struct boo) * count, 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, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Gustavo A. R. Silva 2019-02-23 12:51:08 -06:00 committed by Christoph Hellwig
parent cfe03c2ec4
commit 6b80f1d2cc
1 changed files with 2 additions and 5 deletions
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7
drivers/nvme/target/fc.c
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@ -128,12 +128,12 @@ struct nvmet_fc_tgt_queue {
struct nvmet_cq nvme_cq;
struct nvmet_sq nvme_sq;
struct nvmet_fc_tgt_assoc *assoc;
struct nvmet_fc_fcp_iod *fod; /* array of fcp_iods */
struct list_head fod_list;
struct list_head pending_cmd_list;
struct list_head avail_defer_list;
struct workqueue_struct *work_q;
struct kref ref;
struct nvmet_fc_fcp_iod fod[]; /* array of fcp_iods */
} __aligned(sizeof(unsigned long long));
struct nvmet_fc_tgt_assoc {
@ -588,9 +588,7 @@ nvmet_fc_alloc_target_queue(struct nvmet_fc_tgt_assoc *assoc,
if (qid > NVMET_NR_QUEUES)
return NULL;
queue = kzalloc((sizeof(*queue) +
(sizeof(struct nvmet_fc_fcp_iod) * sqsize)),
GFP_KERNEL);
queue = kzalloc(struct_size(queue, fod, sqsize), GFP_KERNEL);
if (!queue)
return NULL;
@ -603,7 +601,6 @@ nvmet_fc_alloc_target_queue(struct nvmet_fc_tgt_assoc *assoc,
if (!queue->work_q)
goto out_a_put;
queue->fod = (struct nvmet_fc_fcp_iod *)&queue[1];
queue->qid = qid;
queue->sqsize = sqsize;
queue->assoc = assoc;