Re: [PATCH] nvmet-fc: use zero-sized array and struct_size() in kzalloc()
From: Gustavo A. R. Silva
Date: Sat Feb 23 2019 - 15:28:30 EST
Hey Joe,
On 2/23/19 2:05 PM, Joe Perches wrote:
> On Sat, 2019-02-23 at 12:51 -0600, Gustavo A. R. Silva wrote:
>> 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().
> []
>> This code was detected with the help of Coccinelle.
>
> Really?
> Impressive script that found this one.
>
See my comments below.
>> diff --git a/drivers/nvme/target/fc.c b/drivers/nvme/target/fc.c
> []
>> @@ -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));
>
> Moving a pointer from the middle of a struct to
> the end seems unusual for coccinelle.
>
>
Notice that the commit log says "detected", which does not imply
the script made the transformation by itself. :)
And all the script detected was this piece of code:
queue = kzalloc((sizeof(*queue) +
(sizeof(struct nvmet_fc_fcp_iod) * sqsize)),
GFP_KERNEL);
Thanks
--
Gustavo