linux-kernel - Re: [PATCH v2] nitro_enclaves: Fix implicit type conversion

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Message-ID: <65d5d6b8-03bc-772c-8d06-63989302e45c@amazon.com>
Date:   Tue, 2 Nov 2021 22:02:10 +0200
From:   "Paraschiv, Andra-Irina" <andraprs@...zon.com>
To:     Jiasheng Jiang <jiasheng@...as.ac.cn>
CC:     <linux-kernel@...r.kernel.org>, <lexnv@...zon.com>,
        <alcioa@...zon.com>, Greg KH <gregkh@...uxfoundation.org>,
        Kamal Mostafa <kamal@...onical.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        "Vitaly Kuznetsov" <vkuznets@...hat.com>,
        "ne-devel-upstream@...zon.com" <ne-devel-upstream@...zon.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH v2] nitro_enclaves: Fix implicit type conversion



On 29/10/2021 04:48, Jiasheng Jiang wrote:
> 
> The variable 'cpu' and 'cpu_sibling' are defined as unsigned int.
> However in the for_each_cpu, their values are assigned to -1.
> That doesn't make sense and in the cpumask_next() they are implicitly
> type conversed to int.
> It is universally accepted that the implicit type conversion is
> terrible.
> Also, having the good programming custom will set an example for
> others.
> Thus, it might be better to change the definition of 'cpu' and
> 'cpu_sibling' from unsigned int to int.
> 
> Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
> ---
>   drivers/virt/nitro_enclaves/ne_misc_dev.c | 14 +++++++-------
>   1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/virt/nitro_enclaves/ne_misc_dev.c b/drivers/virt/nitro_enclaves/ne_misc_dev.c
> index e21e1e8..2d80879 100644
> --- a/drivers/virt/nitro_enclaves/ne_misc_dev.c
> +++ b/drivers/virt/nitro_enclaves/ne_misc_dev.c
> @@ -168,9 +168,9 @@ static bool ne_check_enclaves_created(void)
>   static int ne_setup_cpu_pool(const char *ne_cpu_list)
>   {
>          int core_id = -1;
> -       unsigned int cpu = 0;
> +       int cpu = 0;
>          cpumask_var_t cpu_pool;
> -       unsigned int cpu_sibling = 0;
> +       int cpu_sibling = 0;
>          unsigned int i = 0;
>          int numa_node = -1;
>          int rc = -EINVAL;
> @@ -374,7 +374,7 @@ static int ne_setup_cpu_pool(const char *ne_cpu_list)
>    */
>   static void ne_teardown_cpu_pool(void)
>   {
> -       unsigned int cpu = 0;
> +       int cpu = 0;
>          unsigned int i = 0;
>          int rc = -EINVAL;
> 
> @@ -516,7 +516,7 @@ static int ne_get_unused_core_from_cpu_pool(void)
>   static int ne_set_enclave_threads_per_core(struct ne_enclave *ne_enclave,
>                                             int core_id, u32 vcpu_id)
>   {
> -       unsigned int cpu = 0;
> +       int cpu = 0;
> 
>          if (core_id < 0 && vcpu_id == 0) {
>                  dev_err_ratelimited(ne_misc_dev.this_device,
> @@ -562,7 +562,7 @@ static int ne_set_enclave_threads_per_core(struct ne_enclave *ne_enclave,
>   static int ne_get_cpu_from_cpu_pool(struct ne_enclave *ne_enclave, u32 *vcpu_id)
>   {
>          int core_id = -1;
> -       unsigned int cpu = 0;
> +       int cpu = 0;
>          unsigned int i = 0;
>          int rc = -EINVAL;
> 
> @@ -1017,7 +1017,7 @@ static int ne_start_enclave_ioctl(struct ne_enclave *ne_enclave,
>          struct ne_enclave_start_info *enclave_start_info)
>   {
>          struct ne_pci_dev_cmd_reply cmd_reply = {};
> -       unsigned int cpu = 0;
> +       int cpu = 0;
>          struct enclave_start_req enclave_start_req = {};
>          unsigned int i = 0;
>          struct pci_dev *pdev = ne_devs.ne_pci_dev->pdev;
> @@ -1360,7 +1360,7 @@ static void ne_enclave_remove_all_mem_region_entries(struct ne_enclave *ne_encla
>    */
>   static void ne_enclave_remove_all_vcpu_id_entries(struct ne_enclave *ne_enclave)
>   {
> -       unsigned int cpu = 0;
> +       int cpu = 0;
>          unsigned int i = 0;
> 
>          mutex_lock(&ne_cpu_pool.mutex);
> --
> 2.7.4
> 

Reviewed-by: Andra Paraschiv <andraprs@...zon.com>

As a follow-up, in general, when sending new versions of the patch(es) 
please also include the changelog after the "---" line. For example:

---
Changelog

v1 -> v2

* Change 1.
* Change 2.
...........


That helps with patch(es) changes tracking.

Thanks,
Andra



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