Re: [PATCH 4/8] staging: erofs: cleanup z_erofs_vle_work_{lookup, register}

Gao Xiang
2018-08-13T12:39:22Z

Hi Dan,

On 2018/8/13 20:00, Dan Carpenter wrote:
> On Sun, Aug 12, 2018 at 10:01:46PM +0800, Chao Yu wrote:
>> From: Gao Xiang <gaoxiang25@huawei.com>
>>
>> This patch introduces 'struct z_erofs_vle_work_finder' to clean up
>> arguments of z_erofs_vle_work_lookup and z_erofs_vle_work_register.
>>
>> Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
>> Reviewed-by: Chao Yu <yuchao0@huawei.com>
>> Signed-off-by: Chao Yu <yuchao0@huawei.com>
>> ---
>> drivers/staging/erofs/unzip_vle.c | 89 ++++++++++++++++---------------
>> 1 file changed, 47 insertions(+), 42 deletions(-)
>>
>> diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
>> index b2e05e2b4116..5032b3b05de1 100644
>> --- a/drivers/staging/erofs/unzip_vle.c
>> +++ b/drivers/staging/erofs/unzip_vle.c
>> @@ -271,36 +271,42 @@ static inline bool try_to_claim_workgroup(
>> return true; /* lucky, I am the followee :) */
>> }
>>
>> +struct z_erofs_vle_work_finder {
>> + struct super_block *sb;
>> + pgoff_t idx;
>> + unsigned pageofs;
>> +
>> + struct z_erofs_vle_workgroup **grp_ret;
>> + enum z_erofs_vle_work_role *role;
>> + z_erofs_vle_owned_workgrp_t *owned_head;
>> + bool *hosted;
>> +};
>> +
>> static struct z_erofs_vle_work *
>> -z_erofs_vle_work_lookup(struct super_block *sb,
>> - pgoff_t idx, unsigned pageofs,
>> - struct z_erofs_vle_workgroup **grp_ret,
>> - enum z_erofs_vle_work_role *role,
>> - z_erofs_vle_owned_workgrp_t *owned_head,
>> - bool *hosted)
>> +z_erofs_vle_work_lookup(const struct z_erofs_vle_work_finder *f)
>> {
>> bool tag, primary;
>> struct erofs_workgroup *egrp;
>> struct z_erofs_vle_workgroup *grp;
>> struct z_erofs_vle_work *work;
>>
>> - egrp = erofs_find_workgroup(sb, idx, &tag);
>> + egrp = erofs_find_workgroup(f->sb, f->idx, &tag);
>> if (egrp == NULL) {
>> - *grp_ret = NULL;
>> + *f->grp_ret = NULL;
>
> All these pointers to pointer seem a bit messy. Just do this:
>
> struct z_erofs_vle_workgroup *grp;
>
> Then replace "grp" in z_erofs_vle_work_iter_begin() with finder.grp;
>

I wrote this because I am not sure of all compiler behaviors.

Notice that the struct `struct z_erofs_vle_work_finder' has been all marked as const.

If I use `struct z_erofs_vle_workgroup *grp;' and drop the `const' decorator,
compilers could do some re-read operations bacause its value could potentially change by its caller at the same time.

Thanks,
Gao Xiang

> regards,
> dan carpenter
>