Re: [Outreachy kernel] [PATCH] Staging: rtl8188eu: core: Use list_entry instead of container_of

[Srishti Sharma]

On Sat, Sep 30, 2017 at 11:36 AM, Julia Lawall <julia.lawall@xxxxxxx> wrote:
>
>
> On Sat, 30 Sep 2017, Srishti Sharma wrote:
>
>> On Sat, Sep 30, 2017 at 10:35 AM, Julia Lawall <julia.lawall@xxxxxxx> wrote:
>> >
>> >
>> > On Sat, 30 Sep 2017, Srishti Sharma wrote:
>> >
>> >> For variables of the type struct list_head* use list_entry to access
>> >> the current list element instead of using container_of.
>> >> Done using the following semantic patch by coccinelle.
>> >>
>> >> @r@
>> >> identifier e;
>> >> struct list_head* l;
>> >> @@
>> >>
>> >> <... when != l == NULL
>> >> l;
>> >> ...>
>> > I don't see what is the goal of the above code.  The list_head variable is
>> > not going to be in a statement by itself.  There is also no need to check
>> > for l being NULL.  If it is NULL, the original code is incorrect too.
>>
>> Since only those container_of are to replaced with list_entry which
>> have a variable of type list_head*  , I wanted to check if it occurs
>> anywhere before
>> container_of ,
>
> Why?  If it is a list, then it seems appropriate to access it using
> list_head.
>
>> which it only does in it's declaration , because it
>> can't be in any
>> statement by itself . I think it will be better to write .
>>
>> @r@
>> identifier e;
>> struct list_head* l;
>> @@
>>
>> <...
>> container_of(l,...);
>> ...>
>
> This doesn't ensure that there is a preceding container_of, if that is
> what you are trying to do.  The problem is that <... P ...> finds 0 or
> more occurrences of pattern P, not 1 or more occurrences.  1 or more
> occurrences is <+... P ...+>.  But it would be simpler if you want an
> occurrence of container_of before the thing you are transforming to put
>
> container_of(l,...);
> ...
> e = ...
>
> But this doesn't make sense either, partly because the preceding
> container_of is just not needed, and also because a container_of would not
> be in a statement by itself.  In Coccinelle, when you put a ; after
> something is means that the thing is a complete statement, not just the
> end half of a statement.

So , I guess we can simply write.

e =
-container_of
+list_entry
     (l,...)

Regards,
Srishti

>
> julia
>
>> e =
>> -container_of
>> +list_entry
>>      (
>>       ....)
>>
>> >> (
>> >> e =
>> >> -container_of
>> >> +list_entry
>> >>      (
>> >>       ...)
>> >> )
>> >
>> > Here you don't need the outer ( ).  This makes a disjunction with only
>> > one choice.  Since there is only one choice, you don't need the
>> > disjunction.
>>
>> Thanks a lot , for pointing out the errors .
>>
>> Regards,
>> Srishti
>> > julia
>> >
>> >> Signed-off-by: Srishti Sharma <srishtishar@xxxxxxxxx>
>> >> ---
>> >>  drivers/staging/rtl8188eu/core/rtw_sta_mgt.c | 12 ++++++------
>> >>  1 file changed, 6 insertions(+), 6 deletions(-)
>> >>
>> >> diff --git a/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c b/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c
>> >> index 22cf362..f9df4ac 100644
>> >> --- a/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c
>> >> +++ b/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c
>> >> @@ -152,8 +152,8 @@ u32       _rtw_free_sta_priv(struct       sta_priv *pstapriv)
>> >>                       while (phead != plist) {
>> >>                               int i;
>> >>
>> >> -                             psta = container_of(plist, struct sta_info,
>> >> -                                                 hash_list);
>> >> +                             psta = list_entry(plist, struct sta_info,
>> >> +                                               hash_list);
>> >>                               plist = plist->next;
>> >>
>> >>                               for (i = 0; i < 16; i++) {
>> >> @@ -323,7 +323,7 @@ u32       rtw_free_stainfo(struct adapter *padapter, struct sta_info *psta)
>> >>               plist = phead->next;
>> >>
>> >>               while (!list_empty(phead)) {
>> >> -                     prframe = container_of(plist, struct recv_frame, list);
>> >> +                     prframe = list_entry(plist, struct recv_frame, list);
>> >>
>> >>                       plist = plist->next;
>> >>
>> >> @@ -399,7 +399,7 @@ void rtw_free_all_stainfo(struct adapter *padapter)
>> >>               plist = phead->next;
>> >>
>> >>               while (phead != plist) {
>> >> -                     psta = container_of(plist, struct sta_info, hash_list);
>> >> +                     psta = list_entry(plist, struct sta_info, hash_list);
>> >>
>> >>                       plist = plist->next;
>> >>
>> >> @@ -435,7 +435,7 @@ struct sta_info *rtw_get_stainfo(struct sta_priv *pstapriv, u8 *hwaddr)
>> >>       plist = phead->next;
>> >>
>> >>       while (phead != plist) {
>> >> -             psta = container_of(plist, struct sta_info, hash_list);
>> >> +             psta = list_entry(plist, struct sta_info, hash_list);
>> >>
>> >>               if ((!memcmp(psta->hwaddr, addr, ETH_ALEN)) == true) {
>> >>                       /*  if found the matched address */
>> >> @@ -493,7 +493,7 @@ u8 rtw_access_ctrl(struct adapter *padapter, u8 *mac_addr)
>> >>       phead = get_list_head(pacl_node_q);
>> >>       plist = phead->next;
>> >>       while (phead != plist) {
>> >> -             paclnode = container_of(plist, struct rtw_wlan_acl_node, list);
>> >> +             paclnode = list_entry(plist, struct rtw_wlan_acl_node, list);
>> >>               plist = plist->next;
>> >>
>> >>               if (!memcmp(paclnode->addr, mac_addr, ETH_ALEN)) {
>> >> --
>> >> 2.7.4
>> >>
>> >> --
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>>