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

[Srishti Sharma]

On Sat, Sep 30, 2017 at 11:51 AM, Julia Lawall <julia.lawall@xxxxxxx> wrote:
>
>
> On Sat, 30 Sep 2017, Srishti Sharma wrote:
>
>> 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,...)
>
> Yes.  You don't even need the e =.  As long as there is a call to
> container_of on a list_head * value, you can change it.

Okay, Thanks again :) , I'll make the changes and resend .

Regards,
Srishti
>
> julia
>
>>
>> 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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