Calling 'list_splice' followed by 'INIT_LIST_HEAD' is equivalent to
'list_splice_init'.
This has been spotted with the following coccinelle script:
/////
@@
expression y,z;
@@
- list_splice(y,z);
- INIT_LIST_HEAD(y);
+ list_splice_init(y,z);
Signed-off-by: Christophe JAILLET <redacted>
---
net/rds/loop.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
@@ -167,8 +167,7 @@ void rds_loop_exit(void)/* avoid calling conn_destroy with irqs off */spin_lock_irq(&loop_conns_lock);-list_splice(&loop_conns,&tmp_list);-INIT_LIST_HEAD(&loop_conns);+list_splice_init(&loop_conns,&tmp_list);spin_unlock_irq(&loop_conns_lock);list_for_each_entry_safe(lc,_lc,&tmp_list,loop_node){
--
2.7.4
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From: Leon Romanovsky <leon@kernel.org> Date: 2016-09-04 12:21:01
On Sat, Sep 03, 2016 at 07:33:29AM +0200, Christophe JAILLET wrote:
Calling 'list_splice' followed by 'INIT_LIST_HEAD' is equivalent to
'list_splice_init'.
It is not 100% accurate
list_splice(y, z)
INIT_LIST_HEAD(y)
==>
if (!list_empty(y))
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
and not
if (!list_empty(y)) {
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
}
as list_splice_init will do.
quoted hunk
This has been spotted with the following coccinelle script:
/////
@@
expression y,z;
@@
- list_splice(y,z);
- INIT_LIST_HEAD(y);
+ list_splice_init(y,z);
Signed-off-by: Christophe JAILLET <redacted>
---
net/rds/loop.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
On Sat, Sep 03, 2016 at 07:33:29AM +0200, Christophe JAILLET wrote:
quoted
Calling 'list_splice' followed by 'INIT_LIST_HEAD' is equivalent to
'list_splice_init'.
It is not 100% accurate
list_splice(y, z)
INIT_LIST_HEAD(y)
==>
if (!list_empty(y))
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
and not
if (!list_empty(y)) {
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
}
as list_splice_init will do.
You are right but if you dig further you will see that calling INIT_LIST_HEAD on an empty list is a no-op (AFAIK).
And if this list was not already correctly initialized, then you would have some other troubles.
CJ
From: Leon Romanovsky <leon@kernel.org> Date: 2016-09-04 18:25:05
On Sun, Sep 04, 2016 at 05:57:20PM +0200, Christophe JAILLET wrote:
Le 04/09/2016 à 14:20, Leon Romanovsky a écrit :
quoted
On Sat, Sep 03, 2016 at 07:33:29AM +0200, Christophe JAILLET wrote:
quoted
Calling 'list_splice' followed by 'INIT_LIST_HEAD' is equivalent to
'list_splice_init'.
It is not 100% accurate
list_splice(y, z)
INIT_LIST_HEAD(y)
==>
if (!list_empty(y))
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
and not
if (!list_empty(y)) {
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
}
as list_splice_init will do.
You are right but if you dig further you will see that calling
INIT_LIST_HEAD on an empty list is a no-op (AFAIK).
And if this list was not already correctly initialized, then you would have
some other troubles.
Thank you for the suggestion,
It looks like the code after that can be skipped in case of loop_conns
list is empty, the tmp_list will be empty too.
174 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
175 WARN_ON(lc->conn->c_passive);
176 rds_conn_destroy(lc->conn);
177 }
On Sun, Sep 04, 2016 at 05:57:20PM +0200, Christophe JAILLET wrote:
quoted
Le 04/09/2016 à 14:20, Leon Romanovsky a écrit :
quoted
On Sat, Sep 03, 2016 at 07:33:29AM +0200, Christophe JAILLET wrote:
quoted
Calling 'list_splice' followed by 'INIT_LIST_HEAD' is equivalent to
'list_splice_init'.
It is not 100% accurate
list_splice(y, z)
INIT_LIST_HEAD(y)
==>
if (!list_empty(y))
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
and not
if (!list_empty(y)) {
__list_splice(y, z, z>next);
INIT_LIST_HEAD(y)
}
as list_splice_init will do.
You are right but if you dig further you will see that calling
INIT_LIST_HEAD on an empty list is a no-op (AFAIK).
And if this list was not already correctly initialized, then you would have
some other troubles.
Thank you for the suggestion,
It looks like the code after that can be skipped in case of loop_conns
list is empty, the tmp_list will be empty too.
174 list_for_each_entry_safe(lc, _lc, &tmp_list, loop_node) {
175 WARN_ON(lc->conn->c_passive);
176 rds_conn_destroy(lc->conn);
177 }
Thanks for trying. As already pointed, your change doesn't simplify
much rather change the behavior. The loop cursor already takes care
of list empty case. I don't see any reason to change that code.
Regards,
Santosh
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