lkml.org 
[lkml]   [2021]   [Jun]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] locking/lockdep: unlikely bfs error check
Date
On 6/16/21 10:59 AM, Xiongwei Song wrote:
>
>> On Jun 16, 2021, at 10:48 PM, Waiman Long <llong@redhat.com> wrote:
>>
>> On 6/16/21 10:42 AM, Xiongwei Song wrote:
>>> From: Xiongwei Song <sxwjean@gmail.com>
>>>
>>> The error from graph walk is small probability event, so unlikely
>>> bfs_error can improve performance a little bit.
>>>
>>> Signed-off-by: Xiongwei Song <sxwjean@gmail.com>
>>> ---
>>> kernel/locking/lockdep.c | 12 ++++++------
>>> 1 file changed, 6 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
>>> index 074fd6418c20..af8c9203cd3e 100644
>>> --- a/kernel/locking/lockdep.c
>>> +++ b/kernel/locking/lockdep.c
>>> @@ -2646,7 +2646,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
>>> bfs_init_rootb(&this, prev);
>>> ret = __bfs_backwards(&this, &usage_mask, usage_accumulate, usage_skip, NULL);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -2664,7 +2664,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
>>> bfs_init_root(&that, next);
>>> ret = find_usage_forwards(&that, forward_mask, &target_entry1);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -2679,7 +2679,7 @@ static int check_irq_usage(struct task_struct *curr, struct held_lock *prev,
>>> backward_mask = original_mask(target_entry1->class->usage_mask);
>>> ret = find_usage_backwards(&this, backward_mask, &target_entry);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -2998,7 +2998,7 @@ check_prev_add(struct task_struct *curr, struct held_lock *prev,
>>> * Is the <prev> -> <next> link redundant?
>>> */
>>> ret = check_redundant(prev, next);
>>> - if (bfs_error(ret))
>>> + if (unlikely(bfs_error(ret)))
>>> return 0;
>>> else if (ret == BFS_RMATCH)
>>> return 2;
>>> @@ -3911,7 +3911,7 @@ check_usage_forwards(struct task_struct *curr, struct held_lock *this,
>>> bfs_init_root(&root, this);
>>> ret = find_usage_forwards(&root, usage_mask, &target_entry);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>>> @@ -3946,7 +3946,7 @@ check_usage_backwards(struct task_struct *curr, struct held_lock *this,
>>> bfs_init_rootb(&root, this);
>>> ret = find_usage_backwards(&root, usage_mask, &target_entry);
>>> - if (bfs_error(ret)) {
>>> + if (unlikely(bfs_error(ret))) {
>>> print_bfs_bug(ret);
>>> return 0;
>>> }
>> I think it is better to put the unlikely() directly into the bfs_error() inline function instead of sprinkling it all over the place.
> Sounds good. Thank you for the suggestion. I will update the patch.

Another nit. It is a bit odd that sent out two patches separately though
they do seem to have a bit of dependency. I think you should post them
as a 2-patch series.

Cheers,
Longman

\
 
 \ /
  Last update: 2021-06-16 17:12    [W:0.063 / U:0.212 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site