Messages in this thread | | | Subject | Re: [PATCH] locking/lockdep: unlikely bfs error check | From | Xiongwei Song <> | Date | Wed, 16 Jun 2021 22:59:16 +0800 |
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> 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.
Regards, Xiongwei
> > Cheers, > Longman >
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