2016-04-20 04:17:33

by Davidlohr Bueso

Subject: [PATCH -tip v3 3/3] locking/pvqspinlock: Robustify init_qspinlock_stat()

locking/pvqspinlock: Robustify init_qspinlock_stat()

Specifically around the debugfs file creation calls,
I have no idea if they could ever possibly fail, but
this is core code (debug aside) so lets at least
check the return value and inform anything fishy.

Signed-off-by: Davidlohr Bueso <[email protected]>
---
kernel/locking/qspinlock_stat.h | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
index 72722334237a..22e025309845 100644
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -212,10 +212,8 @@ static int __init init_qspinlock_stat(void)
struct dentry *d_qstat = debugfs_create_dir("qlockstat", NULL);
int i;

- if (!d_qstat) {
- pr_warn("Could not create 'qlockstat' debugfs directory\n");
- return 0;
- }
+ if (!d_qstat)
+ goto out;

/*
* Create the debugfs files
@@ -225,12 +223,20 @@ static int __init init_qspinlock_stat(void)
* performance.
*/
for (i = 0; i < qstat_num; i++)
- debugfs_create_file(qstat_names[i], 0400, d_qstat,
- (void *)(long)i, &fops_qstat);
+ if (!debugfs_create_file(qstat_names[i], 0400, d_qstat,
+ (void *)(long)i, &fops_qstat))
+ goto fail_undo;
+
+ if (!debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat,
+ (void *)(long)qstat_reset_cnts, &fops_qstat))
+ goto fail_undo;

- debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat,
- (void *)(long)qstat_reset_cnts, &fops_qstat);
return 0;
+fail_undo:
+ debugfs_remove_recursive(d_qstat);
+out:
+ pr_warn("Could not create 'qlockstat' debugfs entries\n");
+ return -ENOMEM;
}
fs_initcall(init_qspinlock_stat);

--
2.8.1

2016-04-20 20:07:01

by Waiman Long

Subject: Re: [PATCH -tip v3 3/3] locking/pvqspinlock: Robustify init_qspinlock_stat()

On 04/20/2016 12:17 AM, Davidlohr Bueso wrote:
> locking/pvqspinlock: Robustify init_qspinlock_stat()
>
> Specifically around the debugfs file creation calls,
> I have no idea if they could ever possibly fail, but
> this is core code (debug aside) so lets at least
> check the return value and inform anything fishy.
>
> Signed-off-by: Davidlohr Bueso <[email protected]>
> ---
> kernel/locking/qspinlock_stat.h | 22 ++++++++++++++--------
> 1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/locking/qspinlock_stat.h
> b/kernel/locking/qspinlock_stat.h
> index 72722334237a..22e025309845 100644
> --- a/kernel/locking/qspinlock_stat.h
> +++ b/kernel/locking/qspinlock_stat.h
> @@ -212,10 +212,8 @@ static int __init init_qspinlock_stat(void)
> struct dentry *d_qstat = debugfs_create_dir("qlockstat", NULL);
> int i;
>
> - if (!d_qstat) {
> - pr_warn("Could not create 'qlockstat' debugfs directory\n");
> - return 0;
> - }
> + if (!d_qstat)
> + goto out;
>
> /*
> * Create the debugfs files
> @@ -225,12 +223,20 @@ static int __init init_qspinlock_stat(void)
> * performance.
> */
> for (i = 0; i < qstat_num; i++)
> - debugfs_create_file(qstat_names[i], 0400, d_qstat,
> - (void *)(long)i, &fops_qstat);
> + if (!debugfs_create_file(qstat_names[i], 0400, d_qstat,
> + (void *)(long)i, &fops_qstat))
> + goto fail_undo;
> +
> + if (!debugfs_create_file(qstat_names[qstat_reset_cnts], 0200,
> d_qstat,
> + (void *)(long)qstat_reset_cnts, &fops_qstat))
> + goto fail_undo;
>
> - debugfs_create_file(qstat_names[qstat_reset_cnts], 0200, d_qstat,
> - (void *)(long)qstat_reset_cnts, &fops_qstat);
> return 0;
> +fail_undo:
> + debugfs_remove_recursive(d_qstat);
> +out:
> + pr_warn("Could not create 'qlockstat' debugfs entries\n");
> + return -ENOMEM;
> }
> fs_initcall(init_qspinlock_stat);
>

Reviewed-by: Waiman Long <[email protected]>