From: Jangwoong Kim <[email protected]>
We return 1, not the index of futex woken up.
Signed-off-by: Jangwoong Kim <[email protected]>
---
kernel/futex/waitwake.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
index 4ce0923f1ce3..d148e5d4956b 100644
--- a/kernel/futex/waitwake.c
+++ b/kernel/futex/waitwake.c
@@ -455,8 +455,8 @@ static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *wo
/*
* Even if something went wrong, if we find out that a futex
- * was woken, we don't return error and return this index to
- * userspace
+ * was woken, we don't return error and make userspace aware
+ * of this by returning 1.
*/
*woken = unqueue_multiple(vs, i);
if (*woken >= 0)
--
2.25.1
Hi Jangwoong,
Thanks for your patch! However...
Às 15:14 de 04/12/21, [email protected] escreveu:
> From: Jangwoong Kim <[email protected]>
>
> We return 1, not the index of futex woken up.
>
> Signed-off-by: Jangwoong Kim <[email protected]>
> ---
> kernel/futex/waitwake.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
> index 4ce0923f1ce3..d148e5d4956b 100644
> --- a/kernel/futex/waitwake.c
> +++ b/kernel/futex/waitwake.c
> @@ -455,8 +455,8 @@ static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *wo
>
> /*
> * Even if something went wrong, if we find out that a futex
> - * was woken, we don't return error and return this index to
> - * userspace
> + * was woken, we don't return error and make userspace aware
> + * of this by returning 1.
We return to userspace the value at *woken, so your fix is wrong. Have a
look at futex_wait_multiple():
ret = futex_wait_multiple_setup(vs, count, &hint);
if (ret) {
if (ret > 0) {
/* A futex was woken during setup */
ret = hint;
}
return ret;
}
When we return 1 at futex_wait_multiple_setup(), we end up returning the
hint/woken value to userspace.
Let me know if you have questions.
André
Hi André.
That patch was definitely wrong, I apologize.
However, since futex_wait_multiple_setup() sets the last index of
futex that was woken up,
shouldn't the comment be modified as below?
If so, I will resend a patch.
/*
- * Even if something went wrong, if we find out that a futex
- * was woken, we don't return error and return this index to
- * userspace
+ * Even if something went wrong, if we find out that any futex
+ * was woken, we don't return error and return the last index
+ * awoken to userspace
*/
*woken = unqueue_multiple(vs, i);
if (*woken >= 0)
I sent the patch because I thought this was important enough to be corrected.
Let me know If this is not crucial enough to be patched, so I won't
keep sending comment-fixing patches.
Thank you.
Jangwoong Kim.
2021년 12월 6일 (월) 오후 9:12, André Almeida <[email protected]>님이 작성:
>
> Hi Jangwoong,
>
> Thanks for your patch! However...
>
> Às 15:14 de 04/12/21, [email protected] escreveu:
> > From: Jangwoong Kim <[email protected]>
> >
> > We return 1, not the index of futex woken up.
> >
> > Signed-off-by: Jangwoong Kim <[email protected]>
> > ---
> > kernel/futex/waitwake.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
> > index 4ce0923f1ce3..d148e5d4956b 100644
> > --- a/kernel/futex/waitwake.c
> > +++ b/kernel/futex/waitwake.c
> > @@ -455,8 +455,8 @@ static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *wo
> >
> > /*
> > * Even if something went wrong, if we find out that a futex
> > - * was woken, we don't return error and return this index to
> > - * userspace
> > + * was woken, we don't return error and make userspace aware
> > + * of this by returning 1.
>
> We return to userspace the value at *woken, so your fix is wrong. Have a
> look at futex_wait_multiple():
>
> ret = futex_wait_multiple_setup(vs, count, &hint);
> if (ret) {
> if (ret > 0) {
> /* A futex was woken during setup */
> ret = hint;
> }
> return ret;
> }
>
> When we return 1 at futex_wait_multiple_setup(), we end up returning the
> hint/woken value to userspace.
>
> Let me know if you have questions.
>
> André
Hi Jangwoong,
Please don't top post when replying to emails in this list (read more
here: https://www.mediawiki.org/wiki/Mailing_list_etiquette)
Às 14:44 de 06/12/21, Jangwoong Kim escreveu:
> Hi André.
>
> That patch was definitely wrong, I apologize.
>
> However, since futex_wait_multiple_setup() sets the last index of
> futex that was woken up,
> shouldn't the comment be modified as below?
>
> If so, I will resend a patch.
>
> /*
> - * Even if something went wrong, if we find out that a futex
> - * was woken, we don't return error and return this index to
> - * userspace
> + * Even if something went wrong, if we find out that any futex
> + * was woken, we don't return error and return the last index
> + * awoken to userspace
Indeed, this is more correct. You can send a patch to clarify this comment.
> */
> *woken = unqueue_multiple(vs, i);
> if (*woken >= 0)
>
> I sent the patch because I thought this was important enough to be corrected.
>
> Let me know If this is not crucial enough to be patched, so I won't
> keep sending comment-fixing patches.
>
> Thank you.
> Jangwoong Kim.
>
> 2021년 12월 6일 (월) 오후 9:12, André Almeida <[email protected]>님이 작성:
>>
>> Hi Jangwoong,
>>
>> Thanks for your patch! However...
>>
>> Às 15:14 de 04/12/21, [email protected] escreveu:
>>> From: Jangwoong Kim <[email protected]>
>>>
>>> We return 1, not the index of futex woken up.
>>>
>>> Signed-off-by: Jangwoong Kim <[email protected]>
>>> ---
>>> kernel/futex/waitwake.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/kernel/futex/waitwake.c b/kernel/futex/waitwake.c
>>> index 4ce0923f1ce3..d148e5d4956b 100644
>>> --- a/kernel/futex/waitwake.c
>>> +++ b/kernel/futex/waitwake.c
>>> @@ -455,8 +455,8 @@ static int futex_wait_multiple_setup(struct futex_vector *vs, int count, int *wo
>>>
>>> /*
>>> * Even if something went wrong, if we find out that a futex
>>> - * was woken, we don't return error and return this index to
>>> - * userspace
>>> + * was woken, we don't return error and make userspace aware
>>> + * of this by returning 1.
>>
>> We return to userspace the value at *woken, so your fix is wrong. Have a
>> look at futex_wait_multiple():
>>
>> ret = futex_wait_multiple_setup(vs, count, &hint);
>> if (ret) {
>> if (ret > 0) {
>> /* A futex was woken during setup */
>> ret = hint;
>> }
>> return ret;
>> }
>>
>> When we return 1 at futex_wait_multiple_setup(), we end up returning the
>> hint/woken value to userspace.
>>
>> Let me know if you have questions.
>>
>> André