From: Peter Zijlstra <[email protected]>
commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
Both Geert and DaveJ reported that the recent futex commit:
c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
introduced a problem with setting OWNER_DEAD. We set the bit on an
uninitialized variable and then entirely optimize it away as a
dead-store.
Move the setting of the bit to where it is more useful.
Reported-by: Geert Uytterhoeven <[email protected]>
Reported-by: Dave Jones <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Zheng Yejian <[email protected]>
---
kernel/futex.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index b65dbb5d60bb..604d1cb9839d 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2424,9 +2424,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
int err = 0;
oldowner = pi_state->owner;
- /* Owner died? */
- if (!pi_state->owner)
- newtid |= FUTEX_OWNER_DIED;
/*
* We are here because either:
@@ -2484,6 +2481,9 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
}
newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
+ /* Owner died? */
+ if (!pi_state->owner)
+ newtid |= FUTEX_OWNER_DIED;
if (get_futex_value_locked(&uval, uaddr))
goto handle_fault;
--
2.25.4
On Tue, 23 Feb 2021, Zheng Yejian wrote:
> From: Peter Zijlstra <[email protected]>
>
> commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
>
> Both Geert and DaveJ reported that the recent futex commit:
>
> c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
>
> introduced a problem with setting OWNER_DEAD. We set the bit on an
> uninitialized variable and then entirely optimize it away as a
> dead-store.
>
> Move the setting of the bit to where it is more useful.
>
> Reported-by: Geert Uytterhoeven <[email protected]>
> Reported-by: Dave Jones <[email protected]>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: Paul E. McKenney <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> Link: http://lkml.kernel.org/r/[email protected]
> Signed-off-by: Ingo Molnar <[email protected]>
> Signed-off-by: Zheng Yejian <[email protected]>
Why have you dropped my Reviewed-by?
> ---
> kernel/futex.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/futex.c b/kernel/futex.c
> index b65dbb5d60bb..604d1cb9839d 100644
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -2424,9 +2424,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
> int err = 0;
>
> oldowner = pi_state->owner;
> - /* Owner died? */
> - if (!pi_state->owner)
> - newtid |= FUTEX_OWNER_DIED;
>
> /*
> * We are here because either:
> @@ -2484,6 +2481,9 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
> }
>
> newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
> + /* Owner died? */
> + if (!pi_state->owner)
> + newtid |= FUTEX_OWNER_DIED;
>
> if (get_futex_value_locked(&uval, uaddr))
> goto handle_fault;
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
On 2021/2/24 19:19, Lee Jones wrote:
> On Tue, 23 Feb 2021, Zheng Yejian wrote:
>
>> From: Peter Zijlstra <[email protected]>
>>
>> commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
>>
>> Both Geert and DaveJ reported that the recent futex commit:
>>
>> c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
>>
>> introduced a problem with setting OWNER_DEAD. We set the bit on an
>> uninitialized variable and then entirely optimize it away as a
>> dead-store.
>>
>> Move the setting of the bit to where it is more useful.
>>
>> Reported-by: Geert Uytterhoeven <[email protected]>
>> Reported-by: Dave Jones <[email protected]>
>> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
>> Cc: Andrew Morton <[email protected]>
>> Cc: Linus Torvalds <[email protected]>
>> Cc: Paul E. McKenney <[email protected]>
>> Cc: Peter Zijlstra <[email protected]>
>> Cc: Thomas Gleixner <[email protected]>
>> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
>> Link: http://lkml.kernel.org/r/[email protected]
>> Signed-off-by: Ingo Molnar <[email protected]>
>> Signed-off-by: Zheng Yejian <[email protected]>
>
> Why have you dropped my Reviewed-by?
>
Really sorry. I thought that a changed patchset needs another review.
Then I do need to append your Reviewed-by and send a "V2" patchset, Do I?
>> ---
>> kernel/futex.c | 6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/kernel/futex.c b/kernel/futex.c
>> index b65dbb5d60bb..604d1cb9839d 100644
>> --- a/kernel/futex.c
>> +++ b/kernel/futex.c
>> @@ -2424,9 +2424,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
>> int err = 0;
>>
>> oldowner = pi_state->owner;
>> - /* Owner died? */
>> - if (!pi_state->owner)
>> - newtid |= FUTEX_OWNER_DIED;
>>
>> /*
>> * We are here because either:
>> @@ -2484,6 +2481,9 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
>> }
>>
>> newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
>> + /* Owner died? */
>> + if (!pi_state->owner)
>> + newtid |= FUTEX_OWNER_DIED;
>>
>> if (get_futex_value_locked(&uval, uaddr))
>> goto handle_fault;
>
On Thu, 25 Feb 2021, Zhengyejian (Zetta) wrote:
>
>
> On 2021/2/24 19:19, Lee Jones wrote:
> > On Tue, 23 Feb 2021, Zheng Yejian wrote:
> >
> > > From: Peter Zijlstra <[email protected]>
> > >
> > > commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
> > >
> > > Both Geert and DaveJ reported that the recent futex commit:
> > >
> > > c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> > >
> > > introduced a problem with setting OWNER_DEAD. We set the bit on an
> > > uninitialized variable and then entirely optimize it away as a
> > > dead-store.
> > >
> > > Move the setting of the bit to where it is more useful.
> > >
> > > Reported-by: Geert Uytterhoeven <[email protected]>
> > > Reported-by: Dave Jones <[email protected]>
> > > Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
> > > Cc: Andrew Morton <[email protected]>
> > > Cc: Linus Torvalds <[email protected]>
> > > Cc: Paul E. McKenney <[email protected]>
> > > Cc: Peter Zijlstra <[email protected]>
> > > Cc: Thomas Gleixner <[email protected]>
> > > Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> > > Link: http://lkml.kernel.org/r/[email protected]
> > > Signed-off-by: Ingo Molnar <[email protected]>
> > > Signed-off-by: Zheng Yejian <[email protected]>
> >
> > Why have you dropped my Reviewed-by?
> >
> Really sorry. I thought that a changed patchset needs another review.
> Then I do need to append your Reviewed-by and send a "V2" patchset, Do I?
No need. I won't hold up merging just for that.
Just bear in mind that you should apply and carry forward *-by tags
unless there have been significant/functional changes.
Reviewed-by: Lee Jones <[email protected]>
> > > ---
> > > kernel/futex.c | 6 +++---
> > > 1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/kernel/futex.c b/kernel/futex.c
> > > index b65dbb5d60bb..604d1cb9839d 100644
> > > --- a/kernel/futex.c
> > > +++ b/kernel/futex.c
> > > @@ -2424,9 +2424,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
> > > int err = 0;
> > > oldowner = pi_state->owner;
> > > - /* Owner died? */
> > > - if (!pi_state->owner)
> > > - newtid |= FUTEX_OWNER_DIED;
> > > /*
> > > * We are here because either:
> > > @@ -2484,6 +2481,9 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
> > > }
> > > newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
> > > + /* Owner died? */
> > > + if (!pi_state->owner)
> > > + newtid |= FUTEX_OWNER_DIED;
> > > if (get_futex_value_locked(&uval, uaddr))
> > > goto handle_fault;
> >
--
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog
On 2021/2/25 16:09, Lee Jones wrote:
> On Thu, 25 Feb 2021, Zhengyejian (Zetta) wrote:
>
>>
>>
>> On 2021/2/24 19:19, Lee Jones wrote:
>>> On Tue, 23 Feb 2021, Zheng Yejian wrote:
>>>
>>>> From: Peter Zijlstra <[email protected]>
>>>>
>>>> commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
>>>>
>>>> Both Geert and DaveJ reported that the recent futex commit:
>>>>
>>>> c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
>>>>
>>>> introduced a problem with setting OWNER_DEAD. We set the bit on an
>>>> uninitialized variable and then entirely optimize it away as a
>>>> dead-store.
>>>>
>>>> Move the setting of the bit to where it is more useful.
>>>>
>>>> Reported-by: Geert Uytterhoeven <[email protected]>
>>>> Reported-by: Dave Jones <[email protected]>
>>>> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
>>>> Cc: Andrew Morton <[email protected]>
>>>> Cc: Linus Torvalds <[email protected]>
>>>> Cc: Paul E. McKenney <[email protected]>
>>>> Cc: Peter Zijlstra <[email protected]>
>>>> Cc: Thomas Gleixner <[email protected]>
>>>> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
>>>> Link: http://lkml.kernel.org/r/[email protected]
>>>> Signed-off-by: Ingo Molnar <[email protected]>
>>>> Signed-off-by: Zheng Yejian <[email protected]>
>>>
>>> Why have you dropped my Reviewed-by?
>>>
>> Really sorry. I thought that a changed patchset needs another review.
>> Then I do need to append your Reviewed-by and send a "V2" patchset, Do I?
>
> No need. I won't hold up merging just for that.
>
> Just bear in mind that you should apply and carry forward *-by tags
> unless there have been significant/functional changes.
>
> Reviewed-by: Lee Jones <[email protected]>
>
I get it, thanks.
>>>> ---
>>>> kernel/futex.c | 6 +++---
>>>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/kernel/futex.c b/kernel/futex.c
>>>> index b65dbb5d60bb..604d1cb9839d 100644
>>>> --- a/kernel/futex.c
>>>> +++ b/kernel/futex.c
>>>> @@ -2424,9 +2424,6 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
>>>> int err = 0;
>>>> oldowner = pi_state->owner;
>>>> - /* Owner died? */
>>>> - if (!pi_state->owner)
>>>> - newtid |= FUTEX_OWNER_DIED;
>>>> /*
>>>> * We are here because either:
>>>> @@ -2484,6 +2481,9 @@ static int __fixup_pi_state_owner(u32 __user *uaddr, struct futex_q *q,
>>>> }
>>>> newtid = task_pid_vnr(newowner) | FUTEX_WAITERS;
>>>> + /* Owner died? */
>>>> + if (!pi_state->owner)
>>>> + newtid |= FUTEX_OWNER_DIED;
>>>> if (get_futex_value_locked(&uval, uaddr))
>>>> goto handle_fault;
>>>
>
On Tue, Feb 23, 2021 at 10:41:51PM +0800, Zheng Yejian wrote:
> From: Peter Zijlstra <[email protected]>
>
> commit a97cb0e7b3f4c6297fd857055ae8e895f402f501 upstream.
>
> Both Geert and DaveJ reported that the recent futex commit:
>
> c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
>
> introduced a problem with setting OWNER_DEAD. We set the bit on an
> uninitialized variable and then entirely optimize it away as a
> dead-store.
>
> Move the setting of the bit to where it is more useful.
>
> Reported-by: Geert Uytterhoeven <[email protected]>
> Reported-by: Dave Jones <[email protected]>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
> Cc: Andrew Morton <[email protected]>
> Cc: Linus Torvalds <[email protected]>
> Cc: Paul E. McKenney <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Fixes: c1e2f0eaf015 ("futex: Avoid violating the 10th rule of futex")
> Link: http://lkml.kernel.org/r/[email protected]
> Signed-off-by: Ingo Molnar <[email protected]>
> Signed-off-by: Zheng Yejian <[email protected]>
> ---
> kernel/futex.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
Now queued up, thanks.
greg k-h