(old discussion, changing title)
Johan Hovold <[email protected]> writes:
> On Tue, Oct 24, 2023 at 05:07:38PM +0300, Kalle Valo wrote:
>
>> Johan Hovold <[email protected]> writes:
>>
>> > RCU lockdep reported suspicious RCU usage when accessing the temperature
>> > sensor. Inspection revealed that the DFS radar event code was also
>> > missing the required RCU read-side critical section marking.
>> >
>> > Johan
>> >
>> >
>> > Changes in v2
>> > - add the missing rcu_read_unlock() to an
>> > ath11k_wmi_pdev_temperature_event() error path as noticed by Jeff
>> >
>> >
>> > Johan Hovold (2):
>> > wifi: ath11k: fix temperature event locking
>> > wifi: ath11k: fix dfs radar event locking
>>
>> Thanks for the fixes. I really like using lockdep_assert_held() to
>> document if a function requires some lock held, is there anything
>> similar for RCU?
>
> Not really, but the checking is instead built into the primitives like
> rcu_dereference() and enabled whenever CONFIG_PROVE_RCU is set.
>
> For some special cases, we have open-coded checks like:
>
> RCU_LOCKDEP_WARN(!rcu_read_lock_held());
>
> which similarly depend on CONFIG_PROVE_RCU or simply
>
> WARN_ON_ONCE(!rcu_read_lock_held());
I just found out that sparse has __must_hold():
https://lore.kernel.org/linux-wireless/[email protected]/
That looks promising, should we start using that in ath11k and ath12k to
check our RCU usage?
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Hi Kalle,
On Sat, Jan 13, 2024 at 12:26:53PM +0200, Kalle Valo wrote:
> (old discussion, changing title)
>
> Johan Hovold <[email protected]> writes:
>
> > On Tue, Oct 24, 2023 at 05:07:38PM +0300, Kalle Valo wrote:
> >> Thanks for the fixes. I really like using lockdep_assert_held() to
> >> document if a function requires some lock held, is there anything
> >> similar for RCU?
> >
> > Not really, but the checking is instead built into the primitives like
> > rcu_dereference() and enabled whenever CONFIG_PROVE_RCU is set.
> >
> > For some special cases, we have open-coded checks like:
> >
> > RCU_LOCKDEP_WARN(!rcu_read_lock_held());
> >
> > which similarly depend on CONFIG_PROVE_RCU or simply
> >
> > WARN_ON_ONCE(!rcu_read_lock_held());
>
> I just found out that sparse has __must_hold():
>
> https://lore.kernel.org/linux-wireless/[email protected]/
>
> That looks promising, should we start using that in ath11k and ath12k to
> check our RCU usage?
I see that Johannes already commented on this in the thread above.
I'm pretty sure smatch can't be used for this.
Johan
On Mon, Jan 22, 2024 at 02:10:17PM +0100, Johan Hovold wrote:
> On Sat, Jan 13, 2024 at 12:26:53PM +0200, Kalle Valo wrote:
> > I just found out that sparse has __must_hold():
> >
> > https://lore.kernel.org/linux-wireless/[email protected]/
> >
> > That looks promising, should we start using that in ath11k and ath12k to
> > check our RCU usage?
>
> I see that Johannes already commented on this in the thread above.
>
> I'm pretty sure smatch can't be used for this.
I meant "sparse"...
Johan
Johan Hovold <[email protected]> writes:
> On Mon, Jan 22, 2024 at 02:10:17PM +0100, Johan Hovold wrote:
>> On Sat, Jan 13, 2024 at 12:26:53PM +0200, Kalle Valo wrote:
>
>> > I just found out that sparse has __must_hold():
>> >
>> > https://lore.kernel.org/linux-wireless/[email protected]/
>> >
>> > That looks promising, should we start using that in ath11k and ath12k to
>> > check our RCU usage?
>>
>> I see that Johannes already commented on this in the thread above.
>>
>> I'm pretty sure smatch can't be used for this.
>
> I meant "sparse"...
Yeah, that was a disappointment. I should have tested it first :)
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