* [PATCH] PM: opp: Fix NULL pointer exception on a v2 table combined with v1 opps
@ 2022-04-01 12:03 Krzysztof Kozlowski
2022-04-04 6:26 ` Viresh Kumar
0 siblings, 1 reply; 4+ messages in thread
From: Krzysztof Kozlowski @ 2022-04-01 12:03 UTC (permalink / raw)
To: Viresh Kumar, Nishanth Menon, Stephen Boyd, Dmitry Osipenko,
linux-pm, linux-kernel
Cc: Krzysztof Kozlowski
dev_pm_opp_add() adds a v1 OPP. If the Devicetree contains an OPP v2
table with required-opps, but the driver uses dev_pm_opp_add(), the
table might have required_opp_count!=0 but the opp->required_opps will
be NULL. This leads to NULL pointer exception, e.g. with ufs-qcom.c
driver and v2 OPP table in DTS:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
...
Call trace:
_required_opps_available+0x20/0x80
_opp_add_v1+0xa8/0x110
dev_pm_opp_add+0x54/0xcc
ufshcd_async_scan+0x190/0x31c
async_run_entry_fn+0x38/0x144
Fixes: cf65948d62c6 ("opp: Filter out OPPs based on availability of a required-OPP")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
drivers/opp/core.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 740407252298..d21b7e7e3f9f 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -1760,7 +1760,9 @@ int _opp_add(struct device *dev, struct dev_pm_opp *new_opp,
if (lazy_linking_pending(opp_table))
return 0;
- _required_opps_available(new_opp, opp_table->required_opp_count);
+ /* No required_opps for v1 bindings OPP */
+ if (new_opp->required_opps)
+ _required_opps_available(new_opp, opp_table->required_opp_count);
return 0;
}
--
2.32.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] PM: opp: Fix NULL pointer exception on a v2 table combined with v1 opps
2022-04-01 12:03 [PATCH] PM: opp: Fix NULL pointer exception on a v2 table combined with v1 opps Krzysztof Kozlowski
@ 2022-04-04 6:26 ` Viresh Kumar
2022-04-04 6:28 ` Krzysztof Kozlowski
0 siblings, 1 reply; 4+ messages in thread
From: Viresh Kumar @ 2022-04-04 6:26 UTC (permalink / raw)
To: Krzysztof Kozlowski
Cc: Viresh Kumar, Nishanth Menon, Stephen Boyd, Dmitry Osipenko,
linux-pm, linux-kernel
On 01-04-22, 14:03, Krzysztof Kozlowski wrote:
> dev_pm_opp_add() adds a v1 OPP. If the Devicetree contains an OPP v2
> table with required-opps, but the driver uses dev_pm_opp_add(), the
> table might have required_opp_count!=0 but the opp->required_opps will
> be NULL.
This use-case isn't supported currently, as either all OPPs should
have required-opp or none. This kind of scenario may end up breaking
at other places later on, as I have designed this stuff with the
above assumption.
--
viresh
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] PM: opp: Fix NULL pointer exception on a v2 table combined with v1 opps
2022-04-04 6:26 ` Viresh Kumar
@ 2022-04-04 6:28 ` Krzysztof Kozlowski
2022-04-04 6:31 ` Viresh Kumar
0 siblings, 1 reply; 4+ messages in thread
From: Krzysztof Kozlowski @ 2022-04-04 6:28 UTC (permalink / raw)
To: Viresh Kumar
Cc: Viresh Kumar, Nishanth Menon, Stephen Boyd, Dmitry Osipenko,
linux-pm, linux-kernel
On 04/04/2022 08:26, Viresh Kumar wrote:
> On 01-04-22, 14:03, Krzysztof Kozlowski wrote:
>> dev_pm_opp_add() adds a v1 OPP. If the Devicetree contains an OPP v2
>> table with required-opps, but the driver uses dev_pm_opp_add(), the
>> table might have required_opp_count!=0 but the opp->required_opps will
>> be NULL.
>
> This use-case isn't supported currently, as either all OPPs should
> have required-opp or none. This kind of scenario may end up breaking
> at other places later on, as I have designed this stuff with the
> above assumption.
I understand this is not a proper use case, but it is easy to trigger
(UFS driver adds opps manually, DTS also adds one). Maybe you prefer to
handle it differently - exit with ERRNO? Because NULL pointer exception
in case of proper, but unexpected DTB is not a good way to handle it.
Best regards,
Krzysztof
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] PM: opp: Fix NULL pointer exception on a v2 table combined with v1 opps
2022-04-04 6:28 ` Krzysztof Kozlowski
@ 2022-04-04 6:31 ` Viresh Kumar
0 siblings, 0 replies; 4+ messages in thread
From: Viresh Kumar @ 2022-04-04 6:31 UTC (permalink / raw)
To: Krzysztof Kozlowski
Cc: Viresh Kumar, Nishanth Menon, Stephen Boyd, Dmitry Osipenko,
linux-pm, linux-kernel
On 04-04-22, 08:28, Krzysztof Kozlowski wrote:
> I understand this is not a proper use case, but it is easy to trigger
> (UFS driver adds opps manually, DTS also adds one). Maybe you prefer to
> handle it differently - exit with ERRNO? Because NULL pointer exception
> in case of proper, but unexpected DTB is not a good way to handle it.
Yeah, sure. I agree that we can return a proper error in that case.
Will look forward to that patch :)
--
viresh
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-04-01 12:03 [PATCH] PM: opp: Fix NULL pointer exception on a v2 table combined with v1 opps Krzysztof Kozlowski
2022-04-04 6:26 ` Viresh Kumar
2022-04-04 6:28 ` Krzysztof Kozlowski
2022-04-04 6:31 ` Viresh Kumar
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