From: "Dr. David Alan Gilbert" <dave@treblig.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: intel-gfx@lists.freedesktop.org, airlied@gmail.com,
mgreer@animalcreek.com, linux-kernel@vger.kernel.org
Subject: Re: [Intel-gfx] ERR_PTR(0) in a couple of places
Date: Sun, 24 Sep 2023 12:16:08 +0000 [thread overview]
Message-ID: <ZRAoiGafRSv7SM6C@gallifrey> (raw)
In-Reply-To: <b3813a4e-3956-254c-a7cf-0fca65dc2cdd@linaro.org>
* Krzysztof Kozlowski (krzysztof.kozlowski@linaro.org) wrote:
> On 24/09/2023 02:41, Dr. David Alan Gilbert wrote:
> > Hi,
> > I randomly noticed there are a couple of places in the kernel that
> > do
> > ERR_PTR(0);
> >
> > and thought that was odd - shouldn't those just be NULL's ?
> >
> > 1) i915
> > drivers/gpu/drm/i915/gt/uc/selftest_guc_multi_lrc.c : 47
> >
> > if (i <= 1)
> > return ERR_PTR(0);
> >
> > from f9d72092cb490
> >
> > 2) trf7970a
> > drivers/nfc/trf7970a.c : 896
> >
> > trf->ignore_timeout =
> > !cancel_delayed_work(&trf->timeout_work);
> > trf->rx_skb = ERR_PTR(0);
>
> I would guess that code is relying on rx_skb being valid pointer or ERR
> (if (!IS_ERR(...))).
If seems mixed, that function calls trf7970a_send_upstream which has
both:
if (trf->rx_skb && !IS_ERR(trf->rx_skb) && !trf->aborting)
print_hex_dump_debug("trf7970a rx data: ", DUMP_PREFIX_NONE,
16, 1, trf->rx_skb->data, trf->rx_skb->len,
false);
and
if (!IS_ERR(trf->rx_skb)) {
kfree_skb(trf->rx_skb);
trf->rx_skb = ERR_PTR(-ECANCELED);
}
It's not clear to me whether it's expecteing that 2nd if to happen or
not.
I notice err.h gained a IS_ERR_OR_NULL to help that case as well.
Dave
> Best regards,
> Krzysztof
>
--
-----Open up your eyes, open up your mind, open up your code -------
/ Dr. David Alan Gilbert | Running GNU/Linux | Happy \
\ dave @ treblig.org | | In Hex /
\ _________________________|_____ http://www.treblig.org |_______/
WARNING: multiple messages have this Message-ID (diff)
From: "Dr. David Alan Gilbert" <dave@treblig.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: matthew.brost@intel.com, mgreer@animalcreek.com,
linux-kernel@vger.kernel.org, airlied@gmail.com,
intel-gfx@lists.freedesktop.org
Subject: Re: ERR_PTR(0) in a couple of places
Date: Sun, 24 Sep 2023 12:16:08 +0000 [thread overview]
Message-ID: <ZRAoiGafRSv7SM6C@gallifrey> (raw)
In-Reply-To: <b3813a4e-3956-254c-a7cf-0fca65dc2cdd@linaro.org>
* Krzysztof Kozlowski (krzysztof.kozlowski@linaro.org) wrote:
> On 24/09/2023 02:41, Dr. David Alan Gilbert wrote:
> > Hi,
> > I randomly noticed there are a couple of places in the kernel that
> > do
> > ERR_PTR(0);
> >
> > and thought that was odd - shouldn't those just be NULL's ?
> >
> > 1) i915
> > drivers/gpu/drm/i915/gt/uc/selftest_guc_multi_lrc.c : 47
> >
> > if (i <= 1)
> > return ERR_PTR(0);
> >
> > from f9d72092cb490
> >
> > 2) trf7970a
> > drivers/nfc/trf7970a.c : 896
> >
> > trf->ignore_timeout =
> > !cancel_delayed_work(&trf->timeout_work);
> > trf->rx_skb = ERR_PTR(0);
>
> I would guess that code is relying on rx_skb being valid pointer or ERR
> (if (!IS_ERR(...))).
If seems mixed, that function calls trf7970a_send_upstream which has
both:
if (trf->rx_skb && !IS_ERR(trf->rx_skb) && !trf->aborting)
print_hex_dump_debug("trf7970a rx data: ", DUMP_PREFIX_NONE,
16, 1, trf->rx_skb->data, trf->rx_skb->len,
false);
and
if (!IS_ERR(trf->rx_skb)) {
kfree_skb(trf->rx_skb);
trf->rx_skb = ERR_PTR(-ECANCELED);
}
It's not clear to me whether it's expecteing that 2nd if to happen or
not.
I notice err.h gained a IS_ERR_OR_NULL to help that case as well.
Dave
> Best regards,
> Krzysztof
>
--
-----Open up your eyes, open up your mind, open up your code -------
/ Dr. David Alan Gilbert | Running GNU/Linux | Happy \
\ dave @ treblig.org | | In Hex /
\ _________________________|_____ http://www.treblig.org |_______/
next prev parent reply other threads:[~2023-09-25 12:59 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-24 0:41 [Intel-gfx] ERR_PTR(0) in a couple of places Dr. David Alan Gilbert
2023-09-24 0:41 ` Dr. David Alan Gilbert
2023-09-24 11:41 ` Krzysztof Kozlowski
2023-09-24 12:16 ` Dr. David Alan Gilbert [this message]
2023-09-24 12:16 ` Dr. David Alan Gilbert
2023-09-25 4:18 ` [Intel-gfx] " Matthew Brost
2023-09-25 4:18 ` Matthew Brost
2023-09-25 4:25 ` [Intel-gfx] " Randy Dunlap
2023-09-25 4:25 ` Randy Dunlap
2023-09-25 15:09 ` [Intel-gfx] " Jani Nikula
2023-09-25 15:09 ` Jani Nikula
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