Re: [PATCH] net: ath9k: use devm for request_irq

["Toke Høiland-Jørgensen" <toke@kernel.org>]

Felix Fietkau <nbd@nbd.name> writes:

> On 07.08.24 22:07, Rosen Penev wrote:
>> On Wed, Aug 7, 2024 at 1:05 PM Felix Fietkau <nbd@nbd.name> wrote:
>>>
>>> On 07.08.24 20:52, Rosen Penev wrote:
>>> > On Wed, Aug 7, 2024 at 10:47 AM Felix Fietkau <nbd@nbd.name> wrote:
>>> >>
>>> >> On 31.07.24 23:02, Rosen Penev wrote:
>>> >> > Avoids having to manually call free_irq. Simplifies code slightly.
>>> >> >
>>> >> > Signed-off-by: Rosen Penev <rosenp@gmail.com>
>>> >> > ---
>>> >> >   drivers/net/wireless/ath/ath9k/ahb.c | 7 ++-----
>>> >> >   drivers/net/wireless/ath/ath9k/pci.c | 9 +++------
>>> >> >   2 files changed, 5 insertions(+), 11 deletions(-)
>>> >> >
>>> >> > diff --git a/drivers/net/wireless/ath/ath9k/ahb.c b/drivers/net/wireless/ath/ath9k/ahb.c
>>> >> > index 1a6697b6e3b4..29f67ded8fe2 100644
>>> >> > --- a/drivers/net/wireless/ath/ath9k/ahb.c
>>> >> > +++ b/drivers/net/wireless/ath/ath9k/ahb.c
>>> >> > @@ -118,7 +118,7 @@ static int ath_ahb_probe(struct platform_device *pdev)
>>> >> >       sc->mem = mem;
>>> >> >       sc->irq = irq;
>>> >> >
>>> >> > -     ret = request_irq(irq, ath_isr, IRQF_SHARED, "ath9k", sc);
>>> >> > +     ret = devm_request_irq(&pdev->dev, irq, ath_isr, IRQF_SHARED, "ath9k", sc);
>>> >> Sorry for the late response, but I think this patch is wrong any may
>>> >> need to be reverted. If there is an error during probe, and the IRQ
>>> >> fires for some reason, there could be an use-after-free bug when the IRQ
>>> >> handler accesses the data in sc.
>>> >> The explicit freq_irq calls were preventing that from happening.
>>> > How about keeping the devm variant and replacing free_irq with
>>> > devm_free_irq in probe?
>>>
>>> If you do that, then using the devm variant is completely pointless.
>>> I think a full revert is the best option.
>> OTOH it still allows removing free_irq from _remove, but I see your point.
>
> No, because you'd have the same use-after-free bug there as well.

Alright, let's revert. Kalle, can you just do the revert, or should I
send a patch for it?

-Toke