On Tue, Dec 22, 2020 at 12:26 AM Andrew Lunn <and...@lunn.ch> wrote:
>
> On Mon, Dec 21, 2020 at 02:43:23PM +0900, Masahiro Yamada wrote:
> > The declaration of request_irq() in <linux/interrupt.h> is marked as
> > __must_check.
> >
> > Without the return value check, I see the following warnings:
> >
> > drivers/net/ethernet/lantiq_etop.c: In function 'ltq_etop_hw_init':
> > drivers/net/ethernet/lantiq_etop.c:273:4: warning: ignoring return value of
> > 'request_irq', declared with attribute warn_unused_result [-Wunused-result]
> > 273 | request_irq(irq, ltq_etop_dma_irq, 0, "etop_tx", priv);
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > drivers/net/ethernet/lantiq_etop.c:281:4: warning: ignoring return value of
> > 'request_irq', declared with attribute warn_unused_result [-Wunused-result]
> > 281 | request_irq(irq, ltq_etop_dma_irq, 0, "etop_rx", priv);
> > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
> > Reported-by: Miguel Ojeda <oj...@kernel.org>
> > Signed-off-by: Masahiro Yamada <masahi...@kernel.org>
> > ---
> >
> > drivers/net/ethernet/lantiq_etop.c | 13 +++++++++++--
> > 1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/lantiq_etop.c
> > b/drivers/net/ethernet/lantiq_etop.c
> > index 2d0c52f7106b..960494f9752b 100644
> > --- a/drivers/net/ethernet/lantiq_etop.c
> > +++ b/drivers/net/ethernet/lantiq_etop.c
> > @@ -264,13 +264,18 @@ ltq_etop_hw_init(struct net_device *dev)
> > for (i = 0; i < MAX_DMA_CHAN; i++) {
> > int irq = LTQ_DMA_CH0_INT + i;
> > struct ltq_etop_chan *ch = &priv->ch[i];
> > + int ret;
> >
> > ch->idx = ch->dma.nr = i;
> > ch->dma.dev = &priv->pdev->dev;
> >
> > if (IS_TX(i)) {
> > ltq_dma_alloc_tx(&ch->dma);
> > - request_irq(irq, ltq_etop_dma_irq, 0, "etop_tx",
> > priv);
> > + ret = request_irq(irq, ltq_etop_dma_irq, 0,
> > "etop_tx", priv);
> > + if (ret) {
> > + netdev_err(dev, "failed to request irq\n");
> > + return ret;
>
> You need to cleanup what ltq_dma_alloc_tx() did.
Any failure from this function will roll back
in the following paths:
ltq_etop_hw_exit()
-> ltq_etop_free_channel()
-> ltq_dma_free()
So, dma is freed anyway.
One problem I see is,
ltq_etop_hw_exit() frees all DMA channels,
some of which may not have been allocated yet.
If it is a bug, it is an existing bug.
>
> > + }
> > } else if (IS_RX(i)) {
> > ltq_dma_alloc_rx(&ch->dma);
> > for (ch->dma.desc = 0; ch->dma.desc < LTQ_DESC_NUM;
> > @@ -278,7 +283,11 @@ ltq_etop_hw_init(struct net_device *dev)
> > if (ltq_etop_alloc_skb(ch))
> > return -ENOMEM;
This -ENOMEM does not roll back anything here.
As stated above, dma_free_coherent() is called.
The problem is, ltq_etop_hw_exit() rolls back too much.
If your requirement is "this driver is completely wrong. Please rewrite it",
sorry, I cannot (unless I am paid to do so).
I am just following this driver's roll-back model.
Please do not expect more to a person who
volunteers to eliminate build warnings.
Of course, if somebody volunteers to rewrite this driver correctly,
that is appreciated.
> > ch->dma.desc = 0;
> > - request_irq(irq, ltq_etop_dma_irq, 0, "etop_rx",
> > priv);
> > + ret = request_irq(irq, ltq_etop_dma_irq, 0,
> > "etop_rx", priv);
> > + if (ret) {
> > + netdev_err(dev, "failed to request irq\n");
> > + return ret;
>
> And here you need to cleanup ltq_dma_alloc_rx().
>
> Andrew
--
Best Regards
Masahiro Yamada
