Re: [PATCH] wifi: brcmfmac: unmap dma buffer in brcmf_msgbuf_alloc_pktid()

[Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx>]

On 12/22/2022 9:52 AM, shaozhengchao wrote:
> On 2022/12/22 16:46, Kalle Valo wrote:
> > Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> writes:
> >
> > > On 2022-12-21 18:33:06 [+0000], Kalle Valo wrote:
> > > > Zhengchao Shao <shaozhengchao@xxxxxxxxxx> wrote:
> > > >
> > > > > After the DMA buffer is mapped to a physical address, address is 
> > > > > stored
> > > > > in pktids in brcmf_msgbuf_alloc_pktid(). Then, pktids is parsed in
> > > > > brcmf_msgbuf_get_pktid()/brcmf_msgbuf_release_array() to obtain 
> > > > > physaddr
> > > > > and later unmap the DMA buffer. But when count is always equal to
> > > > > pktids->array_size, physaddr isn't stored in pktids and the DMA buffer
> > > > > will not be unmapped anyway.
> > > > >
> > > > > Fixes: 9a1bb60250d2 ("brcmfmac: Adding msgbuf protocol.")
> > > > > Signed-off-by: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
> > > >
> > > > Can someone review this?
> > >
> > > After looking at the code, that skb is mapped but not inserted into the
> > > ringbuffer in this condition. The function returns with an error and the
> > > caller will free that skb (or add to a list for later). Either way the
> > > skb remains mapped which is wrong. The unmap here is the right thing to
> > > do.
> > >
> > > Reviewed-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> >
> > Thanks for the review, very much appreciated.
>
> Thank you very much.

Good catch. Has this path been observed or is this found by inspecting 
the code? Just curious.

Regards,
Arend

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