Re: [PATCH] serial: qcom-geni: Drop unsafe rx_buf realloc from setup_fifos()

[Praveen Talari]

Hi

On 24-08-2026 18:26, Greg Kroah-Hartman wrote:
> On Mon, Aug 24, 2026 at 04:15:14PM +0530, Praveen Talari wrote:
> > The RX buffer is allocated once during probe using a fixed DMA_RX_BUF_SIZE
> > and is DMA-mapped for the lifetime of the port. However, setup_fifos()
> > attempts to reallocate rx_buf whenever the reported RX FIFO depth changes.
> > Since the DMA mapping is not re-established after reallocation, the buffer
> > pointer may change while the DMA engine continues using the stale DMA
> > address. This can result in RX DMA targeting memory that no longer
> > corresponds to the active buffer, leading to invalid DMA accesses and
> > potential memory corruption.
> >
> > The RX FIFO depth is unrelated to the size of rx_buf. The buffer is
> > allocated independently using DMA_RX_BUF_SIZE and all RX DMA paths consume
> > it at that fixed size. As such, resizing the buffer based on FIFO depth
> > changes provides no functional benefit.
> >
> > Signed-off-by: Praveen Talari <ptalari@xxxxxxxxxxxx>
> > ---
> > Signed-off-by: Praveen Talari <praveen.talari@xxxxxxxxxxxxxxxx>
> Why is this signed-off-by twice, with different email addresses?

Apologies, that was a mistake while updating the commit message. Only 
praveen.talari@xxxxxxxxxxxxxxxx should be present for upstream 
submissions. I'll fix it in the next revision

Thanks,

Praveen Talari

> confused,
>
> greg k-h