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Message-ID: <f908005c-7c27-ad94-721d-100a635932c2@linux.intel.com>
Date: Fri, 25 Jan 2019 09:03:18 -0600
From: Thor Thayer <thor.thayer@...ux.intel.com>
To: Atsushi Nemoto <atsushi.nemoto@...d.co.jp>, netdev@...r.kernel.org
Cc: Dalon L Westergreen <dalon.westergreen@...ux.intel.com>,
Tomonori Sakita <tomonori.sakita@...d.co.jp>
Subject: Re: [PATCH v2] net: altera_tse: fix msgdma_tx_completion on non-zero
fill_level case
On 1/24/19 8:02 PM, Atsushi Nemoto wrote:
> From: Tomonori Sakita <tomonori.sakita@...d.co.jp>
>
> If fill_level was not zero and status was not BUSY,
> result of "tx_prod - tx_cons - inuse" might be zero.
> Subtracting 1 unconditionally results invalid negative return value
> on this case.
> Make sure not to return an negative value.
>
> Signed-off-by: Tomonori Sakita <tomonori.sakita@...d.co.jp>
> Signed-off-by: Atsushi Nemoto <atsushi.nemoto@...d.co.jp>
> Reviewed-by: Dalon L Westergreen <dalon.westergreen@...ux.intel.com>
> ---
> Changes in v2:
> Use max_t instead of just removing the "- 1".
>
> drivers/net/ethernet/altera/altera_msgdma.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/altera/altera_msgdma.c b/drivers/net/ethernet/altera/altera_msgdma.c
> index 0fb986b..0ae723f 100644
> --- a/drivers/net/ethernet/altera/altera_msgdma.c
> +++ b/drivers/net/ethernet/altera/altera_msgdma.c
> @@ -145,7 +145,8 @@ u32 msgdma_tx_completions(struct altera_tse_private *priv)
> & 0xffff;
>
> if (inuse) { /* Tx FIFO is not empty */
> - ready = priv->tx_prod - priv->tx_cons - inuse - 1;
> + ready = max_t(int,
> + priv->tx_prod - priv->tx_cons - inuse - 1, 0);
> } else {
> /* Check for buffered last packet */
> status = csrrd32(priv->tx_dma_csr, msgdma_csroffs(status));
>
Thanks for the patch!
Acked-by: Thor Thayer <thor.thayer@...ux.intel.com>
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