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Date: Mon, 13 Jun 2016 11:04:07 +0100
From: Bruce Richardson <bruce.richardson@intel.com>
To: Slawomir Mrozowicz <slawomirx.mrozowicz@intel.com>
Cc: helin.zhang@intel.com, jingjing.wu@intel.com, dev@dpdk.org
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Subject: Re: [dpdk-dev] [PATCH] i40e: Unchecked return value
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On Mon, May 23, 2016 at 02:25:15PM +0200, Slawomir Mrozowicz wrote:
> Calling i40e_switch_tx_queue without checking return value.
> Fixed by add warning log information if return failed.
>
> Fixes: 71d35259ff67 ("i40e: tear down flow director")
> Coverity ID 13208
>
> Signed-off-by: Slawomir Mrozowicz <slawomirx.mrozowicz@intel.com>
> ---
> drivers/net/i40e/i40e_fdir.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/i40e/i40e_fdir.c b/drivers/net/i40e/i40e_fdir.c
> index 8aa41e5..d0bdf2c 100644
> --- a/drivers/net/i40e/i40e_fdir.c
> +++ b/drivers/net/i40e/i40e_fdir.c
> @@ -288,11 +288,14 @@ i40e_fdir_teardown(struct i40e_pf *pf)
> {
> struct i40e_hw *hw = I40E_PF_TO_HW(pf);
> struct i40e_vsi *vsi;
> + int err = I40E_SUCCESS;
>
> vsi = pf->fdir.fdir_vsi;
> if (!vsi)
> return;
> - i40e_switch_tx_queue(hw, vsi->base_queue, FALSE);
> + err = i40e_switch_tx_queue(hw, vsi->base_queue, FALSE);
> + if (err)
> + PMD_DRV_LOG(WARNING, "Failed to do FDIR TX switch off.");
> i40e_switch_rx_queue(hw, vsi->base_queue, FALSE);
So, we have a failure when we can't swtich off flow director in a queue. How
serious is this? Is it something that can be completely ignored, or is printing
a warning sufficient? What, if anything, should the user do about the warning?
I'm just concerned that this patch doesn't seem to help the overall usability
of DPDK much. We print a warning, which will probably be of absolutely no use
to the user at all. It doesn't tell the user what the failure will mean in
practical terms - will the failure mean that transmit won't work, that packets
may be corrupted, may go out on a wrong queue, etc., or how the user can prevent
the error from happening in the future.
Please review patch to ensure this is the best way to fix this error - if any
fix is needed. If the error doesn't cause any problematic user effects, then
just mark the coverity issue as a false positive (or does it work casting the
function to (void) as it is called?). If the error does have problematic effects,
please provide useful information to the user.
/Bruce