On Thu, Apr 06, 2023 at 01:43:44PM +0200, Simon Horman wrote: > On Thu, Apr 06, 2023 at 12:23:49PM +0300, Denis Plotnikov wrote: > > > > On 06.04.2023 10:03, Simon Horman wrote: > > > On Wed, Apr 05, 2023 at 02:37:08PM -0500, Bjorn Helgaas wrote: > > > > On Wed, Apr 05, 2023 at 03:04:39PM +0200, Simon Horman wrote: > > > > > On Mon, Apr 03, 2023 at 01:58:49PM +0300, Denis Plotnikov wrote: > > > > > > On 31.03.2023 20:52, Simon Horman wrote: > > > > > > > On Fri, Mar 31, 2023 at 11:06:05AM +0300, Denis Plotnikov wrote: > > > > > > > > Static code analyzer complains to unchecked return value. > > > > > > > > It seems that pci_reset_function return something meaningful > > > > > > > > only if "reset_methods" is set. > > > > > > > > Even if reset_methods isn't used check the return value to avoid > > > > > > > > possible bugs leading to undefined behavior in the future. > > > > > > > > > > > > > > > > Signed-off-by: Denis Plotnikov <den-plotnikov@xxxxxxxxxxxxxx> > > > > > > > nit: The tree this patch is targeted at should be designated, probably > > > > > > > net-next, so the '[PATCH net-next]' in the subject. > > > > > > > > > > > > > > > --- > > > > > > > > drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c | 4 +++- > > > > > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > > > diff --git a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c > > > > > > > > index 87f76bac2e463..39ecfc1a1dbd0 100644 > > > > > > > > --- a/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c > > > > > > > > +++ b/drivers/net/ethernet/qlogic/qlcnic/qlcnic_ctx.c > > > > > > > > @@ -628,7 +628,9 @@ int qlcnic_fw_create_ctx(struct qlcnic_adapter *dev) > > > > > > > > int i, err, ring; > > > > > > > > if (dev->flags & QLCNIC_NEED_FLR) { > > > > > > > > - pci_reset_function(dev->pdev); > > > > > > > > + err = pci_reset_function(dev->pdev); > > > > > > > > + if (err && err != -ENOTTY) > > > > > > > Are you sure about the -ENOTTY part? > > > > > > > > > > > > > > It seems odd to me that an FLR would be required but reset is not supported. > > > > > > No, I'm not sure. My logic is: if the reset method isn't set than > > > > > > pci_reset_function() returns -ENOTTY so treat that result as ok. > > > > > > pci_reset_function may return something different than -ENOTTY only if > > > > > > pci_reset_fn_methods[m].reset_fn is set. > > > > > I see your reasoning: -ENOTTY means nothing happened, and probably that is ok. > > > > > I think my main question is if that can ever happen. > > > > > If that is unknown, then I think this conservative approach makes sense. > > > > The commit log mentions "reset_methods", which I don't think is really > > > > relevant here because reset_methods is an internal implementation > > > > detail. The point is that pci_reset_function() returns 0 if it was > > > > successful and a negative value if it failed. > > > > > > > > If the driver thinks the device needs to be reset, ignoring any > > > > negative return value seems like a mistake because the device was not > > > > reset. > > > > > > > > If the reset is required for a firmware update to take effect, maybe a > > > > diagnostic would be helpful if it fails, e.g., the other "Adapter > > > > initialization failed. Please reboot" messages. > > > > > > > > "QLCNIC_NEED_FLR" suggests that the driver expects an FLR (as opposed > > > > to other kinds of reset). If the driver knows that all qlcnic devices > > > > support FLR, it could use pcie_flr() directly. > > > > > > > > pci_reset_function() does have the possibility that the reset works on > > > > some devices but not all. Secondary Bus Reset fails if there are > > > > other functions on the same bus, e.g., a multi-function device. And > > > > there's some value in doing the reset the same way in all cases. > > > > > > > > So I would suggest something like: > > > > > > > > if (dev->flags & QLCNIC_NEED_FLR) { > > > > err = pcie_flr(dev->pdev); > > > > if (err) { > > > > dev_err(&pdev->dev, "Adapter reset failed (%d). Please reboot\n", err); > > > > return err; > > > > } > > > > dev->flags &= ~QLCNIC_NEED_FLR; > > > > } > > > > > > > > Or, if there are qlcnic devices that don't support FLR: > > > > > > > > if (dev->flags & QLCNIC_NEED_FLR) { > > > > err = pci_reset_function(dev->pdev); > > > > if (err) { > > > > dev_err(&pdev->dev, "Adapter reset failed (%d). Please reboot\n", err); > > > > return err; > > > > } > > > > dev->flags &= ~QLCNIC_NEED_FLR; > > > > } > > > Thanks Bjorn, > > > > > > that is very helpful. > > > > > > I think that in order to move to option #1 some information would be needed > > > from those familiar with the device(s). As it is a more invasive change - > > > pci_reset_function -> pcie_flr. > > > > > > So my feeling is that, in lieu of such feedback, option #2 is a good > > > improvement on the current code. > > > > > > OTOH, this driver is 'Supported' as opposed to 'Maintained'. > > > So perhaps we can just use our best judgement and go for option #1. > > > > So, it looks like option #2 is the safest choice as we do reset only if FLR > > is needed (when pci_reset_function() makes sense) > > > > If all agree with that I'll re-send the path > > Yes. Maybe wait 24h, and if there is no further feedback go ahead with that > plan? Perhaps a code comment, or the patch description could include some information about the reasoning above.