On Tue, Jun 14, 2022 at 05:23:33PM +0900, Damien Le Moal wrote: > On 6/10/22 17:17, Serge Semin wrote: > > Having greater than AHCI_MAX_PORTS (32) ports detected isn't that critical > > from the further AHCI-platform initialization point of view since > > exceeding the ports upper limit will cause allocating more resources than > > will be used afterwards. But detecting too many child DT-nodes doesn't > > seem right since it's very unlikely to have it on an ordinary platform. In > > accordance with the AHCI specification there can't be more than 32 ports > > implemented at least due to having the CAP.NP field of 5 bits wide and the > > PI register of dword size. Thus if such situation is found the DTB must > > have been corrupted and the data read from it shouldn't be reliable. Let's > > consider that as an erroneous situation and halt further resources > > allocation. > > > > Note it's logically more correct to have the nports set only after the > > initialization value is checked for being sane. So while at it let's make > > sure nports is assigned with a correct value. > > > > Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx> > > Reviewed-by: Hannes Reinecke <hare@xxxxxxx> > > > > --- > > > > Changelog v2: > > - Drop the else word from the child_nodes value checking if-else-if > > statement (@Damien) and convert the after-else part into the ternary > > operator-based statement. > > > > Changelog v4: > > - Fix some logical mistakes in the patch log. (@Sergei Shtylyov) > > --- > > drivers/ata/libahci_platform.c | 13 ++++++++++--- > > 1 file changed, 10 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/ata/libahci_platform.c b/drivers/ata/libahci_platform.c > > index 814804582d1d..8aed7b29c7ab 100644 > > --- a/drivers/ata/libahci_platform.c > > +++ b/drivers/ata/libahci_platform.c > > @@ -451,15 +451,22 @@ struct ahci_host_priv *ahci_platform_get_resources(struct platform_device *pdev, > > } > > } > > > > - hpriv->nports = child_nodes = of_get_child_count(dev->of_node); > > + /* > > + * Too many sub-nodes most likely means having something wrong with > > + * the firmware. > > + */ > > + child_nodes = of_get_child_count(dev->of_node); > > + if (child_nodes > AHCI_MAX_PORTS) { > > + rc = -EINVAL; > > + goto err_out; > > + } > > > > /* > > * If no sub-node was found, we still need to set nports to > > * one in order to be able to use the > > * ahci_platform_[en|dis]able_[phys|regulators] functions. > > */ > > - if (!child_nodes) > > - hpriv->nports = 1; > > + hpriv->nports = child_nodes ?: 1; > > This change is not necessary and makes the code far less easy to read. elaborate please. What change? What part of this change makes the code less easy to read? -Sergey > > > > > hpriv->phys = devm_kcalloc(dev, hpriv->nports, sizeof(*hpriv->phys), GFP_KERNEL); > > if (!hpriv->phys) { > > > -- > Damien Le Moal > Western Digital Research