On Tue, Jan 31, 2017 at 04:33:15PM +0100, Geert Uytterhoeven wrote: > Hi Bjorn, > > On Tue, Jan 31, 2017 at 4:10 PM, Bjorn Helgaas <[email protected]> wrote: > > A match in the rcar_pcie_of_match[] table is required, so check that first, > > before we start setting up things that need to be undone if it fails. No > > functional change intended. > > > > Signed-off-by: Bjorn Helgaas <[email protected]> > > --- > > drivers/pci/host/pcie-rcar.c | 10 +++++----- > > 1 file changed, 5 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c > > index 0d9b96c3c49d..c91ff0b91be8 100644 > > --- a/drivers/pci/host/pcie-rcar.c > > +++ b/drivers/pci/host/pcie-rcar.c > > @@ -1129,6 +1129,10 @@ static int rcar_pcie_probe(struct platform_device > > *pdev) > > int err; > > int (*hw_init_fn)(struct rcar_pcie *); > > > > + of_id = of_match_device(rcar_pcie_of_match, dev); > > + if (!of_id || !of_id->data) > > + return -EINVAL; > > + > > As this driver is DT-only, none of the above can fail, and you could just do > > hw_init_fn = of_device_get_match_data(dev); > > instead, getting rid of of_id completely.
Oh, I really like that, thanks for pointing that out! I was about to say that I personally would not check of_id->data for NULL, because it is only NULL if somebody adds an entry to rcar_pcie_of_match without a .data member. In that case, I'd rather take the NULL pointer dereference than return -EINVAL because it's too easy to ignore the -EINVAL. What do you think about the following? commit 25bd3aa972ee32f04590aa68b2b785dce36b036a Author: Bjorn Helgaas <[email protected]> Date: Tue Jan 31 08:45:49 2017 -0600 PCI: rcar: Use of_device_get_match_data() to simplify probe This is a DT-only driver, so the only way to call rcar_pcie_probe() is to match an entry in rcar_pcie_of_match[], so of_id cannot be NULL. Furthermore, of_id->data can only be NULL if an rcar_pcie_of_match[] entry has a NULL .data member. That's a driver defect, and we don't want to return -EINVAL, which is easy to ignore. We'd rather take the NULL pointer dereference so we notice the problem and fix it. Use of_device_get_match_data() to retrieve the hw_init_fn pointer. No functional change intended. Suggested-by: Geert Uytterhoeven <[email protected]> Signed-off-by: Bjorn Helgaas <[email protected]> diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c index 0d9b96c3c49d..cb07c45c1858 100644 --- a/drivers/pci/host/pcie-rcar.c +++ b/drivers/pci/host/pcie-rcar.c @@ -1125,7 +1125,6 @@ static int rcar_pcie_probe(struct platform_device *pdev) struct device *dev = &pdev->dev; struct rcar_pcie *pcie; unsigned int data; - const struct of_device_id *of_id; int err; int (*hw_init_fn)(struct rcar_pcie *); @@ -1149,11 +1148,6 @@ static int rcar_pcie_probe(struct platform_device *pdev) if (err) return err; - of_id = of_match_device(rcar_pcie_of_match, dev); - if (!of_id || !of_id->data) - return -EINVAL; - hw_init_fn = of_id->data; - pm_runtime_enable(dev); err = pm_runtime_get_sync(dev); if (err < 0) { @@ -1162,6 +1156,7 @@ static int rcar_pcie_probe(struct platform_device *pdev) } /* Failure to get a link might just be that no cards are inserted */ + hw_init_fn = of_device_get_match_data(dev); err = hw_init_fn(pcie); if (err) { dev_info(dev, "PCIe link down\n");
