Re: [PATCH] PCI: cadence: Fix NULL pointer error for ops
From: Chen Wang
Date: Fri Mar 07 2025 - 09:44:30 EST
On 2025/3/7 21:47, Siddharth Vadapalli wrote:
On Fri, Mar 07, 2025 at 09:07:35PM +0800, Chen Wang wrote:
Hello~
Any comment on this? Or can we have this bugfix patch picked for coming
v6.15?
Is there a driver in Linux which is affected by the issue that you are
trying to fix in this patch? Please point to the driver since I don't
see such a driver.
Regards,
Siddharth.
Oh, sorry I didn't explain the change history clearly. I am developing a
PCIe driver for a new soc (SG2042), and this PCIe controller uses
cadence's IP. In the code, I found that if I don't assign a value to
cdns_pcie.ops, it will crash during operation. At first, I didn't fix
the bug in the cadence code, but used a workaround in the SG2042 driver.
Later in the code review, Manivannan pointed out my problem and hoped
that I would submit a patch to fix this problem in the cadence driver.
Adding Manivannan who should know about this.
Please take a look at this:
https://lore.kernel.org/linux-riscv/20250119122353.v3tzitthmu5tu3dg@thinkpad/.
For your convenience, I have excerpted some of the text below.
```
> +static struct pci_ops sg2042_pcie_host_ops = {
> + .map_bus = cdns_pci_map_bus,
> + .read = sg2042_pcie_config_read,
> + .write = sg2042_pcie_config_write,
> +};
> +
> +/* Dummy ops which will be assigned to cdns_pcie.ops, which must be
!NULL. */
Because cadence code driver doesn't check for !ops? Please fix it
instead. And
the fix is trivial.
> +static const struct cdns_pcie_ops sg2042_cdns_pcie_ops = {};
> +
> +static int sg2042_pcie_probe(struct platform_device *pdev)
> +{
[......]
> + struct cdns_pcie *cdns_pcie;
[......]
> + cdns_pcie->ops = &sg2042_cdns_pcie_ops;
> + pcie->cdns_pcie = cdns_pcie;
```
Regards,
Chen
Regards,
Chen
On 2025/3/4 16:17, Chen Wang wrote:
From: Chen Wang <unicorn_wang@xxxxxxxxxxx>
ops of struct cdns_pcie may be NULL, direct use
will result in a null pointer error.
Add checking of pcie->ops before using it.
Fixes: 40d957e6f9eb ("PCI: cadence: Add support to start link and verify link status")
Signed-off-by: Chen Wang <unicorn_wang@xxxxxxxxxxx>
---
drivers/pci/controller/cadence/pcie-cadence-host.c | 2 +-
drivers/pci/controller/cadence/pcie-cadence.c | 4 ++--
drivers/pci/controller/cadence/pcie-cadence.h | 6 +++---
3 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
index 8af95e9da7ce..9b9d7e722ead 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-host.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
@@ -452,7 +452,7 @@ static int cdns_pcie_host_init_address_translation(struct cdns_pcie_rc *rc)
cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_PCI_ADDR1(0), addr1);
cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_DESC1(0), desc1);
- if (pcie->ops->cpu_addr_fixup)
+ if (pcie->ops && pcie->ops->cpu_addr_fixup)
cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(12) |
diff --git a/drivers/pci/controller/cadence/pcie-cadence.c b/drivers/pci/controller/cadence/pcie-cadence.c
index 204e045aed8c..56c3d6cdd70e 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.c
+++ b/drivers/pci/controller/cadence/pcie-cadence.c
@@ -90,7 +90,7 @@ void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 busnr, u8 fn,
cdns_pcie_writel(pcie, CDNS_PCIE_AT_OB_REGION_DESC1(r), desc1);
/* Set the CPU address */
- if (pcie->ops->cpu_addr_fixup)
+ if (pcie->ops && pcie->ops->cpu_addr_fixup)
cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(nbits) |
@@ -120,7 +120,7 @@ void cdns_pcie_set_outbound_region_for_normal_msg(struct cdns_pcie *pcie,
}
/* Set the CPU address */
- if (pcie->ops->cpu_addr_fixup)
+ if (pcie->ops && pcie->ops->cpu_addr_fixup)
cpu_addr = pcie->ops->cpu_addr_fixup(pcie, cpu_addr);
addr0 = CDNS_PCIE_AT_OB_REGION_CPU_ADDR0_NBITS(17) |
diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
index f5eeff834ec1..436630d18fe0 100644
--- a/drivers/pci/controller/cadence/pcie-cadence.h
+++ b/drivers/pci/controller/cadence/pcie-cadence.h
@@ -499,7 +499,7 @@ static inline u32 cdns_pcie_ep_fn_readl(struct cdns_pcie *pcie, u8 fn, u32 reg)
static inline int cdns_pcie_start_link(struct cdns_pcie *pcie)
{
- if (pcie->ops->start_link)
+ if (pcie->ops && pcie->ops->start_link)
return pcie->ops->start_link(pcie);
return 0;
@@ -507,13 +507,13 @@ static inline int cdns_pcie_start_link(struct cdns_pcie *pcie)
static inline void cdns_pcie_stop_link(struct cdns_pcie *pcie)
{
- if (pcie->ops->stop_link)
+ if (pcie->ops && pcie->ops->stop_link)
pcie->ops->stop_link(pcie);
}
static inline bool cdns_pcie_link_up(struct cdns_pcie *pcie)
{
- if (pcie->ops->link_up)
+ if (pcie->ops && pcie->ops->link_up)
return pcie->ops->link_up(pcie);
return true;
base-commit: 7eb172143d5508b4da468ed59ee857c6e5e01da6