pcie-rockchip-ep.c coverity issue #1437163

pcie-rockchip-ep.c coverity issue #1437163

[Bjorn Helgaas]

Hi Shawn,

Please take a look at this issue reported by Coverity:

332 static int rockchip_pcie_ep_get_msi(struct pci_epc *epc, u8 fn)
333 {
334        struct rockchip_pcie_ep *ep = epc_get_drvdata(epc);
335        struct rockchip_pcie *rockchip = &ep->rockchip;
336        u16 flags;
337
338        flags = rockchip_pcie_read(rockchip,
339                                   ROCKCHIP_PCIE_EP_FUNC_BASE(fn) +
340                                   ROCKCHIP_PCIE_EP_MSI_CTRL_REG);

CID 1437163 (#2 of 2): Operands don't affect result
(CONSTANT_EXPRESSION_RESULT) result_independent_of_operands: flags &
(65536UL /* 1UL << 16 */) is always 0 regardless of the values of its
operands. This occurs as the logical operand of !.

341        if (!(flags & ROCKCHIP_PCIE_EP_MSI_CTRL_ME))
342                return -EINVAL;

Re: pcie-rockchip-ep.c coverity issue #1437163

[Bjorn Helgaas]

On Tue, Oct 27, 2020 at 11:16:38AM -0500, Bjorn Helgaas wrote:
> Hi Shawn,
> 
> Please take a look at this issue reported by Coverity:
> 
> 332 static int rockchip_pcie_ep_get_msi(struct pci_epc *epc, u8 fn)
> 333 {
> 334        struct rockchip_pcie_ep *ep = epc_get_drvdata(epc);
> 335        struct rockchip_pcie *rockchip = &ep->rockchip;
> 336        u16 flags;
> 337
> 338        flags = rockchip_pcie_read(rockchip,
> 339                                   ROCKCHIP_PCIE_EP_FUNC_BASE(fn) +
> 340                                   ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
> 
> CID 1437163 (#2 of 2): Operands don't affect result
> (CONSTANT_EXPRESSION_RESULT) result_independent_of_operands: flags &
> (65536UL /* 1UL << 16 */) is always 0 regardless of the values of its
> operands. This occurs as the logical operand of !.
> 
> 341        if (!(flags & ROCKCHIP_PCIE_EP_MSI_CTRL_ME))
> 342                return -EINVAL;

The same issue also occurs in rockchip_pcie_ep_send_msi_irq()
(Coverity issue #143765 for that one).

Re: pcie-rockchip-ep.c coverity issue #1437163

[Bjorn Helgaas]

[+cc Krzysztof]

On Wed, Oct 28, 2020 at 08:34:45AM +0800, Shawn Lin wrote:
> On 2020/10/28 0:16, Bjorn Helgaas wrote:
> > Hi Shawn,
> > 
> > Please take a look at this issue reported by Coverity:
> > 
> > 332 static int rockchip_pcie_ep_get_msi(struct pci_epc *epc, u8 fn)
> > 333 {
> > 334        struct rockchip_pcie_ep *ep = epc_get_drvdata(epc);
> > 335        struct rockchip_pcie *rockchip = &ep->rockchip;
> > 336        u16 flags;
> > 337
> > 338        flags = rockchip_pcie_read(rockchip,
> > 339                                   ROCKCHIP_PCIE_EP_FUNC_BASE(fn) +
> > 340                                   ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
> > 
> > CID 1437163 (#2 of 2): Operands don't affect result
> > (CONSTANT_EXPRESSION_RESULT) result_independent_of_operands: flags &
> > (65536UL /* 1UL << 16 */) is always 0 regardless of the values of its
> > operands. This occurs as the logical operand of !.
> > 
> > 341        if (!(flags & ROCKCHIP_PCIE_EP_MSI_CTRL_ME))
> > 342                return -EINVAL;
> 
> Actually it should be BIT(0) instead of BIT(16),
> I will fix it, thanks.

Just a quick reminder about this and the similar issue in
rockchip_pcie_ep_send_msi_irq().

Your response above didn't seem to make it to the archive, so maybe
your patch to fix it also got lost?

Krzysztof also pointed out that rockchip_pcie_read() returns u32,
while flags is only u16.

Bjorn

Re: pcie-rockchip-ep.c coverity issue #1437163

[Shawn Lin]

在 2020/12/24 5:04, Bjorn Helgaas 写道:
> [+cc Krzysztof]
> 
> On Wed, Oct 28, 2020 at 08:34:45AM +0800, Shawn Lin wrote:
>> On 2020/10/28 0:16, Bjorn Helgaas wrote:
>>> Hi Shawn,
>>>
>>> Please take a look at this issue reported by Coverity:
>>>
>>> 332 static int rockchip_pcie_ep_get_msi(struct pci_epc *epc, u8 fn)
>>> 333 {
>>> 334        struct rockchip_pcie_ep *ep = epc_get_drvdata(epc);
>>> 335        struct rockchip_pcie *rockchip = &ep->rockchip;
>>> 336        u16 flags;
>>> 337
>>> 338        flags = rockchip_pcie_read(rockchip,
>>> 339                                   ROCKCHIP_PCIE_EP_FUNC_BASE(fn) +
>>> 340                                   ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
>>>
>>> CID 1437163 (#2 of 2): Operands don't affect result
>>> (CONSTANT_EXPRESSION_RESULT) result_independent_of_operands: flags &
>>> (65536UL /* 1UL << 16 */) is always 0 regardless of the values of its
>>> operands. This occurs as the logical operand of !.
>>>
>>> 341        if (!(flags & ROCKCHIP_PCIE_EP_MSI_CTRL_ME))
>>> 342                return -EINVAL;
>>
>> Actually it should be BIT(0) instead of BIT(16),
>> I will fix it, thanks.
> 
> Just a quick reminder about this and the similar issue in
> rockchip_pcie_ep_send_msi_irq().
> 
> Your response above didn't seem to make it to the archive, so maybe
> your patch to fix it also got lost?
> 
> Krzysztof also pointed out that rockchip_pcie_read() returns u32,
> while flags is only u16.
> 

Thanks for reminder. I didn't notice my previous patch hadn't arrived at
the archive but I just sent again a few minutes ago.

> Bjorn
> 
> 
>