linux-kernel - Re: [PATCH v2 1/2] platform/x86: amd-pmc: Store the pci_dev instance inside struct amd_pmc

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Message-ID: <7714d522-36b4-47bd-332c-c4ff5eeb1237@amd.com>
Date:   Fri, 22 Oct 2021 12:25:47 +0530
From:   "Goswami, Sanket" <Sanket.Goswami@....com>
To:     Hans de Goede <hdegoede@...hat.com>, Shyam-sundar.S-k@....com,
        mgross@...ux.intel.com
Cc:     platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] platform/x86: amd-pmc: Store the pci_dev instance
 inside struct amd_pmc_dev

Hi Hans,

On 21-Oct-21 23:48, Hans de Goede wrote:
> [CAUTION: External Email]
> 
> Hi,
> 
> On 10/21/21 11:29, Sanket Goswami wrote:
>> Store the root port information in amd_pmc_probe() so that the
>> information can be used across multiple routines.
>>
>> Signed-off-by: Sanket Goswami <Sanket.Goswami@....com>
>> ---
>> Changes in v2:
>> - Store the rdev info in amd_pmc_probe() as suggested by Hans.
> 
> Thank you, but there are still some issues, see below.
> 
> 
>>  drivers/platform/x86/amd-pmc.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/platform/x86/amd-pmc.c b/drivers/platform/x86/amd-pmc.c
>> index 55f14bdfdbfd..502f37eaba1f 100644
>> --- a/drivers/platform/x86/amd-pmc.c
>> +++ b/drivers/platform/x86/amd-pmc.c
>> @@ -119,6 +119,7 @@ struct amd_pmc_dev {
>>       u16 minor;
>>       u16 rev;
>>       struct device *dev;
>> +     struct pci_dev *rdev;
>>       struct mutex lock; /* generic mutex lock */
>>  #if IS_ENABLED(CONFIG_DEBUG_FS)
>>       struct dentry *dbgfs_dir;
>> @@ -482,6 +483,7 @@ static int amd_pmc_probe(struct platform_device *pdev)
>>               return -ENODEV;
>>       }
>>
>> +     dev->rdev = rdev;
>>       dev->cpu_id = rdev->device;
>>       err = pci_write_config_dword(rdev, AMD_PMC_SMU_INDEX_ADDRESS, AMD_PMC_BASE_ADDR_LO);
>>       if (err) {
>> @@ -512,7 +514,6 @@ static int amd_pmc_probe(struct platform_device *pdev)
>>       }
>>
>>       base_addr_hi = val & AMD_PMC_BASE_ADDR_LO_MASK;
>> -     pci_dev_put(dev->rdev);
> 
> The current code here actually reads:
> 
>         pci_dev_put(rdev);
> 
> Note (rdev) not (dev->rdev). I don't know what you based this on, this is weird.

rdev is already retrieved before doing this:
	     pci_dev_put(dev->rdev);

i.e.
in amd_pmc_probe()

rdev = pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(0, 0));
	if (!rdev || !pci_match_id(pmc_pci_ids, rdev)) {
		pci_dev_put(rdev);
		return -ENODEV;
	}

after this I am storing rdev in "dev->rdev"
i.e.
dev->rdev = rdev;

after this I am using "dev->rdev" at places where "rdev" was getting used earlier.
Do you see any problem?

> 
> Also there are a bunch of error-exits from amd_pmc_probe() which not all
> need a "pci_dev_put(rdev)" added to them before there "return ERROR;"
> statement.
> 
> It would be best to add:
> 
> err_pci_dev_put:
>         pci_dev_put(rdev);
>         return err;
> 
> Add the end off the function (after the return 0;) and replace all
> "return FOO" error-exits with:
> 
>                 err = <FOO>;
>                 goto err_pci_dev_put;
>         }
> 
Thank you, will take it as a separate patch in v3.


Thanks,
Sanket