Re: [RFC PATCH v1 34/57] sata_sil24: Remove PAGE_SIZE compile-time constant assumption

Ryan Roberts
2024-10-21T11:29:27Z

On 21/10/2024 12:04, Niklas Cassel wrote:
> On Mon, Oct 21, 2024 at 10:24:37AM +0100, Ryan Roberts wrote:
>> On 17/10/2024 13:51, Niklas Cassel wrote:
>>> On Thu, Oct 17, 2024 at 01:42:22PM +0100, Ryan Roberts wrote:
>
> (snip)
>
>> That said, while investigating this, I've spotted a bug in my change. paddr calculation in sil24_qc_issue() is incorrect since sizeof(*pp->cmd_block) is no longer PAGE_SIZE. Based on feedback in another patch, I'm also converting the BUG_ONs to WARN_ON_ONCEs.
>
> Side note: Please wrap you lines to 80 characters max.

Yes sorry, I turned off line wrapping for that last mail because I didn't want
it to wrap the copy/pasted patch. I'll figure out how to mix and match for future.

>
>
>>
>> Additional proposed change, which I'll plan to include in the next version:
>>
>> ---8<---
>> diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
>> index 85c6382976626..c402bf998c4ee 100644
>> --- a/drivers/ata/sata_sil24.c
>> +++ b/drivers/ata/sata_sil24.c
>> @@ -257,6 +257,10 @@ union sil24_cmd_block {
>> struct sil24_atapi_block atapi;
>> };
>>
>> +#define SIL24_ATA_BLOCK_SIZE struct_size_t(struct sil24_ata_block, sge, SIL24_MAX_SGE)
>> +#define SIL24_ATAPI_BLOCK_SIZE struct_size_t(struct sil24_atapi_block, sge, SIL24_MAX_SGE)
>> +#define SIL24_CMD_BLOCK_SIZE max(SIL24_ATA_BLOCK_SIZE, SIL24_ATAPI_BLOCK_SIZE)
>> +
>> static const struct sil24_cerr_info {
>> unsigned int err_mask, action;
>> const char *desc;
>> @@ -886,7 +890,7 @@ static unsigned int sil24_qc_issue(struct ata_queued_cmd *qc)
>> dma_addr_t paddr;
>> void __iomem *activate;
>>
>> - paddr = pp->cmd_block_dma + tag * sizeof(*pp->cmd_block);
>> + paddr = pp->cmd_block_dma + tag * SIL24_CMD_BLOCK_SIZE;
>> activate = port + PORT_CMD_ACTIVATE + tag * 8;
>>
>> /*
>> @@ -1192,7 +1196,7 @@ static int sil24_port_start(struct ata_port *ap)
>> struct device *dev = ap->host->dev;
>> struct sil24_port_priv *pp;
>> union sil24_cmd_block *cb;
>> - size_t cb_size = PAGE_SIZE * SIL24_MAX_CMDS;
>> + size_t cb_size = SIL24_CMD_BLOCK_SIZE * SIL24_MAX_CMDS;
>> dma_addr_t cb_dma;
>>
>> pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL);
>> @@ -1265,8 +1269,8 @@ static int sil24_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>> u32 tmp;
>>
>> /* union sil24_cmd_block must be PAGE_SIZE */
>
> This comment should probably be rephrased to be more clear then, since like
> you said sizeof(union sil24_cmd_block) will no longer be PAGE_SIZE.

How about:

/*
* union sil24_cmd_block must be PAGE_SIZE once taking into account the 'sge'
* flexible array members in struct sil24_atapi_block and struct sil24_ata_block
*/

>
>
>> - BUG_ON(struct_size_t(struct sil24_atapi_block, sge, SIL24_MAX_SGE) != PAGE_SIZE);
>> - BUG_ON(struct_size_t(struct sil24_ata_block, sge, SIL24_MAX_SGE) > PAGE_SIZE);
>> + WARN_ON_ONCE(SIL24_ATAPI_BLOCK_SIZE != PAGE_SIZE);
>> + WARN_ON_ONCE(SIL24_ATA_BLOCK_SIZE != PAGE_SIZE - 16);
>>
>> ata_print_version_once(&pdev->dev, DRV_VERSION);
>> ---8<---