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

Niklas Cassel
2024-10-21T11:45:24Z

On Mon, Oct 21, 2024 at 12:26:15PM +0100, Ryan Roberts wrote:
> 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
> */

Sounds good to me!

Kind regards,
Niklas