Hello Ryan, While I realize that this has not always been consistent, please prefix the subject with "ata: ", so that it becomes "ata: sata_sil24: ". On Mon, Oct 14, 2024 at 11:58:41AM +0100, Ryan Roberts wrote: > To prepare for supporting boot-time page size selection, refactor code > to remove assumptions about PAGE_SIZE being compile-time constant. Code > intended to be equivalent when compile-time page size is active. > > Convert "struct sil24_ata_block" and "struct sil24_atapi_block" to use a > flexible array member for their sge[] array. The previous static size of > SIL24_MAX_SGE depends on PAGE_SIZE so doesn't work for boot-time page > size. > > Wrap global variables that are initialized with PAGE_SIZE derived values > using DEFINE_GLOBAL_PAGE_SIZE_VAR() so their initialization can be > deferred for boot-time page size builds. > > Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> > --- > > ***NOTE*** > Any confused maintainers may want to read the cover note here for context: > https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@xxxxxxx/ > > drivers/ata/sata_sil24.c | 46 +++++++++++++++++++--------------------- > 1 file changed, 22 insertions(+), 24 deletions(-) > > diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c > index 72c03cbdaff43..85c6382976626 100644 > --- a/drivers/ata/sata_sil24.c > +++ b/drivers/ata/sata_sil24.c > @@ -42,26 +42,25 @@ struct sil24_sge { > __le32 flags; > }; > > +/* > + * sil24 fetches in chunks of 64bytes. The first block > + * contains the PRB and two SGEs. From the second block, it's > + * consisted of four SGEs and called SGT. Calculate the > + * number of SGTs that fit into one page. > + */ > +#define SIL24_PRB_SZ (sizeof(struct sil24_prb) + 2 * sizeof(struct sil24_sge)) > +#define SIL24_MAX_SGT ((PAGE_SIZE - SIL24_PRB_SZ) / (4 * sizeof(struct sil24_sge))) > + > +/* > + * This will give us one unused SGEs for ATA. This extra SGE > + * will be used to store CDB for ATAPI devices. > + */ > +#define SIL24_MAX_SGE (4 * SIL24_MAX_SGT + 1) > > enum { > SIL24_HOST_BAR = 0, > SIL24_PORT_BAR = 2, > > - /* sil24 fetches in chunks of 64bytes. The first block > - * contains the PRB and two SGEs. From the second block, it's > - * consisted of four SGEs and called SGT. Calculate the > - * number of SGTs that fit into one page. > - */ > - SIL24_PRB_SZ = sizeof(struct sil24_prb) > - + 2 * sizeof(struct sil24_sge), > - SIL24_MAX_SGT = (PAGE_SIZE - SIL24_PRB_SZ) > - / (4 * sizeof(struct sil24_sge)), > - > - /* This will give us one unused SGEs for ATA. This extra SGE > - * will be used to store CDB for ATAPI devices. > - */ > - SIL24_MAX_SGE = 4 * SIL24_MAX_SGT + 1, > - > /* > * Global controller registers (128 bytes @ BAR0) > */ > @@ -244,13 +243,13 @@ enum { > > struct sil24_ata_block { > struct sil24_prb prb; > - struct sil24_sge sge[SIL24_MAX_SGE]; > + struct sil24_sge sge[]; > }; > > struct sil24_atapi_block { > struct sil24_prb prb; > u8 cdb[16]; > - struct sil24_sge sge[SIL24_MAX_SGE]; > + struct sil24_sge sge[]; > }; > > union sil24_cmd_block { > @@ -373,7 +372,7 @@ static struct pci_driver sil24_pci_driver = { > #endif > }; > > -static const struct scsi_host_template sil24_sht = { > +static DEFINE_GLOBAL_PAGE_SIZE_VAR_CONST(struct scsi_host_template, sil24_sht, { > __ATA_BASE_SHT(DRV_NAME), > .can_queue = SIL24_MAX_CMDS, > .sg_tablesize = SIL24_MAX_SGE, > @@ -382,7 +381,7 @@ static const struct scsi_host_template sil24_sht = { > .sdev_groups = ata_ncq_sdev_groups, > .change_queue_depth = ata_scsi_change_queue_depth, > .device_configure = ata_scsi_device_configure > -}; > +}); > > static struct ata_port_operations sil24_ops = { > .inherits = &sata_pmp_port_ops, > @@ -1193,7 +1192,7 @@ 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 = sizeof(*cb) * SIL24_MAX_CMDS; > + size_t cb_size = PAGE_SIZE * SIL24_MAX_CMDS; > dma_addr_t cb_dma; > > pp = devm_kzalloc(dev, sizeof(*pp), GFP_KERNEL); > @@ -1258,7 +1257,6 @@ static void sil24_init_controller(struct ata_host *host) > > static int sil24_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) > { > - extern int __MARKER__sil24_cmd_block_is_sized_wrongly; > struct ata_port_info pi = sil24_port_info[ent->driver_data]; > const struct ata_port_info *ppi[] = { &pi, NULL }; > void __iomem * const *iomap; > @@ -1266,9 +1264,9 @@ static int sil24_init_one(struct pci_dev *pdev, const struct pci_device_id *ent) > int rc; > u32 tmp; > > - /* cause link error if sil24_cmd_block is sized wrongly */ > - if (sizeof(union sil24_cmd_block) != PAGE_SIZE) > - __MARKER__sil24_cmd_block_is_sized_wrongly = 1; > + /* union sil24_cmd_block must be PAGE_SIZE */ > + 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); > > ata_print_version_once(&pdev->dev, DRV_VERSION); > > -- > 2.43.0 > As you might know, there is an effort to annotate all flexible array members with their run-time size information, see commit: dd06e72e68bc ("Compiler Attributes: Add __counted_by macro") I haven't looked at the DEFINE_GLOBAL_PAGE_SIZE_VAR_CONST macro, but since sge[] now becomes a flexible array member, I think it would be nice if it would be possible to somehow use the __counted_by macro. Other than that, this looks good to me. Kind regards, Niklas
