Re: [bug] ata subsystem related crash with latest -git

Jeff Garzik
2007-10-18T09:32:41Z

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Jens Axboe wrote:
> The sata_mv construct looks a bit odd. Does this work? That last

The sata_mv construct worked just fine before sg chaining :)

> end_mv_sg test should always be true, just being paranoid...
>
> diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
> index 4df8311..5397eea 100644
> --- a/drivers/ata/sata_mv.c
> +++ b/drivers/ata/sata_mv.c
> @@ -1138,8 +1138,9 @@ static void mv_fill_sg(struct ata_queued_cmd *qc)
> {
> struct mv_port_priv *pp = qc->ap->private_data;
> struct scatterlist *sg;
> - struct mv_sg *mv_sg;
> + struct mv_sg *mv_sg, *end_mv_sg;
>
> + end_mv_sg = NULL;
> mv_sg = pp->sg_tbl;
> ata_for_each_sg(sg, qc) {
> dma_addr_t addr = sg_dma_address(sg);
> @@ -1158,14 +1159,12 @@ static void mv_fill_sg(struct ata_queued_cmd *qc)
>
> sg_len -= len;
> addr += len;
> -
> - if (!sg_len && ata_sg_is_last(sg, qc))
> - mv_sg->flags_size |= cpu_to_le32(EPRD_FLAG_END_OF_TBL);
> -
> + end_mv_sg = mv_sg;
> mv_sg++;
> }
> -
> }
> + if (end_mv_sg)
> + end_mv_sg->flags_size |= cpu_to_le32(EPRD_FLAG_END_OF_TBL);
> }
>

I'm testing a similar patch based on ata_fill_sg()'s method, which
basically does something similar to what you've done here (see
attached). I had noticed that ata_fill_sg() did not call ata_sg_is_last().

If this fixes the problem, I think the best solution would be to delete
ata_sg_is_last(). In the few users that exist, we should be able to
eliminate the test programmatically as you and ata_fill_sg() have done
-- thereby eliminating a branch per loop in a hotpath.

Off to test the attached... if that doesn't work I'll try your version,
though there shouldn't be much difference.

Jeff

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diff --git a/drivers/ata/sata_mv.c b/drivers/ata/sata_mv.c
index 4df8311..42b5a9e 100644
--- a/drivers/ata/sata_mv.c
+++ b/drivers/ata/sata_mv.c
@@ -421,7 +421,6 @@ static void mv_error_handler(struct ata_port *ap);
static void mv_post_int_cmd(struct ata_queued_cmd *qc);
static void mv_eh_freeze(struct ata_port *ap);
static void mv_eh_thaw(struct ata_port *ap);
-static int mv_slave_config(struct scsi_device *sdev);
static int mv_init_one(struct pci_dev *pdev, const struct pci_device_id *ent);

static void mv5_phy_errata(struct mv_host_priv *hpriv, void __iomem *mmio,
@@ -459,7 +458,7 @@ static struct scsi_host_template mv5_sht = {
.use_clustering = 1,
.proc_name = DRV_NAME,
.dma_boundary = MV_DMA_BOUNDARY,
- .slave_configure = mv_slave_config,
+ .slave_configure = ata_scsi_slave_config,
.slave_destroy = ata_scsi_slave_destroy,
.bios_param = ata_std_bios_param,
};
@@ -477,7 +476,7 @@ static struct scsi_host_template mv6_sht = {
.use_clustering = 1,
.proc_name = DRV_NAME,
.dma_boundary = MV_DMA_BOUNDARY,
- .slave_configure = mv_slave_config,
+ .slave_configure = ata_scsi_slave_config,
.slave_destroy = ata_scsi_slave_destroy,
.bios_param = ata_std_bios_param,
};
@@ -756,17 +755,6 @@ static void mv_irq_clear(struct ata_port *ap)
{
}

-static int mv_slave_config(struct scsi_device *sdev)
-{
- int rc = ata_scsi_slave_config(sdev);
- if (rc)
- return rc;
-
- blk_queue_max_phys_segments(sdev->request_queue, MV_MAX_SG_CT / 2);
-
- return 0; /* scsi layer doesn't check return value, sigh */
-}
-
static void mv_set_edma_ptrs(void __iomem *port_mmio,
struct mv_host_priv *hpriv,
struct mv_port_priv *pp)
@@ -1138,34 +1126,35 @@ static void mv_fill_sg(struct ata_queued_cmd *qc)
{
struct mv_port_priv *pp = qc->ap->private_data;
struct scatterlist *sg;
- struct mv_sg *mv_sg;
+ struct mv_sg *mv_sg = pp->sg_tbl;
+ unsigned int idx = 0;

- mv_sg = pp->sg_tbl;
ata_for_each_sg(sg, qc) {
- dma_addr_t addr = sg_dma_address(sg);
- u32 sg_len = sg_dma_len(sg);
+ u64 addr;
+ u32 offset, sg_len, len;
+
+ addr = sg_dma_address(sg);
+ sg_len = sg_dma_len(sg);

while (sg_len) {
- u32 offset = addr & 0xffff;
- u32 len = sg_len;
+ offset = addr & 0xffff;
+ len = sg_len;

if ((offset + sg_len > 0x10000))
len = 0x10000 - offset;

- mv_sg->addr = cpu_to_le32(addr & 0xffffffff);
- mv_sg->addr_hi = cpu_to_le32((addr >> 16) >> 16);
- mv_sg->flags_size = cpu_to_le32(len & 0xffff);
+ mv_sg[idx].addr = cpu_to_le32(addr & 0xffffffff);
+ mv_sg[idx].addr_hi = cpu_to_le32(addr >> 32);
+ mv_sg[idx].flags_size = cpu_to_le32(len & 0xffff);

+ idx++;
sg_len -= len;
addr += len;
-
- if (!sg_len && ata_sg_is_last(sg, qc))
- mv_sg->flags_size |= cpu_to_le32(EPRD_FLAG_END_OF_TBL);
-
- mv_sg++;
}
-
}
+
+ if (idx)
+ mv_sg[idx - 1].flags_size |= cpu_to_le32(EPRD_FLAG_END_OF_TBL);
}

static inline void mv_crqb_pack_cmd(__le16 *cmdw, u8 data, u8 addr, unsigned last)