[libata ahci, qstor] fix miscount of scatter/gather entries

Don't directly reference qc->n_elem, as that might cause an off-by-one
error for misaligned (padded) ATAPI transfers.

diff --git a/drivers/scsi/ahci.c b/drivers/scsi/ahci.c
index 57ef7ae..7b0640b 100644 (file)
--- a/drivers/scsi/ahci.c
+++ b/drivers/scsi/ahci.c
@@ -474,11 +474,12 @@ static void ahci_tf_read(struct ata_port *ap, struct ata_taskfile *tf)
        ata_tf_from_fis(d2h_fis, tf);
 }
 
-static void ahci_fill_sg(struct ata_queued_cmd *qc)
+static unsigned int ahci_fill_sg(struct ata_queued_cmd *qc)
 {
        struct ahci_port_priv *pp = qc->ap->private_data;
        struct scatterlist *sg;
        struct ahci_sg *ahci_sg;
+       unsigned int n_sg = 0;
 
        VPRINTK("ENTER\n");
 
@@ -493,8 +494,12 @@ static void ahci_fill_sg(struct ata_queued_cmd *qc)
                ahci_sg->addr = cpu_to_le32(addr & 0xffffffff);
                ahci_sg->addr_hi = cpu_to_le32((addr >> 16) >> 16);
                ahci_sg->flags_size = cpu_to_le32(sg_len - 1);
+
                ahci_sg++;
+               n_sg++;
        }
+
+       return n_sg;
 }
 
 static void ahci_qc_prep(struct ata_queued_cmd *qc)
@@ -503,13 +508,14 @@ static void ahci_qc_prep(struct ata_queued_cmd *qc)
        struct ahci_port_priv *pp = ap->private_data;
        u32 opts;
        const u32 cmd_fis_len = 5; /* five dwords */
+       unsigned int n_elem;
 
        /*
         * Fill in command slot information (currently only one slot,
         * slot 0, is currently since we don't do queueing)
         */
 
-       opts = (qc->n_elem << 16) | cmd_fis_len;
+       opts = cmd_fis_len;
        if (qc->tf.flags & ATA_TFLAG_WRITE)
                opts |= AHCI_CMD_WRITE;
        if (is_atapi_taskfile(&qc->tf))
@@ -533,7 +539,9 @@ static void ahci_qc_prep(struct ata_queued_cmd *qc)
        if (!(qc->flags & ATA_QCFLAG_DMAMAP))
                return;
 
-       ahci_fill_sg(qc);
+       n_elem = ahci_fill_sg(qc);
+
+       pp->cmd_slot[0].opts |= cpu_to_le32(n_elem << 16);
 }
 
 static void ahci_intr_error(struct ata_port *ap, u32 irq_stat)

diff --git a/drivers/scsi/sata_qstor.c b/drivers/scsi/sata_qstor.c
index b2f6324..4a6d306 100644 (file)
--- a/drivers/scsi/sata_qstor.c
+++ b/drivers/scsi/sata_qstor.c
@@ -268,7 +268,7 @@ static void qs_scr_write (struct ata_port *ap, unsigned int sc_reg, u32 val)
        writel(val, (void __iomem *)(ap->ioaddr.scr_addr + (sc_reg * 8)));
 }
 
-static void qs_fill_sg(struct ata_queued_cmd *qc)
+static unsigned int qs_fill_sg(struct ata_queued_cmd *qc)
 {
        struct scatterlist *sg;
        struct ata_port *ap = qc->ap;
@@ -296,6 +296,8 @@ static void qs_fill_sg(struct ata_queued_cmd *qc)
                                        (unsigned long long)addr, len);
                nelem++;
        }
+
+       return nelem;
 }
 
 static void qs_qc_prep(struct ata_queued_cmd *qc)
@@ -304,6 +306,7 @@ static void qs_qc_prep(struct ata_queued_cmd *qc)
        u8 dflags = QS_DF_PORD, *buf = pp->pkt;
        u8 hflags = QS_HF_DAT | QS_HF_IEN | QS_HF_VLD;
        u64 addr;
+       unsigned int nelem;
 
        VPRINTK("ENTER\n");
 
@@ -313,7 +316,7 @@ static void qs_qc_prep(struct ata_queued_cmd *qc)
                return;
        }
 
-       qs_fill_sg(qc);
+       nelem = qs_fill_sg(qc);
 
        if ((qc->tf.flags & ATA_TFLAG_WRITE))
                hflags |= QS_HF_DIRO;
@@ -324,7 +327,7 @@ static void qs_qc_prep(struct ata_queued_cmd *qc)
        buf[ 0] = QS_HCB_HDR;
        buf[ 1] = hflags;
        *(__le32 *)(&buf[ 4]) = cpu_to_le32(qc->nsect * ATA_SECT_SIZE);
-       *(__le32 *)(&buf[ 8]) = cpu_to_le32(qc->n_elem);
+       *(__le32 *)(&buf[ 8]) = cpu_to_le32(nelem);
        addr = ((u64)pp->pkt_dma) + QS_CPB_BYTES;
        *(__le64 *)(&buf[16]) = cpu_to_le64(addr);