diff options
Diffstat (limited to 'drivers/usb/storage/protocol.c')
| -rw-r--r-- | drivers/usb/storage/protocol.c | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/drivers/usb/storage/protocol.c b/drivers/usb/storage/protocol.c index a41ce21c069..958f5b17847 100644 --- a/drivers/usb/storage/protocol.c +++ b/drivers/usb/storage/protocol.c @@ -150,13 +150,14 @@ void usb_stor_transparent_scsi_command(struct scsi_cmnd *srb, /* Copy a buffer of length buflen to/from the srb's transfer buffer. * Update the **sgptr and *offset variables so that the next copy will - * pick up from where this one left off. */ - + * pick up from where this one left off. + */ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer, unsigned int buflen, struct scsi_cmnd *srb, struct scatterlist **sgptr, unsigned int *offset, enum xfer_buf_dir dir) { unsigned int cnt; + struct scatterlist *sg = *sgptr; /* We have to go through the list one entry * at a time. Each s-g entry contains some number of pages, and @@ -164,22 +165,23 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer, * in kernel-addressable memory then kmap() will return its address. * If the page is not directly accessible -- such as a user buffer * located in high memory -- then kmap() will map it to a temporary - * position in the kernel's virtual address space. */ - struct scatterlist *sg = *sgptr; + * position in the kernel's virtual address space. + */ if (!sg) sg = scsi_sglist(srb); + buflen = min(buflen, scsi_bufflen(srb)); /* This loop handles a single s-g list entry, which may - * include multiple pages. Find the initial page structure - * and the starting offset within the page, and update - * the *offset and **sgptr values for the next loop. */ + * include multiple pages. Find the initial page structure + * and the starting offset within the page, and update + * the *offset and **sgptr values for the next loop. + */ cnt = 0; - while (cnt < buflen) { + while (cnt < buflen && sg) { struct page *page = sg_page(sg) + ((sg->offset + *offset) >> PAGE_SHIFT); - unsigned int poff = - (sg->offset + *offset) & (PAGE_SIZE-1); + unsigned int poff = (sg->offset + *offset) & (PAGE_SIZE-1); unsigned int sglen = sg->length - *offset; if (sglen > buflen - cnt) { @@ -222,14 +224,15 @@ unsigned int usb_stor_access_xfer_buf(unsigned char *buffer, } /* Store the contents of buffer into srb's transfer buffer and set the - * SCSI residue. */ + * SCSI residue. + */ void usb_stor_set_xfer_buf(unsigned char *buffer, unsigned int buflen, struct scsi_cmnd *srb) { unsigned int offset = 0; struct scatterlist *sg = NULL; - usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset, + buflen = usb_stor_access_xfer_buf(buffer, buflen, srb, &sg, &offset, TO_XFER_BUF); if (buflen < scsi_bufflen(srb)) scsi_set_resid(srb, scsi_bufflen(srb) - buflen); |