[PATCH 4.4 21/53] scsi: sg: disable SET_FORCE_LOW_DMA

Greg Kroah-Hartman
2018-01-22T08:40:13Z

From: Hannes Reinecke <hare@suse.de>

commit 745dfa0d8ec26b24f3304459ff6e9eacc5c8351b upstream.

The ioctl SET_FORCE_LOW_DMA has never worked since the initial git
check-in, and the respective setting is nowadays handled correctly. So
disable it entirely.

Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Tested-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/sg.c | 30 +++++++++---------------------
include/scsi/sg.h | 1 -
2 files changed, 9 insertions(+), 22 deletions(-)

--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -160,7 +160,6 @@ typedef struct sg_fd { /* holds the sta
struct list_head rq_list; /* head of request list */
struct fasync_struct *async_qp; /* used by asynchronous notification */
Sg_request req_arr[SG_MAX_QUEUE]; /* used as singly-linked list */
- char low_dma; /* as in parent but possibly overridden to 1 */
char force_packid; /* 1 -> pack_id input to read(), 0 -> ignored */
char cmd_q; /* 1 -> allow command queuing, 0 -> don't */
unsigned char next_cmd_len; /* 0: automatic, >0: use on next write() */
@@ -932,24 +931,14 @@ sg_ioctl(struct file *filp, unsigned int
/* strange ..., for backward compatibility */
return sfp->timeout_user;
case SG_SET_FORCE_LOW_DMA:
- result = get_user(val, ip);
- if (result)
- return result;
- if (val) {
- sfp->low_dma = 1;
- if ((0 == sfp->low_dma) && !sfp->res_in_use) {
- val = (int) sfp->reserve.bufflen;
- sg_remove_scat(sfp, &sfp->reserve);
- sg_build_reserve(sfp, val);
- }
- } else {
- if (atomic_read(&sdp->detaching))
- return -ENODEV;
- sfp->low_dma = sdp->device->host->unchecked_isa_dma;
- }
+ /*
+ * N.B. This ioctl never worked properly, but failed to
+ * return an error value. So returning '0' to keep compability
+ * with legacy applications.
+ */
return 0;
case SG_GET_LOW_DMA:
- return put_user((int) sfp->low_dma, ip);
+ return put_user((int) sdp->device->host->unchecked_isa_dma, ip);
case SG_GET_SCSI_ID:
if (!access_ok(VERIFY_WRITE, p, sizeof (sg_scsi_id_t)))
return -EFAULT;
@@ -1870,6 +1859,7 @@ sg_build_indirect(Sg_scatter_hold * schp
int sg_tablesize = sfp->parentdp->sg_tablesize;
int blk_size = buff_size, order;
gfp_t gfp_mask = GFP_ATOMIC | __GFP_COMP | __GFP_NOWARN;
+ struct sg_device *sdp = sfp->parentdp;

if (blk_size < 0)
return -EFAULT;
@@ -1895,7 +1885,7 @@ sg_build_indirect(Sg_scatter_hold * schp
scatter_elem_sz_prev = num;
}

- if (sfp->low_dma)
+ if (sdp->device->host->unchecked_isa_dma)
gfp_mask |= GFP_DMA;

if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SYS_RAWIO))
@@ -2158,8 +2148,6 @@ sg_add_sfp(Sg_device * sdp)
sfp->timeout = SG_DEFAULT_TIMEOUT;
sfp->timeout_user = SG_DEFAULT_TIMEOUT_USER;
sfp->force_packid = SG_DEF_FORCE_PACK_ID;
- sfp->low_dma = (SG_DEF_FORCE_LOW_DMA == 0) ?
- sdp->device->host->unchecked_isa_dma : 1;
sfp->cmd_q = SG_DEF_COMMAND_Q;
sfp->keep_orphan = SG_DEF_KEEP_ORPHAN;
sfp->parentdp = sdp;
@@ -2618,7 +2606,7 @@ static void sg_proc_debug_helper(struct
jiffies_to_msecs(fp->timeout),
fp->reserve.bufflen,
(int) fp->reserve.k_use_sg,
- (int) fp->low_dma);
+ (int) sdp->device->host->unchecked_isa_dma);
seq_printf(s, " cmd_q=%d f_packid=%d k_orphan=%d closed=0\n",
(int) fp->cmd_q, (int) fp->force_packid,
(int) fp->keep_orphan);
--- a/include/scsi/sg.h
+++ b/include/scsi/sg.h
@@ -197,7 +197,6 @@ typedef struct sg_req_info { /* used by
#define SG_DEFAULT_RETRIES 0

/* Defaults, commented if they differ from original sg driver */
-#define SG_DEF_FORCE_LOW_DMA 0 /* was 1 -> memory below 16MB on i386 */
#define SG_DEF_FORCE_PACK_ID 0
#define SG_DEF_KEEP_ORPHAN 0
#define SG_DEF_RESERVED_SIZE SG_SCATTER_SZ /* load time option */