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authorDouglas Gilbert <dgilbert@interlog.com>2016-05-31 17:15:07 -0400
committerMartin K. Petersen <martin.petersen@oracle.com>2016-07-12 23:16:31 -0400
commitfb0cc8d1c1881c56683123ff129452e88fdf5575 (patch)
tree7df3e14ae2d4446d67b2a129f99081bd96dcc2d4 /drivers
parentbaa6719f902af9c03e528b08dfb847de295b5137 (diff)
downloadlinux-fb0cc8d1c1881c56683123ff129452e88fdf5575.tar.bz2
scsi_debug: fix sleep in invalid context
In this post: http://www.spinics.net/lists/linux-scsi/msg97124.html the author shows some kernel infrastructure complaining about a sleep in an invalid context. Remove offending call to vmalloc(). Instead of using kzalloc() which reviewers didn't like, use a bucket system (64 bytes on the stack) and potentially multiple calls to sg_pcopy_from_buffer() to construct the 'data-in' buffer for the SCSI REPORT LUNS command. Signed-off-by: Douglas Gilbert <dgilbert@interlog.com> Acked-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/scsi/scsi_debug.c93
1 files changed, 66 insertions, 27 deletions
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 0f9ba41e27d8..6a219a0844d3 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -890,7 +890,7 @@ static int make_ua(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
return 0;
}
-/* Returns 0 if ok else (DID_ERROR << 16). Sets scp->resid . */
+/* Build SCSI "data-in" buffer. Returns 0 if ok else (DID_ERROR << 16). */
static int fill_from_dev_buffer(struct scsi_cmnd *scp, unsigned char *arr,
int arr_len)
{
@@ -909,7 +909,35 @@ static int fill_from_dev_buffer(struct scsi_cmnd *scp, unsigned char *arr,
return 0;
}
-/* Returns number of bytes fetched into 'arr' or -1 if error. */
+/* Partial build of SCSI "data-in" buffer. Returns 0 if ok else
+ * (DID_ERROR << 16). Can write to offset in data-in buffer. If multiple
+ * calls, not required to write in ascending offset order. Assumes resid
+ * set to scsi_bufflen() prior to any calls.
+ */
+static int p_fill_from_dev_buffer(struct scsi_cmnd *scp, const void *arr,
+ int arr_len, unsigned int off_dst)
+{
+ int act_len, n;
+ struct scsi_data_buffer *sdb = scsi_in(scp);
+ off_t skip = off_dst;
+
+ if (sdb->length <= off_dst)
+ return 0;
+ if (!(scsi_bidi_cmnd(scp) || scp->sc_data_direction == DMA_FROM_DEVICE))
+ return DID_ERROR << 16;
+
+ act_len = sg_pcopy_from_buffer(sdb->table.sgl, sdb->table.nents,
+ arr, arr_len, skip);
+ pr_debug("%s: off_dst=%u, scsi_bufflen=%u, act_len=%u, resid=%d\n",
+ __func__, off_dst, scsi_bufflen(scp), act_len, sdb->resid);
+ n = (int)scsi_bufflen(scp) - ((int)off_dst + act_len);
+ sdb->resid = min(sdb->resid, n);
+ return 0;
+}
+
+/* Fetches from SCSI "data-out" buffer. Returns number of bytes fetched into
+ * 'arr' or -1 if error.
+ */
static int fetch_to_dev_buffer(struct scsi_cmnd *scp, unsigned char *arr,
int arr_len)
{
@@ -3269,6 +3297,8 @@ static int resp_get_lba_status(struct scsi_cmnd *scp,
return fill_from_dev_buffer(scp, arr, SDEBUG_GET_LBA_STATUS_LEN);
}
+#define RL_BUCKET_ELEMS 8
+
/* Even though each pseudo target has a REPORT LUNS "well known logical unit"
* (W-LUN), the normal Linux scanning logic does not associate it with a
* device (e.g. /dev/sg7). The following magic will make that association:
@@ -3285,12 +3315,14 @@ static int resp_report_luns(struct scsi_cmnd *scp,
unsigned char select_report;
u64 lun;
struct scsi_lun *lun_p;
- u8 *arr;
+ u8 arr[RL_BUCKET_ELEMS * sizeof(struct scsi_lun)];
unsigned int lun_cnt; /* normal LUN count (max: 256) */
unsigned int wlun_cnt; /* report luns W-LUN count */
unsigned int tlun_cnt; /* total LUN count */
unsigned int rlen; /* response length (in bytes) */
- int i, res;
+ int k, j, n, res;
+ unsigned int off_rsp = 0;
+ const int sz_lun = sizeof(struct scsi_lun);
clear_luns_changed_on_target(devip);
@@ -3329,33 +3361,40 @@ static int resp_report_luns(struct scsi_cmnd *scp,
--lun_cnt;
tlun_cnt = lun_cnt + wlun_cnt;
-
- rlen = (tlun_cnt * sizeof(struct scsi_lun)) + 8;
- arr = vmalloc(rlen);
- if (!arr) {
- mk_sense_buffer(scp, ILLEGAL_REQUEST, INSUFF_RES_ASC,
- INSUFF_RES_ASCQ);
- return check_condition_result;
- }
- memset(arr, 0, rlen);
+ rlen = tlun_cnt * sz_lun; /* excluding 8 byte header */
+ scsi_set_resid(scp, scsi_bufflen(scp));
pr_debug("select_report %d luns = %d wluns = %d no_lun0 %d\n",
select_report, lun_cnt, wlun_cnt, sdebug_no_lun_0);
- /* luns start at byte 8 in response following the header */
- lun_p = (struct scsi_lun *)&arr[8];
-
- /* LUNs use single level peripheral device addressing method */
+ /* loops rely on sizeof response header same as sizeof lun (both 8) */
lun = sdebug_no_lun_0 ? 1 : 0;
- for (i = 0; i < lun_cnt; i++)
- int_to_scsilun(lun++, lun_p++);
-
- if (wlun_cnt)
- int_to_scsilun(SCSI_W_LUN_REPORT_LUNS, lun_p++);
-
- put_unaligned_be32(rlen - 8, &arr[0]);
-
- res = fill_from_dev_buffer(scp, arr, rlen);
- vfree(arr);
+ for (k = 0, j = 0, res = 0; true; ++k, j = 0) {
+ memset(arr, 0, sizeof(arr));
+ lun_p = (struct scsi_lun *)&arr[0];
+ if (k == 0) {
+ put_unaligned_be32(rlen, &arr[0]);
+ ++lun_p;
+ j = 1;
+ }
+ for ( ; j < RL_BUCKET_ELEMS; ++j, ++lun_p) {
+ if ((k * RL_BUCKET_ELEMS) + j > lun_cnt)
+ break;
+ int_to_scsilun(lun++, lun_p);
+ }
+ if (j < RL_BUCKET_ELEMS)
+ break;
+ n = j * sz_lun;
+ res = p_fill_from_dev_buffer(scp, arr, n, off_rsp);
+ if (res)
+ return res;
+ off_rsp += n;
+ }
+ if (wlun_cnt) {
+ int_to_scsilun(SCSI_W_LUN_REPORT_LUNS, lun_p);
+ ++j;
+ }
+ if (j > 0)
+ res = p_fill_from_dev_buffer(scp, arr, j * sz_lun, off_rsp);
return res;
}