| Message ID | 1653035003-70312-4-git-send-email-john.garry@huawei.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | DMA mapping changes for SCSI core | expand |
Hi John,
url: https://github.com/intel-lab-lkp/linux/commits/John-Garry/DMA-mapping-changes-for-SCSI-core/20220520-163049
base: https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git next
config: s390-randconfig-m031-20220519 (https://download.01.org/0day-ci/archive/20220521/202205210545.gkS834ds-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 11.3.0
If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
smatch warnings:
drivers/scsi/hosts.c:243 scsi_add_host_with_dma() warn: variable dereferenced before check 'dma_dev' (see line 228)
vim +/dma_dev +243 drivers/scsi/hosts.c
d139b9bd0e52dd James Bottomley 2009-11-05 209 int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
d139b9bd0e52dd James Bottomley 2009-11-05 210 struct device *dma_dev)
^1da177e4c3f41 Linus Torvalds 2005-04-16 211 {
^1da177e4c3f41 Linus Torvalds 2005-04-16 212 struct scsi_host_template *sht = shost->hostt;
^1da177e4c3f41 Linus Torvalds 2005-04-16 213 int error = -EINVAL;
^1da177e4c3f41 Linus Torvalds 2005-04-16 214
91921e016a2199 Hannes Reinecke 2014-06-25 215 shost_printk(KERN_INFO, shost, "%s\n",
^1da177e4c3f41 Linus Torvalds 2005-04-16 216 sht->info ? sht->info(shost) : sht->name);
^1da177e4c3f41 Linus Torvalds 2005-04-16 217
^1da177e4c3f41 Linus Torvalds 2005-04-16 218 if (!shost->can_queue) {
91921e016a2199 Hannes Reinecke 2014-06-25 219 shost_printk(KERN_ERR, shost,
91921e016a2199 Hannes Reinecke 2014-06-25 220 "can_queue = 0 no longer supported\n");
542bd1377a9630 James Bottomley 2008-04-21 221 goto fail;
^1da177e4c3f41 Linus Torvalds 2005-04-16 222 }
^1da177e4c3f41 Linus Torvalds 2005-04-16 223
50b6cb3516365c Dexuan Cui 2021-10-07 224 /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
50b6cb3516365c Dexuan Cui 2021-10-07 225 shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
ea2f0f77538c50 John Garry 2021-05-19 226 shost->can_queue);
ea2f0f77538c50 John Garry 2021-05-19 227
2ad7ba6ca08593 John Garry 2022-05-20 @228 if (dma_dev->dma_mask) {
^^^^^^^^^^^^^^^^^
The patch adds a new unchecked dereference
2ad7ba6ca08593 John Garry 2022-05-20 229 shost->max_sectors = min_t(unsigned int, shost->max_sectors,
2ad7ba6ca08593 John Garry 2022-05-20 230 dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT);
2ad7ba6ca08593 John Garry 2022-05-20 231 }
2ad7ba6ca08593 John Garry 2022-05-20 232
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03 233 error = scsi_init_sense_cache(shost);
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03 234 if (error)
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03 235 goto fail;
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03 236
d285203cf647d7 Christoph Hellwig 2014-01-17 237 error = scsi_mq_setup_tags(shost);
542bd1377a9630 James Bottomley 2008-04-21 238 if (error)
542bd1377a9630 James Bottomley 2008-04-21 239 goto fail;
d285203cf647d7 Christoph Hellwig 2014-01-17 240
^1da177e4c3f41 Linus Torvalds 2005-04-16 241 if (!shost->shost_gendev.parent)
^1da177e4c3f41 Linus Torvalds 2005-04-16 242 shost->shost_gendev.parent = dev ? dev : &platform_bus;
3c8d9a957d0ae6 James Bottomley 2012-05-04 @243 if (!dma_dev)
^^^^^^^^
The old code checked for NULL
3c8d9a957d0ae6 James Bottomley 2012-05-04 244 dma_dev = shost->shost_gendev.parent;
3c8d9a957d0ae6 James Bottomley 2012-05-04 245
d139b9bd0e52dd James Bottomley 2009-11-05 246 shost->dma_dev = dma_dev;
^1da177e4c3f41 Linus Torvalds 2005-04-16 247
5c6fab9d558470 Mika Westerberg 2016-02-18 248 /*
5c6fab9d558470 Mika Westerberg 2016-02-18 249 * Increase usage count temporarily here so that calling
5c6fab9d558470 Mika Westerberg 2016-02-18 250 * scsi_autopm_put_host() will trigger runtime idle if there is
5c6fab9d558470 Mika Westerberg 2016-02-18 251 * nothing else preventing suspending the device.
5c6fab9d558470 Mika Westerberg 2016-02-18 252 */
5c6fab9d558470 Mika Westerberg 2016-02-18 253 pm_runtime_get_noresume(&shost->shost_gendev);
bc4f24014de58f Alan Stern 2010-06-17 254 pm_runtime_set_active(&shost->shost_gendev);
bc4f24014de58f Alan Stern 2010-06-17 255 pm_runtime_enable(&shost->shost_gendev);
bc4f24014de58f Alan Stern 2010-06-17 256 device_enable_async_suspend(&shost->shost_gendev);
bc4f24014de58f Alan Stern 2010-06-17 257
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index f69b77cbf538..a3ae6345473b 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -225,6 +225,11 @@ int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev, shost->cmd_per_lun = min_t(int, shost->cmd_per_lun, shost->can_queue); + if (dma_dev->dma_mask) { + shost->max_sectors = min_t(unsigned int, shost->max_sectors, + dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT); + } + error = scsi_init_sense_cache(shost); if (error) goto fail; diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 8d18cc7e510e..2d43bb8799bd 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1884,10 +1884,6 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q) blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize); } - if (dev->dma_mask) { - shost->max_sectors = min_t(unsigned int, shost->max_sectors, - dma_max_mapping_size(dev) >> SECTOR_SHIFT); - } blk_queue_max_hw_sectors(q, shost->max_sectors); blk_queue_segment_boundary(q, shost->dma_boundary); dma_set_seg_boundary(dev, shost->dma_boundary);
Streaming DMA mappings may be considerably slower when mappings go through an IOMMU and the total mapping length is somewhat long. This is because the IOMMU IOVA code allocates and free an IOVA for each mapping, which may affect performance. For performance reasons set the request_queue max_sectors from dma_opt_mapping_size(), which knows this mapping limit. In addition, the shost->max_sectors is repeatedly set for each sdev in __scsi_init_queue(). This is unnecessary, so set once when adding the host. Signed-off-by: John Garry <john.garry@huawei.com> --- drivers/scsi/hosts.c | 5 +++++ drivers/scsi/scsi_lib.c | 4 ---- 2 files changed, 5 insertions(+), 4 deletions(-)