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authorMing Lei <ming.lei@redhat.com>2019-06-06 11:34:10 +0300
committerMartin K. Petersen <martin.petersen@oracle.com>2019-06-20 22:21:33 +0300
commitee5a1dbfec57cc1ffdedf2bd767c84d5e0498ed8 (patch)
tree77dac02b6d46221a4e909842fdb175833a299853 /drivers/scsi/esp_scsi.c
parent0e9fdd2b315c0fde535336ea09499a927e415566 (diff)
downloadlinux-ee5a1dbfec57cc1ffdedf2bd767c84d5e0498ed8.tar.xz
scsi: esp: use sg helper to iterate over scatterlist
Unlike the legacy I/O path, scsi-mq preallocates a large array to hold the scatterlist for each request. This static allocation can consume substantial amounts of memory on modern controllers which support a large number of concurrently outstanding requests. To facilitate a switch to a smaller static allocation combined with a dynamic allocation for requests that need it, we need to make sure all SCSI drivers handle chained scatterlists correctly. Convert remaining drivers that directly dereference the scatterlist array to using the iterator functions. [mkp: clarified commit message] Cc: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Ewan D. Milne <emilne@redhat.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Finn Thain <fthain@telegraphics.com.au> Cc: Guenter Roeck <linux@roeck-us.net> Reported-by: Guenter Roeck <linux@roeck-us.net> Tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/esp_scsi.c')
-rw-r--r--drivers/scsi/esp_scsi.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 76fd02ccbf49..1e3ea9dc74d2 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -370,6 +370,7 @@ static void esp_map_dma(struct esp *esp, struct scsi_cmnd *cmd)
struct esp_cmd_priv *spriv = ESP_CMD_PRIV(cmd);
struct scatterlist *sg = scsi_sglist(cmd);
int total = 0, i;
+ struct scatterlist *s;
if (cmd->sc_data_direction == DMA_NONE)
return;
@@ -380,16 +381,18 @@ static void esp_map_dma(struct esp *esp, struct scsi_cmnd *cmd)
* a dma address, so perform an identity mapping.
*/
spriv->num_sg = scsi_sg_count(cmd);
- for (i = 0; i < spriv->num_sg; i++) {
- sg[i].dma_address = (uintptr_t)sg_virt(&sg[i]);
- total += sg_dma_len(&sg[i]);
+
+ scsi_for_each_sg(cmd, s, spriv->num_sg, i) {
+ s->dma_address = (uintptr_t)sg_virt(s);
+ total += sg_dma_len(s);
}
} else {
spriv->num_sg = scsi_dma_map(cmd);
- for (i = 0; i < spriv->num_sg; i++)
- total += sg_dma_len(&sg[i]);
+ scsi_for_each_sg(cmd, s, spriv->num_sg, i)
+ total += sg_dma_len(s);
}
spriv->cur_residue = sg_dma_len(sg);
+ spriv->prv_sg = NULL;
spriv->cur_sg = sg;
spriv->tot_residue = total;
}
@@ -443,7 +446,8 @@ static void esp_advance_dma(struct esp *esp, struct esp_cmd_entry *ent,
p->tot_residue = 0;
}
if (!p->cur_residue && p->tot_residue) {
- p->cur_sg++;
+ p->prv_sg = p->cur_sg;
+ p->cur_sg = sg_next(p->cur_sg);
p->cur_residue = sg_dma_len(p->cur_sg);
}
}
@@ -464,6 +468,7 @@ static void esp_save_pointers(struct esp *esp, struct esp_cmd_entry *ent)
return;
}
ent->saved_cur_residue = spriv->cur_residue;
+ ent->saved_prv_sg = spriv->prv_sg;
ent->saved_cur_sg = spriv->cur_sg;
ent->saved_tot_residue = spriv->tot_residue;
}
@@ -478,6 +483,7 @@ static void esp_restore_pointers(struct esp *esp, struct esp_cmd_entry *ent)
return;
}
spriv->cur_residue = ent->saved_cur_residue;
+ spriv->prv_sg = ent->saved_prv_sg;
spriv->cur_sg = ent->saved_cur_sg;
spriv->tot_residue = ent->saved_tot_residue;
}
@@ -1646,7 +1652,7 @@ static int esp_msgin_process(struct esp *esp)
spriv = ESP_CMD_PRIV(ent->cmd);
if (spriv->cur_residue == sg_dma_len(spriv->cur_sg)) {
- spriv->cur_sg--;
+ spriv->cur_sg = spriv->prv_sg;
spriv->cur_residue = 1;
} else
spriv->cur_residue++;