[PATCH AUTOSEL for 4.4 058/101] staging: unisys: visorhba: fix s-Par to boot with option CONFIG_VMAP_STACK set to y

Sasha Levin
2018-03-08T05:01:55Z

From: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com>

[ Upstream commit 3c2bf0bd08123f3497bd3e84bd9088c937b0cb40 ]

The root issue is that we are not allowed to have items on the
stack being passed to "DMA" like operations. In this case we have
a vmcall and an inline completion of scsi command.

This patch fixes the issue by moving the variables on stack in
do_scsi_nolinuxstat() to heap memory.

Signed-off-by: Sameer Wadgaonkar <sameer.wadgaonkar@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
drivers/staging/unisys/visorhba/visorhba_main.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/unisys/visorhba/visorhba_main.c b/drivers/staging/unisys/visorhba/visorhba_main.c
index c119f20dfd44..3f2ccf9d7358 100644
--- a/drivers/staging/unisys/visorhba/visorhba_main.c
+++ b/drivers/staging/unisys/visorhba/visorhba_main.c
@@ -792,7 +792,7 @@ static void
do_scsi_nolinuxstat(struct uiscmdrsp *cmdrsp, struct scsi_cmnd *scsicmd)
{
struct scsi_device *scsidev;
- unsigned char buf[36];
+ unsigned char *buf;
struct scatterlist *sg;
unsigned int i;
char *this_page;
@@ -807,6 +807,10 @@ do_scsi_nolinuxstat(struct uiscmdrsp *cmdrsp, struct scsi_cmnd *scsicmd)
if (cmdrsp->scsi.no_disk_result == 0)
return;

+ buf = kzalloc(sizeof(char) * 36, GFP_KERNEL);
+ if (!buf)
+ return;
+
/* Linux scsi code wants a device at Lun 0
* to issue report luns, but we don't want
* a disk there so we'll present a processor
@@ -820,6 +824,7 @@ do_scsi_nolinuxstat(struct uiscmdrsp *cmdrsp, struct scsi_cmnd *scsicmd)
if (scsi_sg_count(scsicmd) == 0) {
memcpy(scsi_sglist(scsicmd), buf,
cmdrsp->scsi.bufflen);
+ kfree(buf);
return;
}

@@ -831,6 +836,7 @@ do_scsi_nolinuxstat(struct uiscmdrsp *cmdrsp, struct scsi_cmnd *scsicmd)
memcpy(this_page, buf + bufind, sg[i].length);
kunmap_atomic(this_page_orig);
}
+ kfree(buf);
} else {
devdata = (struct visorhba_devdata *)scsidev->host->hostdata;
for_each_vdisk_match(vdisk, devdata, scsidev) {
--
2.14.1