Patch "staging: unisys: visorhba: fix s-Par to boot with option CONFIG_VMAP_STACK set to y" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

staging: unisys: visorhba: fix s-Par to boot with option CONFIG_VMAP_STACK set to y

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
staging-unisys-visorhba-fix-s-par-to-boot-with-option-config_vmap_stack-set-to-y.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Sameer Wadgaonkar <[email protected]>
Date: Tue, 18 Apr 2017 16:55:25 -0400
Subject: staging: unisys: visorhba: fix s-Par to boot with option CONFIG_VMAP_STACK set to y

From: Sameer Wadgaonkar <[email protected]>

[ 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.

---
 drivers/staging/unisys/visorhba/visorhba_main.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

@@ -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 *cm
 		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 *cm
 		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 *cm
 			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) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/staging-unisys-visorhba-fix-s-par-to-boot-with-option-config_vmap_stack-set-to-y.patch