This is a note to let you know that I've just added the patch titled
xen/blkfront: read response from backend only once
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:
xen-blkfront-read-response-from-backend-only-once.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 <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Mon Nov 29 07:12:46 PM CET 2021
From: Juergen Gross <jgross@xxxxxxxx>
Date: Mon, 29 Nov 2021 13:46:12 +0100
Subject: xen/blkfront: read response from backend only once
From: Juergen Gross <jgross@xxxxxxxx>
commit 71b66243f9898d0e54296b4e7035fb33cdcb0707 upstream.
In order to avoid problems in case the backend is modifying a response
on the ring page while the frontend has already seen it, just read the
response into a local buffer in one go and then operate on that buffer
only.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210730103854.12681-2-jgross@xxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/xen-blkfront.c | 35 ++++++++++++++++++-----------------
1 file changed, 18 insertions(+), 17 deletions(-)
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1296,7 +1296,7 @@ static void blkif_completion(struct blk_
static irqreturn_t blkif_interrupt(int irq, void *dev_id)
{
struct request *req;
- struct blkif_response *bret;
+ struct blkif_response bret;
RING_IDX i, rp;
unsigned long flags;
struct blkfront_info *info = (struct blkfront_info *)dev_id;
@@ -1316,8 +1316,9 @@ static irqreturn_t blkif_interrupt(int i
for (i = info->ring.rsp_cons; i != rp; i++) {
unsigned long id;
- bret = RING_GET_RESPONSE(&info->ring, i);
- id = bret->id;
+ RING_COPY_RESPONSE(&info->ring, i, &bret);
+ id = bret.id;
+
/*
* The backend has messed up and given us an id that we would
* never have given to it (we stamp it up to BLK_RING_SIZE -
@@ -1325,29 +1326,29 @@ static irqreturn_t blkif_interrupt(int i
*/
if (id >= BLK_RING_SIZE(info)) {
WARN(1, "%s: response to %s has incorrect id (%ld)\n",
- info->gd->disk_name, op_name(bret->operation), id);
+ info->gd->disk_name, op_name(bret.operation), id);
/* We can't safely get the 'struct request' as
* the id is busted. */
continue;
}
req = info->shadow[id].request;
- if (bret->operation != BLKIF_OP_DISCARD)
- blkif_completion(&info->shadow[id], info, bret);
+ if (bret.operation != BLKIF_OP_DISCARD)
+ blkif_completion(&info->shadow[id], info, &bret);
if (add_id_to_freelist(info, id)) {
WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
- info->gd->disk_name, op_name(bret->operation), id);
+ info->gd->disk_name, op_name(bret.operation), id);
continue;
}
- error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
- switch (bret->operation) {
+ error = (bret.status == BLKIF_RSP_OKAY) ? 0 : -EIO;
+ switch (bret.operation) {
case BLKIF_OP_DISCARD:
- if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
+ if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
struct request_queue *rq = info->rq;
printk(KERN_WARNING "blkfront: %s: %s op failed\n",
- info->gd->disk_name, op_name(bret->operation));
+ info->gd->disk_name, op_name(bret.operation));
error = -EOPNOTSUPP;
info->feature_discard = 0;
info->feature_secdiscard = 0;
@@ -1358,15 +1359,15 @@ static irqreturn_t blkif_interrupt(int i
break;
case BLKIF_OP_FLUSH_DISKCACHE:
case BLKIF_OP_WRITE_BARRIER:
- if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
+ if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
printk(KERN_WARNING "blkfront: %s: %s op failed\n",
- info->gd->disk_name, op_name(bret->operation));
+ info->gd->disk_name, op_name(bret.operation));
error = -EOPNOTSUPP;
}
- if (unlikely(bret->status == BLKIF_RSP_ERROR &&
+ if (unlikely(bret.status == BLKIF_RSP_ERROR &&
info->shadow[id].req.u.rw.nr_segments == 0)) {
printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
- info->gd->disk_name, op_name(bret->operation));
+ info->gd->disk_name, op_name(bret.operation));
error = -EOPNOTSUPP;
}
if (unlikely(error)) {
@@ -1378,9 +1379,9 @@ static irqreturn_t blkif_interrupt(int i
/* fall through */
case BLKIF_OP_READ:
case BLKIF_OP_WRITE:
- if (unlikely(bret->status != BLKIF_RSP_OKAY))
+ if (unlikely(bret.status != BLKIF_RSP_OKAY))
dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
- "request: %x\n", bret->status);
+ "request: %x\n", bret.status);
blk_mq_complete_request(req, error);
break;
Patches currently in stable-queue which might be from jgross@xxxxxxxx are
queue-4.4/xen-blkfront-read-response-from-backend-only-once.patch
queue-4.4/tty-hvc-replace-bug_on-with-negative-return-value.patch
queue-4.4/xen-blkfront-don-t-trust-the-backend-response-data-blindly.patch
queue-4.4/xen-sync-include-xen-interface-io-ring.h-with-xen-s-newest-version.patch
queue-4.4/xen-blkfront-don-t-take-local-copy-of-a-request-from-the-ring-page.patch
queue-4.4/xen-detect-uninitialized-xenbus-in-xenbus_init.patch
queue-4.4/xen-netfront-don-t-read-data-from-request-on-the-ring-page.patch
queue-4.4/xen-netfront-disentangle-tx_skb_freelist.patch
queue-4.4/xen-netfront-read-response-from-backend-only-once.patch
queue-4.4/xen-netfront-don-t-trust-the-backend-response-data-blindly.patch
