# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1200915811 0
# Node ID 7070d34f251c3e0c411022a5d365aea9804114a7
# Parent 77f831cbb91ddca3a7539fa9197d4abc2d2bfcf9
blkback/blktap: Check for kthread_should_stop() in inner loop,
mdelaay() should be msleep(), and these changes belong in blktap as
well as blkback.
Based on comments and patches from Jan Beulich and Steven Smith.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
drivers/xen/blkback/blkback.c | 10 ++++++++--
drivers/xen/blktap/blktap.c | 15 ++++++++++++++-
2 files changed, 22 insertions(+), 3 deletions(-)
diff -r 77f831cbb91d -r 7070d34f251c drivers/xen/blkback/blkback.c
--- a/drivers/xen/blkback/blkback.c Fri Jan 18 16:52:25 2008 +0000
+++ b/drivers/xen/blkback/blkback.c Mon Jan 21 11:43:31 2008 +0000
@@ -312,7 +312,7 @@ static int do_block_io_op(blkif_t *blkif
rp = blk_rings->common.sring->req_prod;
rmb(); /* Ensure we see queued requests up to 'rp'. */
- while ((rc != rp)) {
+ while (rc != rp) {
if (RING_REQUEST_CONS_OVERFLOW(&blk_rings->common, rc))
break;
@@ -320,6 +320,11 @@ static int do_block_io_op(blkif_t *blkif
pending_req = alloc_req();
if (NULL == pending_req) {
blkif->st_oo_req++;
+ more_to_do = 1;
+ break;
+ }
+
+ if (kthread_should_stop()) {
more_to_do = 1;
break;
}
@@ -354,7 +359,7 @@ static int do_block_io_op(blkif_t *blkif
default:
/* A good sign something is wrong: sleep for a while to
* avoid excessive CPU consumption by a bad guest. */
- mdelay(1);
+ msleep(1);
DPRINTK("error: unknown block io operation [%d]\n",
req.operation);
make_response(blkif, req.id, req.operation,
@@ -517,6 +522,7 @@ static void dispatch_rw_block_io(blkif_t
fail_response:
make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR);
free_req(pending_req);
+ msleep(1); /* back off a bit */
}
diff -r 77f831cbb91d -r 7070d34f251c drivers/xen/blktap/blktap.c
--- a/drivers/xen/blktap/blktap.c Fri Jan 18 16:52:25 2008 +0000
+++ b/drivers/xen/blktap/blktap.c Mon Jan 21 11:43:31 2008 +0000
@@ -52,6 +52,7 @@
#include <linux/major.h>
#include <linux/gfp.h>
#include <linux/poll.h>
+#include <linux/delay.h>
#include <asm/tlbflush.h>
#define MAX_TAP_DEV 256 /*the maximum number of tapdisk ring devices */
@@ -1242,6 +1243,11 @@ static int do_block_io_op(blkif_t *blkif
break;
}
+ if (kthread_should_stop()) {
+ more_to_do = 1;
+ break;
+ }
+
switch (blkif->blk_protocol) {
case BLKIF_PROTOCOL_NATIVE:
memcpy(&req, RING_GET_REQUEST(&blk_rings->native, rc),
@@ -1270,6 +1276,9 @@ static int do_block_io_op(blkif_t *blkif
break;
default:
+ /* A good sign something is wrong: sleep for a while to
+ * avoid excessive CPU consumption by a bad guest. */
+ msleep(1);
WPRINTK("unknown operation [%d]\n",
req.operation);
make_response(blkif, req.id, req.operation,
@@ -1277,6 +1286,9 @@ static int do_block_io_op(blkif_t *blkif
free_req(pending_req);
break;
}
+
+ /* Yield point for this unbounded loop. */
+ cond_resched();
}
blktap_kick_user(blkif->dev_num);
@@ -1503,7 +1515,8 @@ static void dispatch_rw_block_io(blkif_t
fail_response:
make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR);
free_req(pending_req);
-}
+ msleep(1); /* back off a bit */
+}
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