Replace the use of llist with list.
llist_for_each_entry_safe can trigger a bug in GCC 4.1, so it's best
to remove it and use a doubly linked list, which is used extensively
in the kernel already.
Specifically this bug can be triggered by hot-unplugging a disk,
either by doing xm block-detach or by save/restore cycle.
BUG: unable to handle kernel paging request at fffffffffffffff0
IP: [<ffffffffa0047223>] blkif_free+0x63/0x130 [xen_blkfront]
The crash call trace is:
...
bad_area_nosemaphore+0x13/0x20
do_page_fault+0x25e/0x4b0
page_fault+0x25/0x30
? blkif_free+0x63/0x130 [xen_blkfront]
blkfront_resume+0x46/0xa0 [xen_blkfront]
xenbus_dev_resume+0x6c/0x140
pm_op+0x192/0x1b0
device_resume+0x82/0x1e0
dpm_resume+0xc9/0x1a0
dpm_resume_end+0x15/0x30
do_suspend+0x117/0x1e0
When drilling down to the assembler code, on newer GCC it does
.L29:
cmpq $-16, %r12 #, persistent_gnt check
je .L30 #, out of the loop
.L25:
... code in the loop
testq %r13, %r13 # n
je .L29 #, back to the top of the loop
cmpq $-16, %r12 #, persistent_gnt check
movq 16(%r12), %r13 # <variable>.node.next, n
jne .L25 #, back to the top of the loop
.L30:
While on GCC 4.1, it is:
L78:
... code in the loop
testq %r13, %r13 # n
je .L78 #, back to the top of the loop
movq 16(%rbx), %r13 # <variable>.node.next, n
jmp .L78 #, back to the top of the loop
Which basically means that the exit loop condition instead of
being:
&(pos)->member != NULL;
is:
;
which makes the loop unbound.
Since we always manipulate the list while holding the io_lock, there's
no need for additional locking (llist used previously is safe to use
concurrently without additional locking).
Should be backported to 3.8 stable.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
[Part of the description]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: xen-devel@lists.xen.org
---
drivers/block/xen-blkfront.c | 41 ++++++++++++++++++-----------------------
1 files changed, 18 insertions(+), 23 deletions(-)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 9620644..97324cd1 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -44,7 +44,7 @@
#include <linux/mutex.h>
#include <linux/scatterlist.h>
#include <linux/bitmap.h>
-#include <linux/llist.h>
+#include <linux/list.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
@@ -68,7 +68,7 @@ enum blkif_state {
struct grant {
grant_ref_t gref;
unsigned long pfn;
- struct llist_node node;
+ struct list_head node;
};
struct blk_shadow {
@@ -105,7 +105,7 @@ struct blkfront_info
struct work_struct work;
struct gnttab_free_callback callback;
struct blk_shadow shadow[BLK_RING_SIZE];
- struct llist_head persistent_gnts;
+ struct list_head persistent_gnts;
unsigned int persistent_gnts_c;
unsigned long shadow_free;
unsigned int feature_flush;
@@ -371,10 +371,11 @@ static int blkif_queue_request(struct request *req)
lsect = fsect + (sg->length >> 9) - 1;
if (info->persistent_gnts_c) {
- BUG_ON(llist_empty(&info->persistent_gnts));
- gnt_list_entry = llist_entry(
- llist_del_first(&info->persistent_gnts),
- struct grant, node);
+ BUG_ON(list_empty(&info->persistent_gnts));
+ gnt_list_entry = list_first_entry(
+ &info->persistent_gnts,
+ struct grant, node);
+ list_del(&gnt_list_entry->node);
ref = gnt_list_entry->gref;
buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
@@ -790,9 +791,8 @@ static void blkif_restart_queue(struct work_struct *work)
static void blkif_free(struct blkfront_info *info, int suspend)
{
- struct llist_node *all_gnts;
- struct grant *persistent_gnt, *tmp;
- struct llist_node *n;
+ struct grant *persistent_gnt;
+ struct grant *n;
/* Prevent new requests being issued until we fix things up. */
spin_lock_irq(&info->io_lock);
@@ -804,20 +804,15 @@ static void blkif_free(struct blkfront_info *info, int
suspend)
/* Remove all persistent grants */
if (info->persistent_gnts_c) {
- all_gnts = llist_del_all(&info->persistent_gnts);
- persistent_gnt = llist_entry(all_gnts, typeof(*(persistent_gnt)), node);
- while (persistent_gnt) {
+ list_for_each_entry_safe(persistent_gnt, n,
+ &info->persistent_gnts, node) {
+ list_del(&persistent_gnt->node);
gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
__free_page(pfn_to_page(persistent_gnt->pfn));
- tmp = persistent_gnt;
- n = persistent_gnt->node.next;
- if (n)
- persistent_gnt = llist_entry(n, typeof(*(persistent_gnt)), node);
- else
- persistent_gnt = NULL;
- kfree(tmp);
+ kfree(persistent_gnt);
+ info->persistent_gnts_c--;
}
- info->persistent_gnts_c = 0;
+ BUG_ON(info->persistent_gnts_c != 0);
}
/* No more gnttab callback work. */
@@ -875,7 +870,7 @@ static void blkif_completion(struct blk_shadow *s, struct
blkfront_info *info,
}
/* Add the persistent grant into the list of free grants */
for (i = 0; i < s->req.u.rw.nr_segments; i++) {
- llist_add(&s->grants_used[i]->node, &info->persistent_gnts);
+ list_add(&s->grants_used[i]->node, &info->persistent_gnts);
info->persistent_gnts_c++;
}
}
@@ -1171,7 +1166,7 @@ static int blkfront_probe(struct xenbus_device *dev,
spin_lock_init(&info->io_lock);
info->xbdev = dev;
info->vdevice = vdevice;
- init_llist_head(&info->persistent_gnts);
+ INIT_LIST_HEAD(&info->persistent_gnts);
info->persistent_gnts_c = 0;
info->connected = BLKIF_STATE_DISCONNECTED;
INIT_WORK(&info->work, blkif_restart_queue);
--
1.7.7.5 (Apple Git-26)
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
Konrad Rzeszutek Wilk
2013-Mar-19 12:51 UTC
Re: [PATCH 3/5] xen-blkfront: switch from llist to list
On Mon, Mar 18, 2013 at 05:49:34PM +0100, Roger Pau Monne wrote:> Replace the use of llist with list. > > llist_for_each_entry_safe can trigger a bug in GCC 4.1, so it''s best > to remove it and use a doubly linked list, which is used extensively > in the kernel already. > > Specifically this bug can be triggered by hot-unplugging a disk, > either by doing xm block-detach or by save/restore cycle. > > BUG: unable to handle kernel paging request at fffffffffffffff0 > IP: [<ffffffffa0047223>] blkif_free+0x63/0x130 [xen_blkfront] > The crash call trace is: > ... > bad_area_nosemaphore+0x13/0x20 > do_page_fault+0x25e/0x4b0 > page_fault+0x25/0x30 > ? blkif_free+0x63/0x130 [xen_blkfront] > blkfront_resume+0x46/0xa0 [xen_blkfront] > xenbus_dev_resume+0x6c/0x140 > pm_op+0x192/0x1b0 > device_resume+0x82/0x1e0 > dpm_resume+0xc9/0x1a0 > dpm_resume_end+0x15/0x30 > do_suspend+0x117/0x1e0 > > When drilling down to the assembler code, on newer GCC it does > .L29: > cmpq $-16, %r12 #, persistent_gnt check > je .L30 #, out of the loop > .L25: > ... code in the loop > testq %r13, %r13 # n > je .L29 #, back to the top of the loop > cmpq $-16, %r12 #, persistent_gnt check > movq 16(%r12), %r13 # <variable>.node.next, n > jne .L25 #, back to the top of the loop > .L30: > > While on GCC 4.1, it is: > L78: > ... code in the loop > testq %r13, %r13 # n > je .L78 #, back to the top of the loop > movq 16(%rbx), %r13 # <variable>.node.next, n > jmp .L78 #, back to the top of the loop > > Which basically means that the exit loop condition instead of > being: > > &(pos)->member != NULL; > > is: > ; > > which makes the loop unbound. > > Since we always manipulate the list while holding the io_lock, there''s > no need for additional locking (llist used previously is safe to use > concurrently without additional locking). > > Should be backported to 3.8 stable.I get konrad@phenom:~/linux$ patch -p1 < /tmp/kk patching file drivers/block/xen-blkfront.c Hunk #1 FAILED at 44. Hunk #2 FAILED at 68. Hunk #3 FAILED at 105. Hunk #4 FAILED at 371. patch: **** malformed patch at line 172: ork) and idea why? Could you resent the patch as an attachment please?> > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > [Part of the description] > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Cc: xen-devel@lists.xen.org > --- > drivers/block/xen-blkfront.c | 41 ++++++++++++++++++----------------------- > 1 files changed, 18 insertions(+), 23 deletions(-) > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index 9620644..97324cd1 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -44,7 +44,7 @@ > #include <linux/mutex.h> > #include <linux/scatterlist.h> > #include <linux/bitmap.h> > -#include <linux/llist.h> > +#include <linux/list.h> > > #include <xen/xen.h> > #include <xen/xenbus.h> > @@ -68,7 +68,7 @@ enum blkif_state { > struct grant { > grant_ref_t gref; > unsigned long pfn; > - struct llist_node node; > + struct list_head node; > }; > > struct blk_shadow { > @@ -105,7 +105,7 @@ struct blkfront_info > struct work_struct work; > struct gnttab_free_callback callback; > struct blk_shadow shadow[BLK_RING_SIZE]; > - struct llist_head persistent_gnts; > + struct list_head persistent_gnts; > unsigned int persistent_gnts_c; > unsigned long shadow_free; > unsigned int feature_flush; > @@ -371,10 +371,11 @@ static int blkif_queue_request(struct request *req) > lsect = fsect + (sg->length >> 9) - 1; > > if (info->persistent_gnts_c) { > - BUG_ON(llist_empty(&info->persistent_gnts)); > - gnt_list_entry = llist_entry( > - llist_del_first(&info->persistent_gnts), > - struct grant, node); > + BUG_ON(list_empty(&info->persistent_gnts)); > + gnt_list_entry = list_first_entry( > + &info->persistent_gnts, > + struct grant, node); > + list_del(&gnt_list_entry->node); > > ref = gnt_list_entry->gref; > buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); > @@ -790,9 +791,8 @@ static void blkif_restart_queue(struct work_struct *work) > > static void blkif_free(struct blkfront_info *info, int suspend) > { > - struct llist_node *all_gnts; > - struct grant *persistent_gnt, *tmp; > - struct llist_node *n; > + struct grant *persistent_gnt; > + struct grant *n; > > /* Prevent new requests being issued until we fix things up. */ > spin_lock_irq(&info->io_lock); > @@ -804,20 +804,15 @@ static void blkif_free(struct blkfront_info *info, int suspend) > > /* Remove all persistent grants */ > if (info->persistent_gnts_c) { > - all_gnts = llist_del_all(&info->persistent_gnts); > - persistent_gnt = llist_entry(all_gnts, typeof(*(persistent_gnt)), node); > - while (persistent_gnt) { > + list_for_each_entry_safe(persistent_gnt, n, > + &info->persistent_gnts, node) { > + list_del(&persistent_gnt->node); > gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); > __free_page(pfn_to_page(persistent_gnt->pfn)); > - tmp = persistent_gnt; > - n = persistent_gnt->node.next; > - if (n) > - persistent_gnt = llist_entry(n, typeof(*(persistent_gnt)), node); > - else > - persistent_gnt = NULL; > - kfree(tmp); > + kfree(persistent_gnt); > + info->persistent_gnts_c--; > } > - info->persistent_gnts_c = 0; > + BUG_ON(info->persistent_gnts_c != 0); > } > > /* No more gnttab callback work. */ > @@ -875,7 +870,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, > } > /* Add the persistent grant into the list of free grants */ > for (i = 0; i < s->req.u.rw.nr_segments; i++) { > - llist_add(&s->grants_used[i]->node, &info->persistent_gnts); > + list_add(&s->grants_used[i]->node, &info->persistent_gnts); > info->persistent_gnts_c++; > } > } > @@ -1171,7 +1166,7 @@ static int blkfront_probe(struct xenbus_device *dev, > spin_lock_init(&info->io_lock); > info->xbdev = dev; > info->vdevice = vdevice; > - init_llist_head(&info->persistent_gnts); > + INIT_LIST_HEAD(&info->persistent_gnts); > info->persistent_gnts_c = 0; > info->connected = BLKIF_STATE_DISCONNECTED; > INIT_WORK(&info->work, blkif_restart_queue); > -- > 1.7.7.5 (Apple Git-26) >
Roger Pau Monné
2013-Mar-19 12:57 UTC
Re: [PATCH 3/5] xen-blkfront: switch from llist to list
On 19/03/13 13:51, Konrad Rzeszutek Wilk wrote:> On Mon, Mar 18, 2013 at 05:49:34PM +0100, Roger Pau Monne wrote: >> Replace the use of llist with list. >> >> llist_for_each_entry_safe can trigger a bug in GCC 4.1, so it''s best >> to remove it and use a doubly linked list, which is used extensively >> in the kernel already. >> >> Specifically this bug can be triggered by hot-unplugging a disk, >> either by doing xm block-detach or by save/restore cycle. >> >> BUG: unable to handle kernel paging request at fffffffffffffff0 >> IP: [<ffffffffa0047223>] blkif_free+0x63/0x130 [xen_blkfront] >> The crash call trace is: >> ... >> bad_area_nosemaphore+0x13/0x20 >> do_page_fault+0x25e/0x4b0 >> page_fault+0x25/0x30 >> ? blkif_free+0x63/0x130 [xen_blkfront] >> blkfront_resume+0x46/0xa0 [xen_blkfront] >> xenbus_dev_resume+0x6c/0x140 >> pm_op+0x192/0x1b0 >> device_resume+0x82/0x1e0 >> dpm_resume+0xc9/0x1a0 >> dpm_resume_end+0x15/0x30 >> do_suspend+0x117/0x1e0 >> >> When drilling down to the assembler code, on newer GCC it does >> .L29: >> cmpq $-16, %r12 #, persistent_gnt check >> je .L30 #, out of the loop >> .L25: >> ... code in the loop >> testq %r13, %r13 # n >> je .L29 #, back to the top of the loop >> cmpq $-16, %r12 #, persistent_gnt check >> movq 16(%r12), %r13 # <variable>.node.next, n >> jne .L25 #, back to the top of the loop >> .L30: >> >> While on GCC 4.1, it is: >> L78: >> ... code in the loop >> testq %r13, %r13 # n >> je .L78 #, back to the top of the loop >> movq 16(%rbx), %r13 # <variable>.node.next, n >> jmp .L78 #, back to the top of the loop >> >> Which basically means that the exit loop condition instead of >> being: >> >> &(pos)->member != NULL; >> >> is: >> ; >> >> which makes the loop unbound. >> >> Since we always manipulate the list while holding the io_lock, there''s >> no need for additional locking (llist used previously is safe to use >> concurrently without additional locking). >> >> Should be backported to 3.8 stable. > > I get > konrad@phenom:~/linux$ patch -p1 < /tmp/kk > patching file drivers/block/xen-blkfront.c > Hunk #1 FAILED at 44. > Hunk #2 FAILED at 68. > Hunk #3 FAILED at 105. > Hunk #4 FAILED at 371. > patch: **** malformed patch at line 172: ork) > > > and idea why? Could you resent the patch as an attachment please?Strange, I''ve used git send-email. I''ve attached it, but you can also get them from: http://xenbits.xen.org/gitweb/?p=people/royger/linux.git;a=shortlog;h=refs/heads/blk-for-3.9 --------------020902000804020804080109 Content-Type: text/plain; charset="UTF-8"; x-mac-type=0; x-mac-creator=0; name="0003-xen-blkfront-switch-from-llist-to-list.patch" Content-Transfer-Encoding: 8bit Content-Disposition: attachment; filename="0003-xen-blkfront-switch-from-llist-to-list.patch" From 59a1e9b3ec1cbae76a8ee2ad142255d5d1fc1ae1 Mon Sep 17 00:00:00 2001 From: Roger Pau Monne <roger.pau@citrix.com> Date: Mon, 25 Feb 2013 10:49:10 +0100 Subject: [PATCH 3/5] xen-blkfront: switch from llist to list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Replace the use of llist with list. llist_for_each_entry_safe can trigger a bug in GCC 4.1, so it''s best to remove it and use a doubly linked list, which is used extensively in the kernel already. Specifically this bug can be triggered by hot-unplugging a disk, either by doing xm block-detach or by save/restore cycle. BUG: unable to handle kernel paging request at fffffffffffffff0 IP: [<ffffffffa0047223>] blkif_free+0x63/0x130 [xen_blkfront] The crash call trace is: ... bad_area_nosemaphore+0x13/0x20 do_page_fault+0x25e/0x4b0 page_fault+0x25/0x30 ? blkif_free+0x63/0x130 [xen_blkfront] blkfront_resume+0x46/0xa0 [xen_blkfront] xenbus_dev_resume+0x6c/0x140 pm_op+0x192/0x1b0 device_resume+0x82/0x1e0 dpm_resume+0xc9/0x1a0 dpm_resume_end+0x15/0x30 do_suspend+0x117/0x1e0 When drilling down to the assembler code, on newer GCC it does .L29: cmpq $-16, %r12 #, persistent_gnt check je .L30 #, out of the loop .L25: ... code in the loop testq %r13, %r13 # n je .L29 #, back to the top of the loop cmpq $-16, %r12 #, persistent_gnt check movq 16(%r12), %r13 # <variable>.node.next, n jne .L25 #, back to the top of the loop .L30: While on GCC 4.1, it is: L78: ... code in the loop testq %r13, %r13 # n je .L78 #, back to the top of the loop movq 16(%rbx), %r13 # <variable>.node.next, n jmp .L78 #, back to the top of the loop Which basically means that the exit loop condition instead of being: &(pos)->member != NULL; is: ; which makes the loop unbound. Since we always manipulate the list while holding the io_lock, there''s no need for additional locking (llist used previously is safe to use concurrently without additional locking). Should be backported to 3.8 stable. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> [Part of the description] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: xen-devel@lists.xen.org --- drivers/block/xen-blkfront.c | 41 ++++++++++++++++++----------------------- 1 files changed, 18 insertions(+), 23 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 9620644..97324cd1 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -44,7 +44,7 @@ #include <linux/mutex.h> #include <linux/scatterlist.h> #include <linux/bitmap.h> -#include <linux/llist.h> +#include <linux/list.h> #include <xen/xen.h> #include <xen/xenbus.h> @@ -68,7 +68,7 @@ enum blkif_state { struct grant { grant_ref_t gref; unsigned long pfn; - struct llist_node node; + struct list_head node; }; struct blk_shadow { @@ -105,7 +105,7 @@ struct blkfront_info struct work_struct work; struct gnttab_free_callback callback; struct blk_shadow shadow[BLK_RING_SIZE]; - struct llist_head persistent_gnts; + struct list_head persistent_gnts; unsigned int persistent_gnts_c; unsigned long shadow_free; unsigned int feature_flush; @@ -371,10 +371,11 @@ static int blkif_queue_request(struct request *req) lsect = fsect + (sg->length >> 9) - 1; if (info->persistent_gnts_c) { - BUG_ON(llist_empty(&info->persistent_gnts)); - gnt_list_entry = llist_entry( - llist_del_first(&info->persistent_gnts), - struct grant, node); + BUG_ON(list_empty(&info->persistent_gnts)); + gnt_list_entry = list_first_entry( + &info->persistent_gnts, + struct grant, node); + list_del(&gnt_list_entry->node); ref = gnt_list_entry->gref; buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); @@ -790,9 +791,8 @@ static void blkif_restart_queue(struct work_struct *work) static void blkif_free(struct blkfront_info *info, int suspend) { - struct llist_node *all_gnts; - struct grant *persistent_gnt, *tmp; - struct llist_node *n; + struct grant *persistent_gnt; + struct grant *n; /* Prevent new requests being issued until we fix things up. */ spin_lock_irq(&info->io_lock); @@ -804,20 +804,15 @@ static void blkif_free(struct blkfront_info *info, int suspend) /* Remove all persistent grants */ if (info->persistent_gnts_c) { - all_gnts = llist_del_all(&info->persistent_gnts); - persistent_gnt = llist_entry(all_gnts, typeof(*(persistent_gnt)), node); - while (persistent_gnt) { + list_for_each_entry_safe(persistent_gnt, n, + &info->persistent_gnts, node) { + list_del(&persistent_gnt->node); gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); __free_page(pfn_to_page(persistent_gnt->pfn)); - tmp = persistent_gnt; - n = persistent_gnt->node.next; - if (n) - persistent_gnt = llist_entry(n, typeof(*(persistent_gnt)), node); - else - persistent_gnt = NULL; - kfree(tmp); + kfree(persistent_gnt); + info->persistent_gnts_c--; } - info->persistent_gnts_c = 0; + BUG_ON(info->persistent_gnts_c != 0); } /* No more gnttab callback work. */ @@ -875,7 +870,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, } /* Add the persistent grant into the list of free grants */ for (i = 0; i < s->req.u.rw.nr_segments; i++) { - llist_add(&s->grants_used[i]->node, &info->persistent_gnts); + list_add(&s->grants_used[i]->node, &info->persistent_gnts); info->persistent_gnts_c++; } } @@ -1171,7 +1166,7 @@ static int blkfront_probe(struct xenbus_device *dev, spin_lock_init(&info->io_lock); info->xbdev = dev; info->vdevice = vdevice; - init_llist_head(&info->persistent_gnts); + INIT_LIST_HEAD(&info->persistent_gnts); info->persistent_gnts_c = 0; info->connected = BLKIF_STATE_DISCONNECTED; INIT_WORK(&info->work, blkif_restart_queue); -- 1.7.7.5 (Apple Git-26) --------------020902000804020804080109 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel --------------020902000804020804080109--
Konrad Rzeszutek Wilk
2013-Mar-19 14:31 UTC
Re: [PATCH 3/5] xen-blkfront: switch from llist to list
On Mon, Mar 18, 2013 at 05:49:34PM +0100, Roger Pau Monne wrote:> Replace the use of llist with list. >I applied this patch, but I changed the git commit to be: commit 155b7edb51430a280f86c1e21b7be308b0d219d4 Author: Roger Pau Monne <roger.pau@citrix.com> Date: Mon Mar 18 17:49:34 2013 +0100 xen-blkfront: switch from llist to list The git commit f84adf4921ae3115502f44ff467b04bf2f88cf04 (xen-blkfront: drop the use of llist_for_each_entry_safe) was a stop-gate to fix a GCC4.1 bug. The appropiate way is to actually use an list instead of using an llist. As such this patch replaces the usage of llist with an list. Since we always manipulate the list while holding the io_lock, there''s no need for additional locking (llist used previously is safe to use concurrently without additional locking). Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> CC: stable@vger.kernel.org [v1: Redid the git commit description] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 9620644..97324cd1 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -44,7 +44,7 @@ #include <linux/mutex.h> #include <linux/scatterlist.h> #include <linux/bitmap.h> -#include <linux/llist.h> +#include <linux/list.h> #include <xen/xen.h> #include <xen/xenbus.h> @@ -68,7 +68,7 @@ enum blkif_state { struct grant { grant_ref_t gref; unsigned long pfn; - struct llist_node node; + struct list_head node; }; struct blk_shadow { @@ -105,7 +105,7 @@ struct blkfront_info struct work_struct work; struct gnttab_free_callback callback; struct blk_shadow shadow[BLK_RING_SIZE]; - struct llist_head persistent_gnts; + struct list_head persistent_gnts; unsigned int persistent_gnts_c; unsigned long shadow_free; unsigned int feature_flush; @@ -371,10 +371,11 @@ static int blkif_queue_request(struct request *req) lsect = fsect + (sg->length >> 9) - 1; if (info->persistent_gnts_c) { - BUG_ON(llist_empty(&info->persistent_gnts)); - gnt_list_entry = llist_entry( - llist_del_first(&info->persistent_gnts), - struct grant, node); + BUG_ON(list_empty(&info->persistent_gnts)); + gnt_list_entry = list_first_entry( + &info->persistent_gnts, + struct grant, node); + list_del(&gnt_list_entry->node); ref = gnt_list_entry->gref; buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); @@ -790,9 +791,8 @@ static void blkif_restart_queue(struct work_struct *work) static void blkif_free(struct blkfront_info *info, int suspend) { - struct llist_node *all_gnts; - struct grant *persistent_gnt, *tmp; - struct llist_node *n; + struct grant *persistent_gnt; + struct grant *n; /* Prevent new requests being issued until we fix things up. */ spin_lock_irq(&info->io_lock); @@ -804,20 +804,15 @@ static void blkif_free(struct blkfront_info *info, int suspend) /* Remove all persistent grants */ if (info->persistent_gnts_c) { - all_gnts = llist_del_all(&info->persistent_gnts); - persistent_gnt = llist_entry(all_gnts, typeof(*(persistent_gnt)), node); - while (persistent_gnt) { + list_for_each_entry_safe(persistent_gnt, n, + &info->persistent_gnts, node) { + list_del(&persistent_gnt->node); gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); __free_page(pfn_to_page(persistent_gnt->pfn)); - tmp = persistent_gnt; - n = persistent_gnt->node.next; - if (n) - persistent_gnt = llist_entry(n, typeof(*(persistent_gnt)), node); - else - persistent_gnt = NULL; - kfree(tmp); + kfree(persistent_gnt); + info->persistent_gnts_c--; } - info->persistent_gnts_c = 0; + BUG_ON(info->persistent_gnts_c != 0); } /* No more gnttab callback work. */ @@ -875,7 +870,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, } /* Add the persistent grant into the list of free grants */ for (i = 0; i < s->req.u.rw.nr_segments; i++) { - llist_add(&s->grants_used[i]->node, &info->persistent_gnts); + list_add(&s->grants_used[i]->node, &info->persistent_gnts); info->persistent_gnts_c++; } } @@ -1171,7 +1166,7 @@ static int blkfront_probe(struct xenbus_device *dev, spin_lock_init(&info->io_lock); info->xbdev = dev; info->vdevice = vdevice; - init_llist_head(&info->persistent_gnts); + INIT_LIST_HEAD(&info->persistent_gnts); info->persistent_gnts_c = 0; info->connected = BLKIF_STATE_DISCONNECTED; INIT_WORK(&info->work, blkif_restart_queue);