From: Nuno Sa <nuno.sa@analog.com>
Device links will drop their supplier + consumer refcounts
asynchronously. That means that the refcount of the of_node attached to
these devices will also be dropped asynchronously and so we cannot
guarantee the DT overlay assumption that the of_node refcount must be 1 in
__of_changeset_entry_destroy().
Given the above, call the new fwnode_links_flush_queue() helper to flush
the devlink workqueue so we can be sure that all links are dropped before
doing the proper checks.
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
---
drivers/of/dynamic.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
index 3bf27052832f..b7153c72c9c9 100644
--- a/drivers/of/dynamic.c
+++ b/drivers/of/dynamic.c
@@ -14,6 +14,7 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/proc_fs.h>
+#include <linux/fwnode.h>
#include "of_private.h"
@@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
{
+ /*
+ * device links drop their device references (and hence their of_node
+ * references) asynchronously on a dedicated workqueue. Hence we need
+ * to flush it to make sure everything is done before doing the below
+ * checks.
+ */
+ fwnode_links_flush_queue();
if (ce->action == OF_RECONFIG_ATTACH_NODE &&
of_node_check_flag(ce->np, OF_OVERLAY)) {
if (kref_read(&ce->np->kobj.kref) > 1) {
--
2.43.0On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> Device links will drop their supplier + consumer refcounts
> asynchronously. That means that the refcount of the of_node attached to
> these devices will also be dropped asynchronously and so we cannot
> guarantee the DT overlay assumption that the of_node refcount must be 1 in
> __of_changeset_entry_destroy().
>
> Given the above, call the new fwnode_links_flush_queue() helper to flush
> the devlink workqueue so we can be sure that all links are dropped before
> doing the proper checks.
>
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> ---
> drivers/of/dynamic.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> index 3bf27052832f..b7153c72c9c9 100644
> --- a/drivers/of/dynamic.c
> +++ b/drivers/of/dynamic.c
> @@ -14,6 +14,7 @@
> #include <linux/slab.h>
> #include <linux/string.h>
> #include <linux/proc_fs.h>
> +#include <linux/fwnode.h>
>
> #include "of_private.h"
>
> @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
>
> static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
> {
> + /*
> + * device links drop their device references (and hence their of_node
> + * references) asynchronously on a dedicated workqueue. Hence we need
> + * to flush it to make sure everything is done before doing the below
> + * checks.
> + */
> + fwnode_links_flush_queue();
> if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> of_node_check_flag(ce->np, OF_OVERLAY)) {
> if (kref_read(&ce->np->kobj.kref) > 1) {
>
Hi Rob and Frank,
Any way you could take a look at this and see if you're ok with the change in the
overlay code?
On the devlink side , we already got the ok from Rafael.
Thanks!
- Nuno Sá
On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno Sá wrote:
> On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> > Device links will drop their supplier + consumer refcounts
> > asynchronously. That means that the refcount of the of_node attached to
> > these devices will also be dropped asynchronously and so we cannot
> > guarantee the DT overlay assumption that the of_node refcount must be 1 in
> > __of_changeset_entry_destroy().
> >
> > Given the above, call the new fwnode_links_flush_queue() helper to flush
> > the devlink workqueue so we can be sure that all links are dropped before
> > doing the proper checks.
> >
> > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > ---
> > drivers/of/dynamic.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> > index 3bf27052832f..b7153c72c9c9 100644
> > --- a/drivers/of/dynamic.c
> > +++ b/drivers/of/dynamic.c
> > @@ -14,6 +14,7 @@
> > #include <linux/slab.h>
> > #include <linux/string.h>
> > #include <linux/proc_fs.h>
> > +#include <linux/fwnode.h>
> >
> > #include "of_private.h"
> >
> > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
> >
> > static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
> > {
> > + /*
> > + * device links drop their device references (and hence their of_node
> > + * references) asynchronously on a dedicated workqueue. Hence we need
> > + * to flush it to make sure everything is done before doing the below
> > + * checks.
> > + */
> > + fwnode_links_flush_queue();
> > if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> > of_node_check_flag(ce->np, OF_OVERLAY)) {
> > if (kref_read(&ce->np->kobj.kref) > 1) {
> >
>
> Hi Rob and Frank,
>
> Any way you could take a look at this and see if you're ok with the change in the
> overlay code?
>
> On the devlink side , we already got the ok from Rafael.
Didn't Saravana say he was going to look at this? As of yesterday, he's
also a DT maintainer so deferring to him.
Rob
On Tue, 2024-02-13 at 08:51 -0600, Rob Herring wrote:
> On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno Sá wrote:
> > On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> > > Device links will drop their supplier + consumer refcounts
> > > asynchronously. That means that the refcount of the of_node attached to
> > > these devices will also be dropped asynchronously and so we cannot
> > > guarantee the DT overlay assumption that the of_node refcount must be 1 in
> > > __of_changeset_entry_destroy().
> > >
> > > Given the above, call the new fwnode_links_flush_queue() helper to flush
> > > the devlink workqueue so we can be sure that all links are dropped before
> > > doing the proper checks.
> > >
> > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > ---
> > > drivers/of/dynamic.c | 8 ++++++++
> > > 1 file changed, 8 insertions(+)
> > >
> > > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> > > index 3bf27052832f..b7153c72c9c9 100644
> > > --- a/drivers/of/dynamic.c
> > > +++ b/drivers/of/dynamic.c
> > > @@ -14,6 +14,7 @@
> > > #include <linux/slab.h>
> > > #include <linux/string.h>
> > > #include <linux/proc_fs.h>
> > > +#include <linux/fwnode.h>
> > >
> > > #include "of_private.h"
> > >
> > > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
> > >
> > > static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
> > > {
> > > + /*
> > > + * device links drop their device references (and hence their
> > > of_node
> > > + * references) asynchronously on a dedicated workqueue. Hence we
> > > need
> > > + * to flush it to make sure everything is done before doing the
> > > below
> > > + * checks.
> > > + */
> > > + fwnode_links_flush_queue();
> > > if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> > > of_node_check_flag(ce->np, OF_OVERLAY)) {
> > > if (kref_read(&ce->np->kobj.kref) > 1) {
> > >
> >
> > Hi Rob and Frank,
> >
> > Any way you could take a look at this and see if you're ok with the change
> > in the
> > overlay code?
> >
> > On the devlink side , we already got the ok from Rafael.
>
> Didn't Saravana say he was going to look at this? As of yesterday, he's
> also a DT maintainer so deferring to him.
>
Yeah, I did asked him but I guess he never had the time for it... Saravana,
could you please give some feedback on this? I think the most sensible part is
on the devlink side but I assume this is not going to be merged without an ack
from a DT maintainer...
- Nuno Sá
On Tue, Feb 13, 2024 at 6:57 AM Nuno Sá <noname.nuno@gmail.com> wrote:
>
> On Tue, 2024-02-13 at 08:51 -0600, Rob Herring wrote:
> > On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno Sá wrote:
> > > On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> > > > Device links will drop their supplier + consumer refcounts
> > > > asynchronously. That means that the refcount of the of_node attached to
> > > > these devices will also be dropped asynchronously and so we cannot
> > > > guarantee the DT overlay assumption that the of_node refcount must be 1 in
> > > > __of_changeset_entry_destroy().
> > > >
> > > > Given the above, call the new fwnode_links_flush_queue() helper to flush
> > > > the devlink workqueue so we can be sure that all links are dropped before
> > > > doing the proper checks.
> > > >
> > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > ---
> > > > drivers/of/dynamic.c | 8 ++++++++
> > > > 1 file changed, 8 insertions(+)
> > > >
> > > > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> > > > index 3bf27052832f..b7153c72c9c9 100644
> > > > --- a/drivers/of/dynamic.c
> > > > +++ b/drivers/of/dynamic.c
> > > > @@ -14,6 +14,7 @@
> > > > #include <linux/slab.h>
> > > > #include <linux/string.h>
> > > > #include <linux/proc_fs.h>
> > > > +#include <linux/fwnode.h>
> > > >
> > > > #include "of_private.h"
> > > >
> > > > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
> > > >
> > > > static void __of_changeset_entry_destroy(struct of_changeset_entry *ce)
> > > > {
> > > > + /*
> > > > + * device links drop their device references (and hence their
> > > > of_node
> > > > + * references) asynchronously on a dedicated workqueue. Hence we
> > > > need
> > > > + * to flush it to make sure everything is done before doing the
> > > > below
> > > > + * checks.
> > > > + */
> > > > + fwnode_links_flush_queue();
> > > > if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> > > > of_node_check_flag(ce->np, OF_OVERLAY)) {
> > > > if (kref_read(&ce->np->kobj.kref) > 1) {
> > > >
> > >
> > > Hi Rob and Frank,
> > >
> > > Any way you could take a look at this and see if you're ok with the change
> > > in the
> > > overlay code?
> > >
> > > On the devlink side , we already got the ok from Rafael.
> >
> > Didn't Saravana say he was going to look at this? As of yesterday, he's
> > also a DT maintainer so deferring to him.
> >
>
> Yeah, I did asked him but I guess he never had the time for it... Saravana,
> could you please give some feedback on this? I think the most sensible part is
> on the devlink side but I assume this is not going to be merged without an ack
> from a DT maintainer...
Sorry for the delay Nuno. I'll get to this. I promise. This week is a bit busy.
-Saravana
On Tue, 2024-02-13 at 19:44 -0800, Saravana Kannan wrote:
> On Tue, Feb 13, 2024 at 6:57 AM Nuno Sá <noname.nuno@gmail.com> wrote:
> >
> > On Tue, 2024-02-13 at 08:51 -0600, Rob Herring wrote:
> > > On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno Sá wrote:
> > > > On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> > > > > Device links will drop their supplier + consumer refcounts
> > > > > asynchronously. That means that the refcount of the of_node attached
> > > > > to
> > > > > these devices will also be dropped asynchronously and so we cannot
> > > > > guarantee the DT overlay assumption that the of_node refcount must be
> > > > > 1 in
> > > > > __of_changeset_entry_destroy().
> > > > >
> > > > > Given the above, call the new fwnode_links_flush_queue() helper to
> > > > > flush
> > > > > the devlink workqueue so we can be sure that all links are dropped
> > > > > before
> > > > > doing the proper checks.
> > > > >
> > > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > > ---
> > > > > drivers/of/dynamic.c | 8 ++++++++
> > > > > 1 file changed, 8 insertions(+)
> > > > >
> > > > > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> > > > > index 3bf27052832f..b7153c72c9c9 100644
> > > > > --- a/drivers/of/dynamic.c
> > > > > +++ b/drivers/of/dynamic.c
> > > > > @@ -14,6 +14,7 @@
> > > > > #include <linux/slab.h>
> > > > > #include <linux/string.h>
> > > > > #include <linux/proc_fs.h>
> > > > > +#include <linux/fwnode.h>
> > > > >
> > > > > #include "of_private.h"
> > > > >
> > > > > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
> > > > >
> > > > > static void __of_changeset_entry_destroy(struct of_changeset_entry
> > > > > *ce)
> > > > > {
> > > > > + /*
> > > > > + * device links drop their device references (and hence their
> > > > > of_node
> > > > > + * references) asynchronously on a dedicated workqueue. Hence we
> > > > > need
> > > > > + * to flush it to make sure everything is done before doing the
> > > > > below
> > > > > + * checks.
> > > > > + */
> > > > > + fwnode_links_flush_queue();
> > > > > if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> > > > > of_node_check_flag(ce->np, OF_OVERLAY)) {
> > > > > if (kref_read(&ce->np->kobj.kref) > 1) {
> > > > >
> > > >
> > > > Hi Rob and Frank,
> > > >
> > > > Any way you could take a look at this and see if you're ok with the
> > > > change
> > > > in the
> > > > overlay code?
> > > >
> > > > On the devlink side , we already got the ok from Rafael.
> > >
> > > Didn't Saravana say he was going to look at this? As of yesterday, he's
> > > also a DT maintainer so deferring to him.
> > >
> >
> > Yeah, I did asked him but I guess he never had the time for it... Saravana,
> > could you please give some feedback on this? I think the most sensible part
> > is
> > on the devlink side but I assume this is not going to be merged without an
> > ack
> > from a DT maintainer...
>
> Sorry for the delay Nuno. I'll get to this. I promise. This week is a bit
> busy.
>
No worries. Just making sure it's not forgotten :)
- Nuno Sá
On Wed, Feb 14, 2024 at 4:48 AM Nuno Sá <noname.nuno@gmail.com> wrote:
>
> On Tue, 2024-02-13 at 19:44 -0800, Saravana Kannan wrote:
> > On Tue, Feb 13, 2024 at 6:57 AM Nuno Sá <noname.nuno@gmail.com> wrote:
> > >
> > > On Tue, 2024-02-13 at 08:51 -0600, Rob Herring wrote:
> > > > On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno Sá wrote:
> > > > > On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> > > > > > Device links will drop their supplier + consumer refcounts
> > > > > > asynchronously. That means that the refcount of the of_node attached
> > > > > > to
> > > > > > these devices will also be dropped asynchronously and so we cannot
> > > > > > guarantee the DT overlay assumption that the of_node refcount must be
> > > > > > 1 in
> > > > > > __of_changeset_entry_destroy().
> > > > > >
> > > > > > Given the above, call the new fwnode_links_flush_queue() helper to
> > > > > > flush
> > > > > > the devlink workqueue so we can be sure that all links are dropped
> > > > > > before
> > > > > > doing the proper checks.
> > > > > >
> > > > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > > > ---
> > > > > > drivers/of/dynamic.c | 8 ++++++++
> > > > > > 1 file changed, 8 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> > > > > > index 3bf27052832f..b7153c72c9c9 100644
> > > > > > --- a/drivers/of/dynamic.c
> > > > > > +++ b/drivers/of/dynamic.c
> > > > > > @@ -14,6 +14,7 @@
> > > > > > #include <linux/slab.h>
> > > > > > #include <linux/string.h>
> > > > > > #include <linux/proc_fs.h>
> > > > > > +#include <linux/fwnode.h>
> > > > > >
> > > > > > #include "of_private.h"
> > > > > >
> > > > > > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
> > > > > >
> > > > > > static void __of_changeset_entry_destroy(struct of_changeset_entry
> > > > > > *ce)
> > > > > > {
> > > > > > + /*
> > > > > > + * device links drop their device references (and hence their
> > > > > > of_node
> > > > > > + * references) asynchronously on a dedicated workqueue. Hence we
> > > > > > need
> > > > > > + * to flush it to make sure everything is done before doing the
> > > > > > below
> > > > > > + * checks.
> > > > > > + */
> > > > > > + fwnode_links_flush_queue();
> > > > > > if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> > > > > > of_node_check_flag(ce->np, OF_OVERLAY)) {
> > > > > > if (kref_read(&ce->np->kobj.kref) > 1) {
> > > > > >
> > > > >
> > > > > Hi Rob and Frank,
> > > > >
> > > > > Any way you could take a look at this and see if you're ok with the
> > > > > change
> > > > > in the
> > > > > overlay code?
> > > > >
> > > > > On the devlink side , we already got the ok from Rafael.
> > > >
> > > > Didn't Saravana say he was going to look at this? As of yesterday, he's
> > > > also a DT maintainer so deferring to him.
> > > >
> > >
> > > Yeah, I did asked him but I guess he never had the time for it... Saravana,
> > > could you please give some feedback on this? I think the most sensible part
> > > is
> > > on the devlink side but I assume this is not going to be merged without an
> > > ack
> > > from a DT maintainer...
> >
> > Sorry for the delay Nuno. I'll get to this. I promise. This week is a bit
> > busy.
> >
>
> No worries. Just making sure it's not forgotten :)
Hi Nuno,
Thanks for nudging me about this issue.
I replied to a similar patch series that Herve sent out last year.
Chose to reply to that because it had fewer issues to fix and Herve
sent it out a while ago.
https://lore.kernel.org/all/20231130174126.688486-1-herve.codina@bootlin.com/
Can you please chime in there?
Thanks,
Saravana
On Tue, 2024-02-20 at 16:39 -0800, Saravana Kannan wrote:
> On Wed, Feb 14, 2024 at 4:48 AM Nuno Sá <noname.nuno@gmail.com> wrote:
> >
> > On Tue, 2024-02-13 at 19:44 -0800, Saravana Kannan wrote:
> > > On Tue, Feb 13, 2024 at 6:57 AM Nuno Sá <noname.nuno@gmail.com> wrote:
> > > >
> > > > On Tue, 2024-02-13 at 08:51 -0600, Rob Herring wrote:
> > > > > On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno Sá wrote:
> > > > > > On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> > > > > > > Device links will drop their supplier + consumer refcounts
> > > > > > > asynchronously. That means that the refcount of the of_node attached
> > > > > > > to
> > > > > > > these devices will also be dropped asynchronously and so we cannot
> > > > > > > guarantee the DT overlay assumption that the of_node refcount must be
> > > > > > > 1 in
> > > > > > > __of_changeset_entry_destroy().
> > > > > > >
> > > > > > > Given the above, call the new fwnode_links_flush_queue() helper to
> > > > > > > flush
> > > > > > > the devlink workqueue so we can be sure that all links are dropped
> > > > > > > before
> > > > > > > doing the proper checks.
> > > > > > >
> > > > > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > > > > ---
> > > > > > > drivers/of/dynamic.c | 8 ++++++++
> > > > > > > 1 file changed, 8 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> > > > > > > index 3bf27052832f..b7153c72c9c9 100644
> > > > > > > --- a/drivers/of/dynamic.c
> > > > > > > +++ b/drivers/of/dynamic.c
> > > > > > > @@ -14,6 +14,7 @@
> > > > > > > #include <linux/slab.h>
> > > > > > > #include <linux/string.h>
> > > > > > > #include <linux/proc_fs.h>
> > > > > > > +#include <linux/fwnode.h>
> > > > > > >
> > > > > > > #include "of_private.h"
> > > > > > >
> > > > > > > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
> > > > > > >
> > > > > > > static void __of_changeset_entry_destroy(struct of_changeset_entry
> > > > > > > *ce)
> > > > > > > {
> > > > > > > + /*
> > > > > > > + * device links drop their device references (and hence their
> > > > > > > of_node
> > > > > > > + * references) asynchronously on a dedicated workqueue. Hence we
> > > > > > > need
> > > > > > > + * to flush it to make sure everything is done before doing the
> > > > > > > below
> > > > > > > + * checks.
> > > > > > > + */
> > > > > > > + fwnode_links_flush_queue();
> > > > > > > if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> > > > > > > of_node_check_flag(ce->np, OF_OVERLAY)) {
> > > > > > > if (kref_read(&ce->np->kobj.kref) > 1) {
> > > > > > >
> > > > > >
> > > > > > Hi Rob and Frank,
> > > > > >
> > > > > > Any way you could take a look at this and see if you're ok with the
> > > > > > change
> > > > > > in the
> > > > > > overlay code?
> > > > > >
> > > > > > On the devlink side , we already got the ok from Rafael.
> > > > >
> > > > > Didn't Saravana say he was going to look at this? As of yesterday, he's
> > > > > also a DT maintainer so deferring to him.
> > > > >
> > > >
> > > > Yeah, I did asked him but I guess he never had the time for it... Saravana,
> > > > could you please give some feedback on this? I think the most sensible part
> > > > is
> > > > on the devlink side but I assume this is not going to be merged without an
> > > > ack
> > > > from a DT maintainer...
> > >
> > > Sorry for the delay Nuno. I'll get to this. I promise. This week is a bit
> > > busy.
> > >
> >
> > No worries. Just making sure it's not forgotten :)
>
> Hi Nuno,
>
> Thanks for nudging me about this issue.
>
> I replied to a similar patch series that Herve sent out last year.
> Chose to reply to that because it had fewer issues to fix and Herve
> sent it out a while ago.
Ehehe, FWIW, I did sent it out before I believe:
https://lore.kernel.org/lkml/20231127-fix-device-links-overlays-v1-1-d7438f56d025@analog.com/
I just got no attention and it took some time until I got some feedback (I also
pushed for it with resends). If you follow the links in the cover, you'll see I first
started (and spotted the issue) the effort in May last year.
That said, I'm more than fine with whatever series is taken. I just care about the
problem being solved :)
- Nuno Sá
On Tue, 2024-02-20 at 16:39 -0800, Saravana Kannan wrote:
> On Wed, Feb 14, 2024 at 4:48 AM Nuno Sá <noname.nuno@gmail.com> wrote:
> >
> > On Tue, 2024-02-13 at 19:44 -0800, Saravana Kannan wrote:
> > > On Tue, Feb 13, 2024 at 6:57 AM Nuno Sá <noname.nuno@gmail.com> wrote:
> > > >
> > > > On Tue, 2024-02-13 at 08:51 -0600, Rob Herring wrote:
> > > > > On Mon, Feb 12, 2024 at 01:10:27PM +0100, Nuno Sá wrote:
> > > > > > On Mon, 2024-02-05 at 13:09 +0100, Nuno Sa wrote:
> > > > > > > Device links will drop their supplier + consumer refcounts
> > > > > > > asynchronously. That means that the refcount of the of_node attached
> > > > > > > to
> > > > > > > these devices will also be dropped asynchronously and so we cannot
> > > > > > > guarantee the DT overlay assumption that the of_node refcount must be
> > > > > > > 1 in
> > > > > > > __of_changeset_entry_destroy().
> > > > > > >
> > > > > > > Given the above, call the new fwnode_links_flush_queue() helper to
> > > > > > > flush
> > > > > > > the devlink workqueue so we can be sure that all links are dropped
> > > > > > > before
> > > > > > > doing the proper checks.
> > > > > > >
> > > > > > > Signed-off-by: Nuno Sa <nuno.sa@analog.com>
> > > > > > > ---
> > > > > > > drivers/of/dynamic.c | 8 ++++++++
> > > > > > > 1 file changed, 8 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c
> > > > > > > index 3bf27052832f..b7153c72c9c9 100644
> > > > > > > --- a/drivers/of/dynamic.c
> > > > > > > +++ b/drivers/of/dynamic.c
> > > > > > > @@ -14,6 +14,7 @@
> > > > > > > #include <linux/slab.h>
> > > > > > > #include <linux/string.h>
> > > > > > > #include <linux/proc_fs.h>
> > > > > > > +#include <linux/fwnode.h>
> > > > > > >
> > > > > > > #include "of_private.h"
> > > > > > >
> > > > > > > @@ -518,6 +519,13 @@ EXPORT_SYMBOL(of_changeset_create_node);
> > > > > > >
> > > > > > > static void __of_changeset_entry_destroy(struct of_changeset_entry
> > > > > > > *ce)
> > > > > > > {
> > > > > > > + /*
> > > > > > > + * device links drop their device references (and hence their
> > > > > > > of_node
> > > > > > > + * references) asynchronously on a dedicated workqueue. Hence we
> > > > > > > need
> > > > > > > + * to flush it to make sure everything is done before doing the
> > > > > > > below
> > > > > > > + * checks.
> > > > > > > + */
> > > > > > > + fwnode_links_flush_queue();
> > > > > > > if (ce->action == OF_RECONFIG_ATTACH_NODE &&
> > > > > > > of_node_check_flag(ce->np, OF_OVERLAY)) {
> > > > > > > if (kref_read(&ce->np->kobj.kref) > 1) {
> > > > > > >
> > > > > >
> > > > > > Hi Rob and Frank,
> > > > > >
> > > > > > Any way you could take a look at this and see if you're ok with the
> > > > > > change
> > > > > > in the
> > > > > > overlay code?
> > > > > >
> > > > > > On the devlink side , we already got the ok from Rafael.
> > > > >
> > > > > Didn't Saravana say he was going to look at this? As of yesterday, he's
> > > > > also a DT maintainer so deferring to him.
> > > > >
> > > >
> > > > Yeah, I did asked him but I guess he never had the time for it... Saravana,
> > > > could you please give some feedback on this? I think the most sensible part
> > > > is
> > > > on the devlink side but I assume this is not going to be merged without an
> > > > ack
> > > > from a DT maintainer...
> > >
> > > Sorry for the delay Nuno. I'll get to this. I promise. This week is a bit
> > > busy.
> > >
> >
> > No worries. Just making sure it's not forgotten :)
>
> Hi Nuno,
>
> Thanks for nudging me about this issue.
>
Hi Saravana,
> I replied to a similar patch series that Herve sent out last year.
> Chose to reply to that because it had fewer issues to fix and Herve
> sent it out a while ago.
I think it's fixing the same issues but as he sent first, fair enough :)
> https://lore.kernel.org/all/20231130174126.688486-1-herve.codina@bootlin.com/
>
> Can you please chime in there?
>
Already did... Please look at my first patch. It already has an ack from Rafael and I
think it's fairly close with what you want (it might need some naming improvements
though).
- Nuno Sá
On Mon, Feb 05, 2024 at 01:09:33PM +0100, Nuno Sa via B4 Relay wrote: > From: Nuno Sa <nuno.sa@analog.com> > > Device links will drop their supplier + consumer refcounts > asynchronously. That means that the refcount of the of_node attached to > these devices will also be dropped asynchronously and so we cannot > guarantee the DT overlay assumption that the of_node refcount must be 1 in > __of_changeset_entry_destroy(). > > Given the above, call the new fwnode_links_flush_queue() helper to flush > the devlink workqueue so we can be sure that all links are dropped before > doing the proper checks. Have you seen my comments against v1? > +++ b/drivers/of/dynamic.c > @@ -14,6 +14,7 @@ > #include <linux/slab.h> > #include <linux/string.h> > #include <linux/proc_fs.h> > +#include <linux/fwnode.h> Try to squeeze this to make it ordered (with given context it may go before linux/s* ones, but maybe you may find a better spot). ... > + /* > + * device links drop their device references (and hence their of_node Device links... > + * references) asynchronously on a dedicated workqueue. Hence we need > + * to flush it to make sure everything is done before doing the below > + * checks. > + */ -- With Best Regards, Andy Shevchenko
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