* [PATCH v2] xen: don't continue xenstore initialization in case of errors
@ 2021-11-15 22:27 Stefano Stabellini
2021-11-16 7:44 ` Jan Beulich
2021-11-17 16:05 ` Boris Ostrovsky
0 siblings, 2 replies; 4+ messages in thread
From: Stefano Stabellini @ 2021-11-15 22:27 UTC (permalink / raw)
To: jgross
Cc: boris.ostrovsky, xen-devel, linux-kernel, sstabellini,
Stefano Stabellini, Stable, jbeulich
From: Stefano Stabellini <stefano.stabellini@xilinx.com>
In case of errors in xenbus_init (e.g. missing xen_store_gfn parameter),
we goto out_error but we forget to reset xen_store_domain_type to
XS_UNKNOWN. As a consequence xenbus_probe_initcall and other initcalls
will still try to initialize xenstore resulting into a crash at boot.
[ 2.479830] Call trace:
[ 2.482314] xb_init_comms+0x18/0x150
[ 2.486354] xs_init+0x34/0x138
[ 2.489786] xenbus_probe+0x4c/0x70
[ 2.498432] xenbus_probe_initcall+0x2c/0x7c
[ 2.503944] do_one_initcall+0x54/0x1b8
[ 2.507358] kernel_init_freeable+0x1ac/0x210
[ 2.511617] kernel_init+0x28/0x130
[ 2.516112] ret_from_fork+0x10/0x20
Cc: <Stable@vger.kernel.org>
Cc: jbeulich@suse.com
Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
---
Changes in v2:
- use return 0 for the success case
- remove err initializer as it is not useful any longer
---
drivers/xen/xenbus/xenbus_probe.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index bd003ca8acbe..5967aa937255 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -909,7 +909,7 @@ static struct notifier_block xenbus_resume_nb = {
static int __init xenbus_init(void)
{
- int err = 0;
+ int err;
uint64_t v = 0;
xen_store_domain_type = XS_UNKNOWN;
@@ -983,8 +983,10 @@ static int __init xenbus_init(void)
*/
proc_create_mount_point("xen");
#endif
+ return 0;
out_error:
+ xen_store_domain_type = XS_UNKNOWN;
return err;
}
--
2.25.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2] xen: don't continue xenstore initialization in case of errors
2021-11-15 22:27 [PATCH v2] xen: don't continue xenstore initialization in case of errors Stefano Stabellini
@ 2021-11-16 7:44 ` Jan Beulich
2021-11-16 20:41 ` Stefano Stabellini
2021-11-17 16:05 ` Boris Ostrovsky
1 sibling, 1 reply; 4+ messages in thread
From: Jan Beulich @ 2021-11-16 7:44 UTC (permalink / raw)
To: Stefano Stabellini
Cc: boris.ostrovsky, xen-devel, linux-kernel, Stefano Stabellini,
Stable, jgross
On 15.11.2021 23:27, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
> In case of errors in xenbus_init (e.g. missing xen_store_gfn parameter),
> we goto out_error but we forget to reset xen_store_domain_type to
> XS_UNKNOWN. As a consequence xenbus_probe_initcall and other initcalls
> will still try to initialize xenstore resulting into a crash at boot.
>
> [ 2.479830] Call trace:
> [ 2.482314] xb_init_comms+0x18/0x150
> [ 2.486354] xs_init+0x34/0x138
> [ 2.489786] xenbus_probe+0x4c/0x70
> [ 2.498432] xenbus_probe_initcall+0x2c/0x7c
> [ 2.503944] do_one_initcall+0x54/0x1b8
> [ 2.507358] kernel_init_freeable+0x1ac/0x210
> [ 2.511617] kernel_init+0x28/0x130
> [ 2.516112] ret_from_fork+0x10/0x20
>
> Cc: <Stable@vger.kernel.org>
> Cc: jbeulich@suse.com
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
For the immediate purpose as described this looks okay, so
Reviewed-by: Jan Beulich <jbeulich@suse.com>
However, aren't there further pieces missing on this error patch:
- clearing of xenstored_ready in case it got set,
- rolling back xenstored_local_init() (XS_LOCAL) and xen_remap()
(XS_HVM).
And shouldn't xs_init() failure when called from xenbus_probe()
also result in the driver not giving the appearance of being usable?
> --- a/drivers/xen/xenbus/xenbus_probe.c
> +++ b/drivers/xen/xenbus/xenbus_probe.c
> @@ -909,7 +909,7 @@ static struct notifier_block xenbus_resume_nb = {
>
> static int __init xenbus_init(void)
> {
> - int err = 0;
> + int err;
> uint64_t v = 0;
> xen_store_domain_type = XS_UNKNOWN;
>
Minor remark: You may want to take the opportunity and add the
missing blank line here to visually separate the assignment from
the declarations.
Jan
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] xen: don't continue xenstore initialization in case of errors
2021-11-16 7:44 ` Jan Beulich
@ 2021-11-16 20:41 ` Stefano Stabellini
0 siblings, 0 replies; 4+ messages in thread
From: Stefano Stabellini @ 2021-11-16 20:41 UTC (permalink / raw)
To: Jan Beulich
Cc: Stefano Stabellini, boris.ostrovsky, xen-devel, linux-kernel,
Stefano Stabellini, Stable, jgross
On Tue, 16 Nov 2021, Jan Beulich wrote:
> On 15.11.2021 23:27, Stefano Stabellini wrote:
> > From: Stefano Stabellini <stefano.stabellini@xilinx.com>
> >
> > In case of errors in xenbus_init (e.g. missing xen_store_gfn parameter),
> > we goto out_error but we forget to reset xen_store_domain_type to
> > XS_UNKNOWN. As a consequence xenbus_probe_initcall and other initcalls
> > will still try to initialize xenstore resulting into a crash at boot.
> >
> > [ 2.479830] Call trace:
> > [ 2.482314] xb_init_comms+0x18/0x150
> > [ 2.486354] xs_init+0x34/0x138
> > [ 2.489786] xenbus_probe+0x4c/0x70
> > [ 2.498432] xenbus_probe_initcall+0x2c/0x7c
> > [ 2.503944] do_one_initcall+0x54/0x1b8
> > [ 2.507358] kernel_init_freeable+0x1ac/0x210
> > [ 2.511617] kernel_init+0x28/0x130
> > [ 2.516112] ret_from_fork+0x10/0x20
> >
> > Cc: <Stable@vger.kernel.org>
> > Cc: jbeulich@suse.com
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
> For the immediate purpose as described this looks okay, so
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
Thank you!
> However, aren't there further pieces missing on this error patch:
> - clearing of xenstored_ready in case it got set,
> - rolling back xenstored_local_init() (XS_LOCAL) and xen_remap()
> (XS_HVM).
> And shouldn't xs_init() failure when called from xenbus_probe()
> also result in the driver not giving the appearance of being usable?
I prioritized this patch because I have a direct test case for this
issue and I can see that this patch solves it. But what you wrote is
true, and I can have a look in the following weeks.
> > --- a/drivers/xen/xenbus/xenbus_probe.c
> > +++ b/drivers/xen/xenbus/xenbus_probe.c
> > @@ -909,7 +909,7 @@ static struct notifier_block xenbus_resume_nb = {
> >
> > static int __init xenbus_init(void)
> > {
> > - int err = 0;
> > + int err;
> > uint64_t v = 0;
> > xen_store_domain_type = XS_UNKNOWN;
> >
>
> Minor remark: You may want to take the opportunity and add the
> missing blank line here to visually separate the assignment from
> the declarations.
>
> Jan
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] xen: don't continue xenstore initialization in case of errors
2021-11-15 22:27 [PATCH v2] xen: don't continue xenstore initialization in case of errors Stefano Stabellini
2021-11-16 7:44 ` Jan Beulich
@ 2021-11-17 16:05 ` Boris Ostrovsky
1 sibling, 0 replies; 4+ messages in thread
From: Boris Ostrovsky @ 2021-11-17 16:05 UTC (permalink / raw)
To: Stefano Stabellini, jgross
Cc: xen-devel, linux-kernel, Stefano Stabellini, Stable, jbeulich
On 11/15/21 5:27 PM, Stefano Stabellini wrote:
> From: Stefano Stabellini <stefano.stabellini@xilinx.com>
>
> In case of errors in xenbus_init (e.g. missing xen_store_gfn parameter),
> we goto out_error but we forget to reset xen_store_domain_type to
> XS_UNKNOWN. As a consequence xenbus_probe_initcall and other initcalls
> will still try to initialize xenstore resulting into a crash at boot.
>
> [ 2.479830] Call trace:
> [ 2.482314] xb_init_comms+0x18/0x150
> [ 2.486354] xs_init+0x34/0x138
> [ 2.489786] xenbus_probe+0x4c/0x70
> [ 2.498432] xenbus_probe_initcall+0x2c/0x7c
> [ 2.503944] do_one_initcall+0x54/0x1b8
> [ 2.507358] kernel_init_freeable+0x1ac/0x210
> [ 2.511617] kernel_init+0x28/0x130
> [ 2.516112] ret_from_fork+0x10/0x20
>
> Cc: <Stable@vger.kernel.org>
> Cc: jbeulich@suse.com
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Applied to for-linus-5.16c
-boris
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-11-17 16:06 UTC | newest]
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2021-11-15 22:27 [PATCH v2] xen: don't continue xenstore initialization in case of errors Stefano Stabellini
2021-11-16 7:44 ` Jan Beulich
2021-11-16 20:41 ` Stefano Stabellini
2021-11-17 16:05 ` Boris Ostrovsky
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