Re: [PATCH 1/3] livepatch: Convert error about unsupported reliable stacktrace into a warning
On Wed 2019-04-24 10:55:48, Petr Mladek wrote:
> The commit d0807da78e11d46f ("livepatch: Remove immediate feature") caused
> that any livepatch was refused when reliable stacktraces were not supported
> on the given architecture.
>
> The limitation is too strong. User space processes are safely migrated
> even when entering or leaving the kernel. Kthreads transition would
> need to get forced. But it is safe when:
>
>+ The livepatch does not change the semantic of the code.
>+ Callbacks do not depend on a safely finished transition.
>
> Suggested-by: Josh Poimboeuf
> Signed-off-by: Petr Mladek
> ---
> kernel/livepatch/core.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index eb0ee10a1981..14f33ab6c583 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -1003,11 +1003,10 @@ int klp_enable_patch(struct klp_patch *patch)
> return -ENODEV;
>
> if (!klp_have_reliable_stack()) {
> - pr_err("This architecture doesn't have support for the
> livepatch consistency model.\n");
> - return -EOPNOTSUPP;
> + pr_warn("This architecture doesn't have support for the
> livepatch consistency model.\n");
> + pr_warn("The livepatch transition may never complete.\n");
> }
>
> -
> mutex_lock(_mutex);
>
> ret = klp_init_patch_early(patch);
> --
> 2.16.4
I have committed this patch into for-5.2/core branch.
Best Regards,
Petr
PS: I am going to resend 2nd patch separately with more people
interested into kernel/stacktrace.c.
Also I am going to send two separate patches instead of
the 3rd one (complete warning removal, static err_buf).
Re: [PATCH 1/3] livepatch: Convert error about unsupported reliable stacktrace into a warning
On Wed, Apr 24, 2019 at 10:55:48AM +0200, Petr Mladek wrote:
> The commit d0807da78e11d46f ("livepatch: Remove immediate feature") caused
> that any livepatch was refused when reliable stacktraces were not supported
> on the given architecture.
>
> The limitation is too strong. User space processes are safely migrated
> even when entering or leaving the kernel. Kthreads transition would
> need to get forced. But it is safe when:
>
>+ The livepatch does not change the semantic of the code.
>+ Callbacks do not depend on a safely finished transition.
>
> Suggested-by: Josh Poimboeuf
> Signed-off-by: Petr Mladek
Reviewed-by: Kamalesh Babulal
--
Kamalesh
Re: [PATCH 1/3] livepatch: Convert error about unsupported reliable stacktrace into a warning
On Wed, 24 Apr 2019, Petr Mladek wrote:
> The commit d0807da78e11d46f ("livepatch: Remove immediate feature") caused
> that any livepatch was refused when reliable stacktraces were not supported
> on the given architecture.
>
> The limitation is too strong. User space processes are safely migrated
> even when entering or leaving the kernel. Kthreads transition would
> need to get forced. But it is safe when:
>
>+ The livepatch does not change the semantic of the code.
>+ Callbacks do not depend on a safely finished transition.
>
> Suggested-by: Josh Poimboeuf
> Signed-off-by: Petr Mladek
Acked-by: Miroslav Benes
Miroslav
Re: [PATCH 1/3] livepatch: Convert error about unsupported reliable stacktrace into a warning
On Wed, Apr 24, 2019 at 10:55:48AM +0200, Petr Mladek wrote:
> The commit d0807da78e11d46f ("livepatch: Remove immediate feature") caused
> that any livepatch was refused when reliable stacktraces were not supported
> on the given architecture.
>
> The limitation is too strong. User space processes are safely migrated
> even when entering or leaving the kernel. Kthreads transition would
> need to get forced. But it is safe when:
>
>+ The livepatch does not change the semantic of the code.
>+ Callbacks do not depend on a safely finished transition.
>
> Suggested-by: Josh Poimboeuf
> Signed-off-by: Petr Mladek
> ---
> kernel/livepatch/core.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index eb0ee10a1981..14f33ab6c583 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -1003,11 +1003,10 @@ int klp_enable_patch(struct klp_patch *patch)
> return -ENODEV;
>
> if (!klp_have_reliable_stack()) {
> - pr_err("This architecture doesn't have support for the
> livepatch consistency model.\n");
> - return -EOPNOTSUPP;
> + pr_warn("This architecture doesn't have support for the
> livepatch consistency model.\n");
> + pr_warn("The livepatch transition may never complete.\n");
> }
>
> -
> mutex_lock(_mutex);
>
> ret = klp_init_patch_early(patch);
> --
> 2.16.4
>
Acked-by: Josh Poimboeuf
--
Josh
[PATCH 1/3] livepatch: Convert error about unsupported reliable stacktrace into a warning
The commit d0807da78e11d46f ("livepatch: Remove immediate feature") caused
that any livepatch was refused when reliable stacktraces were not supported
on the given architecture.
The limitation is too strong. User space processes are safely migrated
even when entering or leaving the kernel. Kthreads transition would
need to get forced. But it is safe when:
+ The livepatch does not change the semantic of the code.
+ Callbacks do not depend on a safely finished transition.
Suggested-by: Josh Poimboeuf
Signed-off-by: Petr Mladek
---
kernel/livepatch/core.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index eb0ee10a1981..14f33ab6c583 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1003,11 +1003,10 @@ int klp_enable_patch(struct klp_patch *patch)
return -ENODEV;
if (!klp_have_reliable_stack()) {
- pr_err("This architecture doesn't have support for the
livepatch consistency model.\n");
- return -EOPNOTSUPP;
+ pr_warn("This architecture doesn't have support for the
livepatch consistency model.\n");
+ pr_warn("The livepatch transition may never complete.\n");
}
-
mutex_lock(_mutex);
ret = klp_init_patch_early(patch);
--
2.16.4
