[PATCH 0/1] liveupdate: Add documentation for file dependencies

[PATCH 0/1] liveupdate: Add documentation for file dependencies

[Samiullah Khawaja]

I sent out v3 of liveupdate_get_file_incoming() and
liveupdate_get_token_outgoing() series to add documentation for
dependencies.

https://lore.kernel.org/all/20260820191854.1642931-1-skhawaja@google.com/

But since v2 of that series is already merged into kho/next, I am
sending the documentation as a separate patch.

Samiullah Khawaja (1):
  liveupdate: luo_file: Add documentation for dependencies

 kernel/liveupdate/luo_file.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)


base-commit: c65687600ed075d237a204755d99ad538db34b47
-- 
2.55.0.1003.g10538fe699-goog

[PATCH 1/1] liveupdate: luo_file: Add documentation for dependencies

[Samiullah Khawaja]

Add documentation for dependencies between FDs preserved by File
Handlers. This supplements the previously added
liveupdate_get_token_outgoing() and liveupdate_get_file_incoming()
internal APIs to allow File Handlers to resolve dependencies.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 kernel/liveupdate/luo_file.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
index dbae0715220b..0a4994377c98 100644
--- a/kernel/liveupdate/luo_file.c
+++ b/kernel/liveupdate/luo_file.c
@@ -91,6 +91,21 @@
  *    again later. If the issue cannot be resolved, these resources will be held
  *    by LUO until the next live update cycle, at which point they will be
  *    discarded.
+ *
+ * Dependencies:
+ *
+ * Preserved files may have dependencies on other files that also need to be
+ * preserved during a live update. A file handler can resolve these dependencies
+ * by querying the token of the dependency. That token can then be serialized
+ * and used to fetch the dependency during the retrieve() callback in the next
+ * kernel.
+ *
+ * Some of these dependencies can be resolved late during File Handler freeze()
+ * callback, but some of these might need resolution during File Handler
+ * preserve() callback based on the constraints such as immutability and
+ * performance. This introduces an order of preservation. Note that the order of
+ * preservation of dependencies can be safely relaxed later, but it cannot be
+ * enforced later.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-- 
2.55.0.1003.g10538fe699-goog

Re: [PATCH 1/1] liveupdate: luo_file: Add documentation for dependencies

[Mike Rapoport]

Hi Sami,

> Add documentation for dependencies between FDs preserved by File
> Handlers. This supplements the previously added

Why capital F and H? :)

I think we use "file handler" in the most places.

-- 
Sincerely yours,
Mike.

Re: [PATCH 1/1] liveupdate: luo_file: Add documentation for dependencies

[Samiullah Khawaja]

Hi Mike,

On Sun, Sep 06, 2026 at 11:39:41PM +0300, Mike Rapoport wrote:
>Hi Sami,
>
>> Add documentation for dependencies between FDs preserved by File
>> Handlers. This supplements the previously added
>
>Why capital F and H? :)
>
>I think we use "file handler" in the most places.

Ah, force of habit! You are right, it should be lowercased.

Let me send a v2 for this patch with the capitalization fixed. I will
check if I did the same in the source file also.

Thanks,
Sami
>
>-- 
>Sincerely yours,
>Mike.
>