[PATCH v2 0/1] liveupdate: Add documentation for file dependencies

[PATCH v2 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.

Changelog:

v2:
 - Rebased on liveupdate next branch.
 - Fixed documentation.

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

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


base-commit: 945d61765894dda2f0344de50cb1ade2e51b66fd
-- 
2.55.0.1032.g73a4cd73de-goog

[PATCH v2 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..a39992da504f 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's
+ * .freeze() callback, but some of these might need resolution during file
+ * handler's .preserve() callback based on 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
-- 
2.55.0.1032.g73a4cd73de-goog

Re: [PATCH v2 1/1] liveupdate: luo_file: Add documentation for dependencies

[sashiko-bot]

> 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>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260910173659.1945246-2-skhawaja@google.com?part=1