[PATCH v2 03/10] liveupdate: Allow file handlers to mark retrieve failures as retryable

[sashiko-bot at kernel.org]

> From: Pasha Tatashin <pasha.tatashin at soleen.com>
> 
> When luo_retrieve_file() invokes a handler's .retrieve() callback and it
> returns an error, LUO currently records the error in
> luo_file->retrieve_status and blocks any subsequent retrieve attempts.
> This is necessary when the handler has already partially consumed or
> freed the preserved KHO state.
> 
> However, with user arguments passed to .retrieve(), a handler may fail
> early while validating caller-supplied parameters (such as a missing
> argument, an invalid or read-only target file descriptor, or a non-empty
> target file) before touching any preserved KHO state. In such cases,
> userspace should be able to fix the argument and retry
> LIVEUPDATE_SESSION_RETRIEVE_FD, and if the file is never retrieved,
> .finish() must still run to release the preserved KHO state.
> 
> Add a retryable output flag to struct liveupdate_file_op_args. When a
> handler sets args->retryable = true on error, luo_retrieve_file() leaves
> luo_file->retrieve_status at 0 so the retrieve operation can be retried
> and .finish() will still clean up the unconsumed preserved state if the
> session is finished without retrieving the file.
> 
> Signed-off-by: Pasha Tatashin <pasha.tatashin at soleen.com>
> Signed-off-by: David Matlack <dmatlack at google.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261022225035.377445-1-dmatlack@google.com?part=3