Re: [PATCH 09/11] treewide: Convert custom kernel_param_ops .get callbacks to seq_buf via cocci

SeongJae Park <[email protected]> Fri, 22 May 2026 17:45:43 -0700
Newsgroups gmane.linux.kernel.modules,gmane.comp.emulators.kvm.devel,gmane.linux.kernel.mm,gmane.comp.security.apparmor,gmane.linux.kernel.lsm,gmane.linux.uml.devel,gmane.linux.acpi.devel,gmane.linux.kernel.openipmi,gmane.comp.emulators.qemu,gmane.comp.freedesktop.xorg.drivers.intel,gmane.comp.video.dri.devel,gmane.linux.drivers.rdma,gmane.linux.drivers.video-input-infrastructure,gmane.linux.kernel.pci,gmane.linux.scsi,gmane.linux.power-management.general,gmane.linux.ports.ppc64.devel,gmane.linux.serial,gmane.linux.usb.general,gmane.linux.kernel,gmane.linux.kernel.cross-arch,gmane.linux.network,gmane.linux.file-systems
Message-ID <[email protected]> 
+ damon-cunTk1MwBs/[email protected]

On Thu, 21 May 2026 06:33:22 -0700 Kees Cook <[email protected]> wrote:

> Using the following Coccinelle script, convert struct kernel_param_ops
> .get callbacks from "char *" to "struct seq_buf *" when the only write
> to the buffer is via a final call of scnprintf(), snprintf(), sprintf(),
> or sysfs_emit().
> 
> Since seq_buf_printf() will return -1 on overflow, and struct
> kernel_param_ops .get callbacks are expected to truncate without error,
> we must ignore the return value from seq_buf_print() and always return 0
> (as the length is calculated in the common dispatcher code).
> 
> @@
> identifier FN, BUF, KP;
> expression FMT;
> expression list ARGS;
> @@
>  int FN(
> -               char *BUF
> +               struct seq_buf *BUF
>                 , const struct kernel_param *KP)
>  {
>         ... when any
> (
> -       return scnprintf(BUF, PAGE_SIZE, FMT, ARGS);
> |
> -       return snprintf(BUF, PAGE_SIZE, FMT, ARGS);
> |
> -       return sprintf(BUF, FMT, ARGS);
> |
> -       return sysfs_emit(BUF, FMT, ARGS);
> )
> +       seq_buf_printf(BUF, FMT, ARGS);
> +       return 0;
>  }
> 
> No struct kernel_param_ops initializations need changing since
> DEFINE_KERNEL_PARAM_OPS already routes the pointer to .get or .get_str
> via _Generic based on the function signature, so converted callbacks
> are automatically moved from the .get_str to the .get callback.
> 
> Signed-off-by: Kees Cook <[email protected]>
[...]
>  mm/damon/lru_sort.c                           | 14 +++---
>  mm/damon/reclaim.c                            | 14 +++---
>  mm/damon/stat.c                               | 10 ++--

For the above DAMON changes,

Reviewed-by: SeongJae Park <[email protected]>


Thanks,
SJ

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