Re: [PATCH V2 1/3] pstore: Alert on backend write error

Ard Biesheuvel
2022-10-14T14:47:15Z

On Thu, 13 Oct 2022 at 23:11, Guilherme G. Piccoli <gpiccoli@igalia.com> wrote:
>
> The pstore dump function doesn't alert at all on errors - despite
> pstore is usually a last resource and if it fails users won't be
> able to read the kernel log, this is not the case for server users
> with serial access, for example.
>
> So, let's at least attempt to inform such advanced users on the first
> backend writing error detected during the kmsg dump - this is also
> very useful for pstore debugging purposes.
>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>
>
> V2:
> - Show error message late, outside of the critical region
> (thanks Kees for the idea!).
>
>
> fs/pstore/platform.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 06c2c66af332..cbc0b468c1ab 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -393,6 +393,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
> const char *why;
> unsigned int part = 1;
> unsigned long flags = 0;
> + int saved_ret = 0;
> int ret;
>
> why = kmsg_dump_reason_str(reason);
> @@ -463,12 +464,21 @@ static void pstore_dump(struct kmsg_dumper *dumper,
> if (ret == 0 && reason == KMSG_DUMP_OOPS) {
> pstore_new_entry = 1;
> pstore_timer_kick();
> + } else {
> + /* Preserve only the first non-zero returned value. */
> + if (!saved_ret)
> + saved_ret = ret;
> }
>
> total += record.size;
> part++;
> }
> spin_unlock_irqrestore(&psinfo->buf_lock, flags);
> +
> + if (saved_ret) {
> + pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
> + saved_ret);
> + }
> }
>
> static struct kmsg_dumper pstore_dumper = {
> --
> 2.38.0
>