From: Jani Nikula <jani.nikula@linux•intel.com>
To: Kees Cook <kees@kernel•org>, Luis Chamberlain <mcgrof@kernel•org>
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Subject: Re: [PATCH 10/11] treewide: Manually convert custom kernel_param_ops .get callbacks
Date: Thu, 21 May 2026 20:44:37 +0300 [thread overview]
Message-ID: <5cd0c8dde3687d0aea765f2f21f5e1cd8ba83028@intel.com> (raw)
In-Reply-To: <20260521133326.2465264-10-kees@kernel.org>
On Thu, 21 May 2026, Kees Cook <kees@kernel•org> wrote:
> diff --git a/drivers/gpu/drm/i915/i915_mitigations.c b/drivers/gpu/drm/i915/i915_mitigations.c
> index 6061eae84e9c..99cb38f355b6 100644
> --- a/drivers/gpu/drm/i915/i915_mitigations.c
> +++ b/drivers/gpu/drm/i915/i915_mitigations.c
> @@ -95,33 +95,37 @@ static int mitigations_set(const char *val, const struct kernel_param *kp)
> return 0;
> }
>
> -static int mitigations_get(char *buffer, const struct kernel_param *kp)
> +static int mitigations_get(struct seq_buf *buffer,
> + const struct kernel_param *kp)
> {
> unsigned long local = READ_ONCE(mitigations);
> - int count, i;
> bool enable;
> + int i;
I'm fine with what you have, and I can do these as a follow-up later if
it's too much trouble, but I suggest something like this:
const char *sep = "";
>
> - if (!local)
> - return scnprintf(buffer, PAGE_SIZE, "%s\n", "off");
> + if (!local) {
> + seq_buf_printf(buffer, "%s\n", "off");
> + return 0;
> + }
>
> if (local & BIT(BITS_PER_LONG - 1)) {
> - count = scnprintf(buffer, PAGE_SIZE, "%s,", "auto");
> + seq_buf_printf(buffer, "%s,", "auto");
seq_buf_printf(buffer, "%s%s", sep, "auto");
sep = ",";
(In the printf the sep is just for future expansion, though I don't
expect one.)
> enable = false;
> } else {
> enable = true;
> - count = 0;
> }
>
> for (i = 0; i < ARRAY_SIZE(names); i++) {
> if ((local & BIT(i)) != enable)
> continue;
> -
> - count += scnprintf(buffer + count, PAGE_SIZE - count,
> - "%s%s,", enable ? "" : "!", names[i]);
> + seq_buf_printf(buffer, "%s%s,", enable ? "" : "!", names[i]);
seq_buf_printf(buffer, "%s%s%s", sep, enable ? "" : "!", names[i]);
sep = ",";
> }
seq_buf_puts(buffer, "\n");
>
> - buffer[count - 1] = '\n';
> - return count;
> + /* Replace the trailing comma with a newline. */
> + if (!seq_buf_has_overflowed(buffer) && buffer->len > 0 &&
> + buffer->buffer[buffer->len - 1] == ',')
> + buffer->buffer[buffer->len - 1] = '\n';
Drop the above.
I.e. keep track of sep while printing to avoid removing it later.
BR,
Jani.
> +
> + return 0;
> }
>
> static DEFINE_KERNEL_PARAM_OPS(ops, mitigations_set, mitigations_get);
--
Jani Nikula, Intel
next prev parent reply other threads:[~2026-05-21 17:45 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-21 13:33 [PATCH 00/11] Convert moduleparams to seq_buf Kees Cook
2026-05-21 13:33 ` [PATCH 01/11] params: bound array element output to the caller's page buffer Kees Cook
2026-05-21 16:46 ` David Laight
2026-06-01 20:23 ` Matthew Wilcox
2026-06-02 11:26 ` Andy Shevchenko
2026-06-02 12:33 ` Jason Gunthorpe
2026-06-02 13:04 ` David Laight
2026-05-21 13:33 ` [PATCH 02/11] panic: Replace panic_print_get() with generic helper Kees Cook
2026-05-21 13:33 ` [PATCH 03/11] moduleparam: Add DEFINE_KERNEL_PARAM_OPS macro family Kees Cook
2026-05-25 13:27 ` Petr Pavlu
2026-05-21 13:33 ` [PATCH 04/11] treewide: Convert struct kernel_param_ops initializers to DEFINE_KERNEL_PARAM_OPS Kees Cook
2026-05-21 13:59 ` Sean Christopherson
2026-05-22 17:01 ` Rafael J. Wysocki
2026-05-23 0:38 ` SeongJae Park
2026-05-25 13:35 ` Petr Pavlu
2026-05-21 13:33 ` [PATCH 05/11] moduleparam: Rename .get field to .get_str Kees Cook
2026-05-21 13:33 ` [PATCH 06/11] moduleparam: Add seq_buf-based .get callback alongside .get_str Kees Cook
2026-05-25 16:19 ` Petr Pavlu
2026-05-21 13:33 ` [PATCH 07/11] moduleparam: Route DEFINE_KERNEL_PARAM_OPS get pointer via _Generic Kees Cook
2026-05-25 16:24 ` Petr Pavlu
2026-05-21 13:33 ` [PATCH 08/11] params: Convert generic kernel_param_ops .get helpers to seq_buf Kees Cook
2026-05-25 17:10 ` Petr Pavlu
2026-05-21 13:33 ` [PATCH 09/11] treewide: Convert custom kernel_param_ops .get callbacks to seq_buf via cocci Kees Cook
2026-05-21 13:45 ` Sean Christopherson
2026-05-22 17:03 ` Rafael J. Wysocki
2026-05-23 0:45 ` SeongJae Park
2026-05-21 13:33 ` [PATCH 10/11] treewide: Manually convert custom kernel_param_ops .get callbacks Kees Cook
2026-05-21 17:44 ` Jani Nikula [this message]
2026-05-22 17:05 ` Rafael J. Wysocki
2026-05-21 13:33 ` [PATCH 11/11] moduleparam: Drop legacy kernel_param_ops .get_str field and dispatch logic Kees Cook
2026-05-26 6:53 ` [PATCH 00/11] Convert moduleparams to seq_buf Petr Pavlu
2026-06-01 19:59 ` Kees Cook
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