Re: [PATCH v2 02/23] kcsan: Remove redundant zero-initialization of globals

Mark Rutland
2021-11-18T11:11:30Z

On Thu, Nov 18, 2021 at 09:10:06AM +0100, Marco Elver wrote:
> They are implicitly zero-initialized, remove explicit initialization.
> It keeps the upcoming additions to kcsan_ctx consistent with the rest.
>
> No functional change intended.
>
> Signed-off-by: Marco Elver <elver@google.com>
> ---
> init/init_task.c | 9 +--------
> kernel/kcsan/core.c | 5 -----
> 2 files changed, 1 insertion(+), 13 deletions(-)
>
> diff --git a/init/init_task.c b/init/init_task.c
> index 2d024066e27b..61700365ce58 100644
> --- a/init/init_task.c
> +++ b/init/init_task.c
> @@ -181,14 +181,7 @@ struct task_struct init_task
> .kasan_depth = 1,
> #endif
> #ifdef CONFIG_KCSAN
> - .kcsan_ctx = {
> - .disable_count = 0,
> - .atomic_next = 0,
> - .atomic_nest_count = 0,
> - .in_flat_atomic = false,
> - .access_mask = 0,
> - .scoped_accesses = {LIST_POISON1, NULL},
> - },
> + .kcsan_ctx = { .scoped_accesses = {LIST_POISON1, NULL} },

I'd recommend leaving this as:

.kcsan_ctx = {
.scoped_accesses = {LIST_POISON1, NULL},
},

... which'd be consistent with the DEFINE_PER_CPU() usage below, and
makes it easier to add fields to in future without needing structural
changes.

Either way:

Acked-by: Mark Rutland <mark.rutland@arm.com>

> #endif
> #ifdef CONFIG_TRACE_IRQFLAGS
> .softirqs_enabled = 1,
> diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
> index 6bfd3040f46b..e34a1710b7bc 100644
> --- a/kernel/kcsan/core.c
> +++ b/kernel/kcsan/core.c
> @@ -44,11 +44,6 @@ bool kcsan_enabled;
>
> /* Per-CPU kcsan_ctx for interrupts */
> static DEFINE_PER_CPU(struct kcsan_ctx, kcsan_cpu_ctx) = {
> - .disable_count = 0,
> - .atomic_next = 0,
> - .atomic_nest_count = 0,
> - .in_flat_atomic = false,
> - .access_mask = 0,
> .scoped_accesses = {LIST_POISON1, NULL},
> };
>
> --
> 2.34.0.rc2.393.gf8c9666880-goog
>