[PATCH] clocksource: riscv: Patch riscv_clock_next_event() jump before first use

[Conor Dooley]

Hey Matt,

On Wed, Feb 01, 2023 at 06:41:52PM +0000, Matt Evans wrote:
> A static key is used to select between SBI and Sstc timer usage in
> riscv_clock_next_event(), but currently the direction is resolved
> after cpuhp_setup_state() is called (which sets the next event).  The
> first event will therefore fall through the sbi_set_timer() path; this
> breaks Sstc-only systems.  So, apply the jump patching before first
> use.
> 
> Signed-off-by: Matt Evans <mev at rivosinc.com>

Your logic in this patch looks grand, just got two process bits for ya.
Firstly, you're missing a fixes tag, which I would imagine is:
Fixes: 9f7a8ff6391f ("RISC-V: Prefer sstc extension if available")

Also, of late, the clocksource maintainers, who you have not CCed,
have been the ones that pick up patches that only touch this driver.
Might be worth a resubmission CCing them...

Cheers,
Conor.

> ---
>  drivers/clocksource/timer-riscv.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> index 969a552da8d2..a36d173fd6cd 100644
> --- a/drivers/clocksource/timer-riscv.c
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -177,6 +177,11 @@ static int __init riscv_timer_init_dt(struct device_node *n)
>  		return error;
>  	}
>  
> +	if (riscv_isa_extension_available(NULL, SSTC)) {
> +		pr_info("Timer interrupt in S-mode is available via sstc extension\n");
> +		static_branch_enable(&riscv_sstc_available);
> +	}
> +
>  	error = cpuhp_setup_state(CPUHP_AP_RISCV_TIMER_STARTING,
>  			 "clockevents/riscv/timer:starting",
>  			 riscv_timer_starting_cpu, riscv_timer_dying_cpu);
> @@ -184,11 +189,6 @@ static int __init riscv_timer_init_dt(struct device_node *n)
>  		pr_err("cpu hp setup state failed for RISCV timer [%d]\n",
>  		       error);
>  
> -	if (riscv_isa_extension_available(NULL, SSTC)) {
> -		pr_info("Timer interrupt in S-mode is available via sstc extension\n");
> -		static_branch_enable(&riscv_sstc_available);
> -	}
> -
>  	return error;
>  }
>  
> -- 
> 2.30.2
> 
> 
> 
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