Re: [PATCH v4 2/2] rethook: honor CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING in rethook_try_get()

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Apr 18, 2024 at 12:09:09PM -0700, Andrii Nakryiko wrote:
> Take into account CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING when validating
> that RCU is watching when trying to setup rethooko on a function entry.
> 
> One notable exception when we force rcu_is_watching() check is
> CONFIG_KPROBE_EVENTS_ON_NOTRACE=y case, in which case kretprobes will use
> old-style int3-based workflow instead of relying on ftrace, making RCU
> watching check important to validate.
> 
> This further (in addition to improvements in the previous patch)
> improves BPF multi-kretprobe (which rely on rethook) runtime throughput
> by 2.3%, according to BPF benchmarks ([0]).
> 
>   [0] https://lore.kernel.org/bpf/CAEf4BzauQ2WKMjZdc9s0rBWa01BYbgwHN6aNDXQSHYia47pQ-w@xxxxxxxxxxxxxx/
> 
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>

Acked-by: Paul E. McKenney <paulmck@xxxxxxxxxx>

> ---
>  kernel/trace/rethook.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
> index fa03094e9e69..a974605ad7a5 100644
> --- a/kernel/trace/rethook.c
> +++ b/kernel/trace/rethook.c
> @@ -166,6 +166,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh)
>  	if (unlikely(!handler))
>  		return NULL;
>  
> +#if defined(CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING) || defined(CONFIG_KPROBE_EVENTS_ON_NOTRACE)
>  	/*
>  	 * This expects the caller will set up a rethook on a function entry.
>  	 * When the function returns, the rethook will eventually be reclaimed
> @@ -174,6 +175,7 @@ struct rethook_node *rethook_try_get(struct rethook *rh)
>  	 */
>  	if (unlikely(!rcu_is_watching()))
>  		return NULL;
> +#endif
>  
>  	return (struct rethook_node *)objpool_pop(&rh->pool);
>  }
> -- 
> 2.43.0
> 




[Index of Archives]     [Linux Samsung SoC]     [Linux Rockchip SoC]     [Linux Actions SoC]     [Linux for Synopsys ARC Processors]     [Linux NFS]     [Linux NILFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]


  Powered by Linux