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[36.225.97.241]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-361419739dfsm14549188a91.13.2026.04.21.06.49.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2026 06:49:16 -0700 (PDT) Date: Tue, 21 Apr 2026 21:49:12 +0800 From: Cheng-Yang Chou To: Tejun Heo Cc: void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, sched-ext@lists.linux.dev, emil@etsalapatis.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/16] sched_ext: Shift scx_kick_cpu() validity check to scx_bpf_kick_cpu() Message-ID: <20260421213729.Gb2f6@cchengyang.duckdns.org> References: <20260421071945.3110084-1-tj@kernel.org> <20260421071945.3110084-4-tj@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260421071945.3110084-4-tj@kernel.org> Hi Tejun, On Mon, Apr 20, 2026 at 09:19:32PM -1000, Tejun Heo wrote: > Callers that already know the cpu is valid shouldn't have to pay for a > redundant check. scx_kick_cpu() is called from the in-kernel balance loop > break-out path with the current cpu (trivially valid) and from > scx_bpf_kick_cpu() with a BPF-supplied cpu that does need validation. Move > the check out of scx_kick_cpu() into scx_bpf_kick_cpu() so the backend is > reusable by callers that have already validated. > > Signed-off-by: Tejun Heo > --- > kernel/sched/ext.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c > index 5571f5995dd8..9e802d73f205 100644 > --- a/kernel/sched/ext.c > +++ b/kernel/sched/ext.c > @@ -8673,9 +8673,6 @@ static void scx_kick_cpu(struct scx_sched *sch, s32 cpu, u64 flags) > struct rq *this_rq; > unsigned long irq_flags; > > - if (!scx_cpu_valid(sch, cpu, NULL)) > - return; > - > local_irq_save(irq_flags); I initially think of removing the guard here would left a gap, but patch 10's scx_bpf_kick_cid covers it, so Reviewed-by: Cheng-Yang Chou > > this_rq = this_rq(); > @@ -8738,7 +8735,7 @@ __bpf_kfunc void scx_bpf_kick_cpu(s32 cpu, u64 flags, const struct bpf_prog_aux > > guard(rcu)(); > sch = scx_prog_sched(aux); > - if (likely(sch)) > + if (likely(sch) && scx_cpu_valid(sch, cpu, NULL)) > scx_kick_cpu(sch, cpu, flags); > } > > -- > 2.53.0 > > -- Cheers, Cheng-Yang