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[34.228.114.98]) by smtp.gmail.com with ESMTPSA id af79cd13be357-939e809fd0bsm91246585a.33.2026.09.10.15.46.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2026 15:46:41 -0700 (PDT) Date: Thu, 10 Sep 2026 22:46:38 +0000 Message-ID: From: Josef Bacik To: sashiko-reviews@lists.linux.dev Cc: linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: Re: [PATCH RFC 09/13] arm64: ftrace: Maintain Tasks RCU trampoline nesting in ftrace_caller In-Reply-To: <20260910190436.EBE3A1F000FF@smtp.kernel.org> References: <20260910-b4-rcu-tasks-preempt-qs-v1-0-d4469f4cc101@toxicpanda.com> <20260910-b4-rcu-tasks-preempt-qs-v1-9-d4469f4cc101@toxicpanda.com> <20260910190436.EBE3A1F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Thu, 10 Sep 2026 19:04:36 +0000, sashiko-bot@kernel.org wrote: > > +/* End of [ftrace_caller, ...) for arch_rcu_tasks_ip_in_trampoline(). */ > > +SYM_CODE_START(ftrace_static_tramp_end) > > +SYM_CODE_END(ftrace_static_tramp_end) > > + > > #else /* CONFIG_DYNAMIC_FTRACE_WITH_ARGS */ > > [Severity: Low] > Will this cause a linker error when compiling with > CONFIG_RCU_TASKS_PREEMPT_QS=y but CONFIG_DYNAMIC_FTRACE_WITH_ARGS=n? No, that configuration cannot exist. CONFIG_RCU_TASKS_PREEMPT_QS is def_bool on ARCH_HAS_RCU_TASKS_PREEMPT_QS, and the only place arm64 sets that is in patch 13: select ARCH_HAS_RCU_TASKS_PREEMPT_QS if DYNAMIC_FTRACE_WITH_ARGS so on arm64 RCU_TASKS_PREEMPT_QS=y implies DYNAMIC_FTRACE_WITH_ARGS=y and both the marker in entry-ftrace.S and the arch_rcu_tasks_ip_in_trampoline() that references it are built together or not at all. At this point in the series (patch 9) nothing selects the option yet, so the reference is not built either. For the tool: the two symbols are tied by a Kconfig dependency introduced later in the same series; checking the select conditions across the series would have avoided this one. No change for v2 beyond a note in the changelog. Thanks, Josef