From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 4EAF1437467 for ; Wed, 2 Sep 2026 10:16:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788344206; cv=none; b=T1E5hltNzmB8ecO9sDjfk8fX5ZD51FebZi5S6fcVKItjmL56hN9crn4yWXeU3bsedmJ2Bd814Y9kBEDWQ5Pfju/B/X86tIGg5WuYmBCuWhbNinkafL+2hM+gdUByb5PFW/QeMEFIzcg6r8Q9/AW8x7s6to0qX75xaX13o0V122I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788344206; c=relaxed/simple; bh=fFPGFWI402zKV2/sKWo875KorlNQL9YoQRPKk7KcXk4=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=rbBTIOkEIeDutQMxQfWPyLlx59+fWykfXwvxnICCbGyjWgStyniyav1iVEGHL9RvVmbzM/73oU9hq/CBvlhooINg5dQnObsj0Svzg0XBoTcVe1f/nhbN6n+LnVvMstmbyiJqzTYq5adBqabPp2Mrb1hbSZn0P/xXdoCTe+BE5jw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=WqX946np; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="WqX946np" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E776C165C; Wed, 2 Sep 2026 03:16:40 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id A0B0B3F882; Wed, 2 Sep 2026 03:16:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1788344204; bh=fFPGFWI402zKV2/sKWo875KorlNQL9YoQRPKk7KcXk4=; h=From:To:Cc:Subject:Date:From; b=WqX946np0NusNKATxBg446tNVXONDI79hj6bYydosZzUyqKN7pjc6Z7TNeApdtWFo X1XoXsIntzUPW7JMG8joYhxdlprBHVhYeeu8ktrozk6taUDnD/WA/At3MYxPVVMOUu tZElLyTuPXYnmUkCaqg8KIByKSPr3o1ZGPoYlj24= From: Mark Rutland To: linux-kernel@vger.kernel.org, Peter Zijlstra Cc: mark.rutland@arm.com, meted@linux.ibm.com, ruanjinjie@huawei.com, sshegde@linux.ibm.com Subject: [PATCH] sched: dynamic: Fix preemption model strings Date: Wed, 2 Sep 2026 11:16:37 +0100 Message-Id: <20260902101637.232129-1-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit We recently removed the enum values 'preempt_dynamic_none' and 'preempt_dynamic_voluntary', but forgot to update preempt_modes[] accordingly. Due to this, preempt_model_str() and sched_dynamic_show() produce incorrect output, with the wrong preemption model string in backtraces, and empty output for /sys/kernel/debug/sched/preempt. Update preempt_modes[] to account for the removed enum values. Given that CONFIG_PREEMPT_DYNAMIC now depends on CONFIG_ARCH_HAS_PREEMPT_LAZY, and given that only 'preempt_dynamic_full' and 'preempt_dynamic_lazy' remain, sched_dynamic_show() no longer needs to skip any model strings. Reported-by: Jinjie Ruan Fixes: 9650ce11f2e3 ("sched: dynamic: Simplify preempt model accessors") Signed-off-by: Mark Rutland Cc: Mete Durlu Cc: Peter Zijlstra Cc: Shrikanth Hegde --- kernel/sched/core.c | 2 +- kernel/sched/debug.c | 10 ++-------- 2 files changed, 3 insertions(+), 9 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 545f49491bcde..5a61650f12b7d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7960,7 +7960,7 @@ static inline void preempt_dynamic_init(void) { } #endif /* CONFIG_PREEMPT_DYNAMIC */ const char *preempt_modes[] = { - "none", "voluntary", "full", "lazy", NULL, + "full", "lazy", NULL, }; const char *preempt_model_str(void) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 9883e4c4976bf..fda10b3fa249a 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -280,16 +280,10 @@ static ssize_t sched_dynamic_write(struct file *filp, const char __user *ubuf, static int sched_dynamic_show(struct seq_file *m, void *v) { - int i = (IS_ENABLED(CONFIG_PREEMPT_RT) || IS_ENABLED(CONFIG_ARCH_HAS_PREEMPT_LAZY)) * 2; int mode = READ_ONCE(preempt_dynamic_mode); - int j; - /* Count entries in NULL terminated preempt_modes */ - for (j = 0; preempt_modes[j]; j++) - ; - j -= !IS_ENABLED(CONFIG_ARCH_HAS_PREEMPT_LAZY); - - for (; i < j; i++) { + /* Stop at NULL terminator */ + for (int i = 0; preempt_modes[i]; i++) { if (mode == i) seq_puts(m, "("); seq_puts(m, preempt_modes[i]); -- 2.30.2