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 EA7FD61692 for ; Tue, 13 Feb 2024 18:45:55 +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=1707849957; cv=none; b=GEuOCL0JMwMkKif5VHW47F+hF0L/LK7EFlq/lHBDHavfW4KHAejxRPoFNaMj7exI0QLcR2OXhdoB5Fl8aIpQG47+AeJJTRKbdWEbVXftp9NaSd7eXl7+WvFAKFYjC/RSgHUNmvPV5oTmp73xANOnPqxCjsL/4MFF8ft2uJWCu8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707849957; c=relaxed/simple; bh=s5BgjTafmzNShrIDz3D0IMsmPwUKqJnbt2szR6I5DCo=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=g+oGh4eZkCwPSqnAz1NZXwXWQDVBAO65eoRwRazGW23mjETOA2ezUDrCkyF1shmP3dktyQUxN6IMilTucQzPyykDilSbEwKeomsMbP46OIHI7AHBFXKRux2ifyVvDtW7aOLq/qPRBRN5qO2VvTk4C94tS+xFOR9S6eqHY1cquKA= 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; 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 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 A05BA1596; Tue, 13 Feb 2024 10:46:36 -0800 (PST) Received: from merodach.members.linode.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 45C193F766; Tue, 13 Feb 2024 10:45:52 -0800 (PST) From: James Morse To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Fenghua Yu , Reinette Chatre , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Babu Moger , James Morse , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Babu Moger Subject: [PATCH v9 16/24] x86/resctrl: Make resctrl_mounted checks explicit Date: Tue, 13 Feb 2024 18:44:30 +0000 Message-Id: <20240213184438.16675-17-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20240213184438.16675-1-james.morse@arm.com> References: <20240213184438.16675-1-james.morse@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The rdt_enable_key is switched when resctrl is mounted, and used to prevent a second mount of the filesystem. It also enables the architecture's context switch code. This requires another architecture to have the same set of static-keys, as resctrl depends on them too. The existing users of these static-keys are implicitly also checking if the filesystem is mounted. Make the resctrl_mounted checks explicit: resctrl can keep track of whether it has been mounted once. This doesn't need to be combined with whether the arch code is context switching the CLOSID. rdt_mon_enable_key is never used just to test that resctrl is mounted, but does also have this implication. Add a resctrl_mounted to all uses of rdt_mon_enable_key. This will allow the static-key changing to be moved behind resctrl_arch_ calls. Signed-off-by: James Morse Tested-by: Shaopeng Tan Tested-by: Peter Newman Tested-by: Babu Moger Tested-by: Carl Worth # arm64 Reviewed-by: Shaopeng Tan Reviewed-by: Reinette Chatre Reviewed-by: Babu Moger --- Changes since v3: * Removed a newline. * Rephrased commit message Changes since v4: * Rephrased comment. Changes since v7: * Removed a sentence with the word 'subsequent' in it. --- arch/x86/kernel/cpu/resctrl/internal.h | 1 + arch/x86/kernel/cpu/resctrl/monitor.c | 12 ++++++++++-- arch/x86/kernel/cpu/resctrl/rdtgroup.c | 23 +++++++++++++++++------ 3 files changed, 28 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index e089d1a1a055..9bfda6963794 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -144,6 +144,7 @@ extern bool rdt_alloc_capable; extern bool rdt_mon_capable; extern unsigned int rdt_mon_features; extern struct list_head resctrl_schema_all; +extern bool resctrl_mounted; enum rdt_group_type { RDTCTRL_GROUP = 0, diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 9b503e6ac490..d5d8a58d96f2 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -813,7 +813,11 @@ void mbm_handle_overflow(struct work_struct *work) mutex_lock(&rdtgroup_mutex); - if (!static_branch_likely(&rdt_mon_enable_key)) + /* + * If the filesystem has been unmounted this work no longer needs to + * run. + */ + if (!resctrl_mounted || !static_branch_likely(&rdt_mon_enable_key)) goto out_unlock; r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl; @@ -846,7 +850,11 @@ void mbm_setup_overflow_handler(struct rdt_domain *dom, unsigned long delay_ms) unsigned long delay = msecs_to_jiffies(delay_ms); int cpu; - if (!static_branch_likely(&rdt_mon_enable_key)) + /* + * When a domain comes online there is no guarantee the filesystem is + * mounted. If not, there is no need to catch counter overflow. + */ + if (!resctrl_mounted || !static_branch_likely(&rdt_mon_enable_key)) return; cpu = cpumask_any_housekeeping(&dom->cpu_mask); dom->mbm_work_cpu = cpu; diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index e42cbdf8f6a3..857fbbc3c839 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -42,6 +42,9 @@ LIST_HEAD(rdt_all_groups); /* list of entries for the schemata file */ LIST_HEAD(resctrl_schema_all); +/* The filesystem can only be mounted once. */ +bool resctrl_mounted; + /* Kernel fs node for "info" directory under root */ static struct kernfs_node *kn_info; @@ -881,7 +884,7 @@ int proc_resctrl_show(struct seq_file *s, struct pid_namespace *ns, mutex_lock(&rdtgroup_mutex); /* Return empty if resctrl has not been mounted. */ - if (!static_branch_unlikely(&rdt_enable_key)) { + if (!resctrl_mounted) { seq_puts(s, "res:\nmon:\n"); goto unlock; } @@ -2608,7 +2611,7 @@ static int rdt_get_tree(struct fs_context *fc) /* * resctrl file system can only be mounted once. */ - if (static_branch_unlikely(&rdt_enable_key)) { + if (resctrl_mounted) { ret = -EBUSY; goto out; } @@ -2669,8 +2672,10 @@ static int rdt_get_tree(struct fs_context *fc) if (rdt_mon_capable) static_branch_enable_cpuslocked(&rdt_mon_enable_key); - if (rdt_alloc_capable || rdt_mon_capable) + if (rdt_alloc_capable || rdt_mon_capable) { static_branch_enable_cpuslocked(&rdt_enable_key); + resctrl_mounted = true; + } if (is_mbm_enabled()) { r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl; @@ -2944,6 +2949,7 @@ static void rdt_kill_sb(struct super_block *sb) static_branch_disable_cpuslocked(&rdt_alloc_enable_key); static_branch_disable_cpuslocked(&rdt_mon_enable_key); static_branch_disable_cpuslocked(&rdt_enable_key); + resctrl_mounted = false; kernfs_kill_sb(sb); mutex_unlock(&rdtgroup_mutex); cpus_read_unlock(); @@ -3913,7 +3919,7 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d) * If resctrl is mounted, remove all the * per domain monitor data directories. */ - if (static_branch_unlikely(&rdt_mon_enable_key)) + if (resctrl_mounted && static_branch_unlikely(&rdt_mon_enable_key)) rmdir_mondata_subdir_allrdtgrp(r, d->id); if (is_mbm_enabled()) @@ -3990,8 +3996,13 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d) if (is_llc_occupancy_enabled()) INIT_DELAYED_WORK(&d->cqm_limbo, cqm_handle_limbo); - /* If resctrl is mounted, add per domain monitor data directories. */ - if (static_branch_unlikely(&rdt_mon_enable_key)) + /* + * If the filesystem is not mounted then only the default resource group + * exists. Creation of its directories is deferred until mount time + * by rdt_get_tree() calling mkdir_mondata_all(). + * If resctrl is mounted, add per domain monitor data directories. + */ + if (resctrl_mounted && static_branch_unlikely(&rdt_mon_enable_key)) mkdir_mondata_subdir_allrdtgrp(r, d); return 0; -- 2.39.2