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Cc: Guopeng Zhang , Ridong Chen , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Chen Ridong , Ridong Chen Subject: [RFC PATCH -v4 03/22] cpuset: generalize the validate_partition() interface Date: Sun, 1 Nov 2026 19:41:47 +0800 Message-Id: <20261101114206.2434398-4-ridong.chen@linux.dev> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20261101114206.2434398-1-ridong.chen@linux.dev> References: <20261101114206.2434398-1-ridong.chen@linux.dev> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chen Ridong Refactor validate_partition() to take the parent partition, the new partition root state, the new effective exclusive CPUs and the CPUs to be deleted, instead of a trial cpuset. A NULL parent stands for a remote partition, whose CPUs come from top_cpuset. This makes the interface flexible enough to handle both local and remote partition validation. The housekeeping conflict check is folded into validate_partition(). It is skipped when the parent is not a valid partition root, as @cs can't be a valid local partition in that case. Use the new interface for local partition enablement in update_parent_effective_cpumask() and in partition_cpus_change(), replacing the open-coded checks there. The order of the checks is now the same for both paths: empty CPUs, housekeeping conflict, then no CPU left for tasks. Signed-off-by: Chen Ridong Signed-off-by: Ridong Chen --- kernel/cgroup/cpuset.c | 112 +++++++++++++++++++---------------------- 1 file changed, 52 insertions(+), 60 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index df9fc126e391..df52f6e5e99f 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1438,6 +1438,41 @@ static bool prstate_housekeeping_conflict(int new_prs, int parent_prs, return res; } +/** + * validate_partition - Validate a cpuset partition configuration + * @cs: The cpuset to validate + * @parent: Parent partition of @cs, NULL for remote partition + * @new_prs: The proposed new partition root state + * @new_excpus: The new effective exclusive CPUs mask to validate + * @del: exclusive CPUs to be deleted from @cs, can be NULL + * + * The housekeeping check is skipped if @parent is not a valid partition + * root as @cs can't be a valid local partition in that case. + * + * Return: PRS error code (0 if valid, non-zero error code if invalid) + */ +static enum prs_errcode validate_partition(struct cpuset *cs, + struct cpuset *parent, int new_prs, + struct cpumask *new_excpus, struct cpumask *del) +{ + int parent_prs = parent ? parent->partition_root_state : PRS_ROOT; + + if (new_prs == PRS_MEMBER) + return PERR_NONE; + + if (cpumask_empty(new_excpus)) + return PERR_INVCPUS; + + if ((parent_prs > 0) && + prstate_housekeeping_conflict(new_prs, parent_prs, new_excpus, del)) + return PERR_HKEEPING; + + if (tasks_nocpu_error(parent_cs(cs), cs, new_excpus)) + return PERR_NOCPUS; + + return PERR_NONE; +} + /* * cpuset_update_sd_hk_unlock - Rebuild sched domains, update HK & unlock * @@ -1955,18 +1990,10 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd, if ((cmd == partcmd_enable) || (cmd == partcmd_enablei)) { new_prs = (cmd == partcmd_enable) ? PRS_ROOT : PRS_ISOLATED; - /* - * Enabling partition root is not allowed if its - * effective_xcpus is empty. - */ - if (cpumask_empty(tmp->delmask)) - return PERR_INVCPUS; - - if (prstate_housekeeping_conflict(new_prs, parent_prs, tmp->delmask, NULL)) - return PERR_HKEEPING; - - if (nocpu) - return PERR_NOCPUS; + part_error = validate_partition(cs, parent, new_prs, + tmp->delmask, NULL); + if (part_error) + return part_error; /* * This function will only be called when all the preliminary @@ -2432,32 +2459,6 @@ static int parse_cpuset_cpulist(const char *buf, struct cpumask *out_mask) return 0; } -/** - * validate_partition - Validate a cpuset partition configuration - * @cs: The cpuset to validate - * @trialcs: The trial cpuset containing proposed configuration changes - * - * If any validation check fails, the appropriate error code is set in the - * cpuset's prs_err field. - * - * Return: PRS error code (0 if valid, non-zero error code if invalid) - */ -static enum prs_errcode validate_partition(struct cpuset *cs, struct cpuset *trialcs) -{ - struct cpuset *parent = parent_cs(cs); - - if (cs_is_member(trialcs)) - return PERR_NONE; - - if (cpumask_empty(trialcs->effective_xcpus)) - return PERR_INVCPUS; - - if (tasks_nocpu_error(parent, cs, trialcs->effective_xcpus)) - return PERR_NOCPUS; - - return PERR_NONE; -} - /** * partition_cpus_change - Handle partition state changes due to CPU mask updates * @cs: The target cpuset being modified @@ -2471,33 +2472,24 @@ static void partition_cpus_change(struct cpuset *cs, struct cpuset *trialcs, struct tmpmasks *tmp) { enum prs_errcode prs_err; - int parent_prs = is_remote_partition(cs) - ? PRS_ROOT : parent_cs(cs)->partition_root_state; + struct cpuset *parent = is_remote_partition(cs) ? NULL : parent_cs(cs); if (cs_is_member(cs)) return; - prs_err = validate_partition(cs, trialcs); - if (!prs_err && (parent_prs > 0) && - !cpumask_empty(trialcs->effective_xcpus)) { - int prs = cs->partition_root_state; - - /* - * Check for housekeeping conflict by passing the whole - * effective_xcpus as well as those CPUs that are to be - * removed from cs as delmask. - */ - if (prs > 0) - cpumask_andnot(tmp->delmask, cs->effective_xcpus, - trialcs->effective_xcpus); - else - cpumask_clear(tmp->delmask); - - if (prstate_housekeeping_conflict(prs, parent_prs, - trialcs->effective_xcpus, tmp->delmask)) - prs_err = PERR_HKEEPING; - } + /* + * Check for housekeeping conflict by passing the whole + * effective_xcpus as well as those CPUs that are to be + * removed from cs as delmask. + */ + if (is_partition_valid(cs)) + cpumask_andnot(tmp->delmask, cs->effective_xcpus, + trialcs->effective_xcpus); + else + cpumask_clear(tmp->delmask); + prs_err = validate_partition(cs, parent, trialcs->partition_root_state, + trialcs->effective_xcpus, tmp->delmask); if (prs_err) { WRITE_ONCE(cs->prs_err, prs_err); trialcs->prs_err = prs_err; -- 2.34.1