From aa8684755a283536bd8ad93141052f47a4faa5a3 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Tue, 16 Jul 2024 01:29:31 +0800 Subject: [PATCH] workqueue: Remove unneeded lockdep_assert_cpus_held() The commit 19af45757383 ("workqueue: Remove cpus_read_lock() from apply_wqattrs_lock()") removes the unneed cpus_read_lock() after the pwq creations and installations have been reworked based on wq_online_cpumask rather than cpu_online_mask making cpus_read_lock() is unneeded during wqattrs changes. But it desn't remove the lockdep_assert_cpus_held() checks during wqattrs changes, which leads to complaints from lockdep reported by kernel test robot: [ 15.726567][ T131] ------------[ cut here ]------------ [ 15.728117][ T131] WARNING: CPU: 1 PID: 131 at kernel/cpu.c:525 lockdep_assert_cpus_held (kernel/cpu.c:525) [ 15.731191][ T131] Modules linked in: floppy(+) parport_pc(+) parport qemu_fw_cfg rtc_cmos [ 15.733423][ T131] CPU: 1 PID: 131 Comm: systemd-udevd Tainted: G T 6.10.0-rc2-00254-g19af45757383 #1 df6f039f42e8818bf9a534449362ebad1aad32e2 [ 15.737011][ T131] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 [ 15.739760][ T131] EIP: lockdep_assert_cpus_held (kernel/cpu.c:525) [ 15.741326][ T131] Code: 97 c2 03 72 20 83 3d f4 73 97 c2 00 74 17 55 89 e5 b8 fc bd 4d c2 ba ff ff ff ff e8 e4 57 d1 00 85 c0 74 06 5d 31 c0 31 d2 c3 <0f> 0b eb f6 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 89 e5 b8 Fix it by removing the unneeded lockdep_assert_cpus_held(). Also remove the unneed cpus_read_lock() from wq_affn_dfl_set(). tj: Dropped the removal of cpus_read_lock/unlock() in wq_affn_dfl_set() to keep this patch fix only. Cc: kernel test robot Fixes: 19af45757383("workqueue: Remove cpus_read_lock() from apply_wqattrs_lock()") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202407141846.665c0446-lkp@intel.com Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo --- kernel/workqueue.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index dfd42c28e404b9..1745ca788ede3e 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5342,8 +5342,6 @@ static int apply_workqueue_attrs_locked(struct workqueue_struct *wq, * * Performs GFP_KERNEL allocations. * - * Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock(). - * * Return: 0 on success and -errno on failure. */ int apply_workqueue_attrs(struct workqueue_struct *wq, @@ -5351,8 +5349,6 @@ int apply_workqueue_attrs(struct workqueue_struct *wq, { int ret; - lockdep_assert_cpus_held(); - mutex_lock(&wq_pool_mutex); ret = apply_workqueue_attrs_locked(wq, attrs); mutex_unlock(&wq_pool_mutex); @@ -5434,7 +5430,6 @@ static int alloc_and_link_pwqs(struct workqueue_struct *wq) bool highpri = wq->flags & WQ_HIGHPRI; int cpu, ret; - lockdep_assert_cpus_held(); lockdep_assert_held(&wq_pool_mutex); wq->cpu_pwq = alloc_percpu(struct pool_workqueue *); @@ -5695,8 +5690,7 @@ struct workqueue_struct *alloc_workqueue(const char *fmt, /* * wq_pool_mutex protects the workqueues list, allocations of PWQs, - * and the global freeze state. alloc_and_link_pwqs() also requires - * cpus_read_lock() for PWQs' affinities. + * and the global freeze state. */ apply_wqattrs_lock(); @@ -6862,8 +6856,7 @@ static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask) * @exclude_cpumask: the cpumask to be excluded from wq_unbound_cpumask * * This function can be called from cpuset code to provide a set of isolated - * CPUs that should be excluded from wq_unbound_cpumask. The caller must hold - * either cpus_read_lock or cpus_write_lock. + * CPUs that should be excluded from wq_unbound_cpumask. */ int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask) { @@ -6873,7 +6866,6 @@ int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask) if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL)) return -ENOMEM; - lockdep_assert_cpus_held(); mutex_lock(&wq_pool_mutex); /*