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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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workqueue: prepare for WQ_UNBOUND implementation
In preparation of WQ_UNBOUND addition, make the following changes. * Add WORK_CPU_* constants for pseudo cpu id numbers used (currently only WORK_CPU_NONE) and use them instead of NR_CPUS. This is to allow another pseudo cpu id for unbound cpu. * Reorder WQ_* flags. * Make workqueue_struct->cpu_wq a union which contains a percpu pointer, regular pointer and an unsigned long value and use kzalloc/kfree() in UP allocation path. This will be used to implement unbound workqueues which will use only one cwq on SMPs. * Move alloc_cwqs() allocation after initialization of wq fields, so that alloc_cwqs() has access to wq->flags. * Trivial relocation of wq local variables in freeze functions. These changes don't cause any functional change. Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo
parent
ad72cf9885
commit
bdbc5dd7de
@ -50,6 +50,10 @@ enum {
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WORK_NR_COLORS = (1 << WORK_STRUCT_COLOR_BITS) - 1,
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WORK_NO_COLOR = WORK_NR_COLORS,
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/* special cpu IDs */
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WORK_CPU_NONE = NR_CPUS,
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WORK_CPU_LAST = WORK_CPU_NONE,
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/*
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* Reserve 6 bits off of cwq pointer w/ debugobjects turned
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* off. This makes cwqs aligned to 64 bytes which isn't too
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@ -60,7 +64,7 @@ enum {
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WORK_STRUCT_FLAG_MASK = (1UL << WORK_STRUCT_FLAG_BITS) - 1,
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WORK_STRUCT_WQ_DATA_MASK = ~WORK_STRUCT_FLAG_MASK,
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WORK_STRUCT_NO_CPU = NR_CPUS << WORK_STRUCT_FLAG_BITS,
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WORK_STRUCT_NO_CPU = WORK_CPU_NONE << WORK_STRUCT_FLAG_BITS,
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/* bit mask for work_busy() return values */
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WORK_BUSY_PENDING = 1 << 0,
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@ -227,9 +231,9 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
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clear_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))
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enum {
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WQ_FREEZEABLE = 1 << 0, /* freeze during suspend */
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WQ_NON_REENTRANT = 1 << 0, /* guarantee non-reentrance */
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WQ_SINGLE_CPU = 1 << 1, /* only single cpu at a time */
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WQ_NON_REENTRANT = 1 << 2, /* guarantee non-reentrance */
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WQ_FREEZEABLE = 1 << 2, /* freeze during suspend */
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WQ_RESCUER = 1 << 3, /* has an rescue worker */
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WQ_HIGHPRI = 1 << 4, /* high priority */
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WQ_CPU_INTENSIVE = 1 << 5, /* cpu instensive workqueue */
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@ -190,7 +190,11 @@ struct wq_flusher {
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*/
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struct workqueue_struct {
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unsigned int flags; /* I: WQ_* flags */
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struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */
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union {
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struct cpu_workqueue_struct __percpu *pcpu;
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struct cpu_workqueue_struct *single;
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unsigned long v;
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} cpu_wq; /* I: cwq's */
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struct list_head list; /* W: list of all workqueues */
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struct mutex flush_mutex; /* protects wq flushing */
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@ -362,7 +366,11 @@ static atomic_t *get_gcwq_nr_running(unsigned int cpu)
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static struct cpu_workqueue_struct *get_cwq(unsigned int cpu,
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struct workqueue_struct *wq)
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{
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return per_cpu_ptr(wq->cpu_wq, cpu);
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#ifndef CONFIG_SMP
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return wq->cpu_wq.single;
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#else
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return per_cpu_ptr(wq->cpu_wq.pcpu, cpu);
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#endif
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}
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static unsigned int work_color_to_flags(int color)
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@ -442,7 +450,7 @@ static struct global_cwq *get_work_gcwq(struct work_struct *work)
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return ((struct cpu_workqueue_struct *)data)->gcwq;
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cpu = data >> WORK_STRUCT_FLAG_BITS;
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if (cpu == NR_CPUS)
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if (cpu == WORK_CPU_NONE)
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return NULL;
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BUG_ON(cpu >= nr_cpu_ids);
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@ -846,7 +854,7 @@ static void cwq_unbind_single_cpu(struct cpu_workqueue_struct *cwq)
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*/
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if (likely(!(gcwq->flags & GCWQ_FREEZING))) {
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smp_wmb(); /* paired with cmpxchg() in __queue_work() */
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wq->single_cpu = NR_CPUS;
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wq->single_cpu = WORK_CPU_NONE;
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}
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}
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@ -904,7 +912,7 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
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*/
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retry:
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cpu = wq->single_cpu;
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arbitrate = cpu == NR_CPUS;
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arbitrate = cpu == WORK_CPU_NONE;
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if (arbitrate)
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cpu = req_cpu;
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@ -918,7 +926,7 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
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* visible on the new cpu after this point.
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*/
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if (arbitrate)
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cmpxchg(&wq->single_cpu, NR_CPUS, cpu);
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cmpxchg(&wq->single_cpu, WORK_CPU_NONE, cpu);
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if (unlikely(wq->single_cpu != cpu)) {
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spin_unlock_irqrestore(&gcwq->lock, flags);
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@ -2572,7 +2580,7 @@ int keventd_up(void)
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return system_wq != NULL;
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}
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static struct cpu_workqueue_struct *alloc_cwqs(void)
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static int alloc_cwqs(struct workqueue_struct *wq)
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{
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/*
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* cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
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@ -2582,40 +2590,36 @@ static struct cpu_workqueue_struct *alloc_cwqs(void)
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const size_t size = sizeof(struct cpu_workqueue_struct);
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const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS,
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__alignof__(unsigned long long));
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struct cpu_workqueue_struct *cwqs;
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#ifndef CONFIG_SMP
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void *ptr;
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/*
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* On UP, percpu allocator doesn't honor alignment parameter
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* and simply uses arch-dependent default. Allocate enough
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* room to align cwq and put an extra pointer at the end
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* pointing back to the originally allocated pointer which
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* will be used for free.
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*
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* FIXME: This really belongs to UP percpu code. Update UP
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* percpu code to honor alignment and remove this ugliness.
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* Allocate enough room to align cwq and put an extra pointer
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* at the end pointing back to the originally allocated
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* pointer which will be used for free.
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*/
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ptr = __alloc_percpu(size + align + sizeof(void *), 1);
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cwqs = PTR_ALIGN(ptr, align);
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*(void **)per_cpu_ptr(cwqs + 1, 0) = ptr;
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ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL);
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if (ptr) {
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wq->cpu_wq.single = PTR_ALIGN(ptr, align);
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*(void **)(wq->cpu_wq.single + 1) = ptr;
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}
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#else
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/* On SMP, percpu allocator can do it itself */
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cwqs = __alloc_percpu(size, align);
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/* On SMP, percpu allocator can align itself */
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wq->cpu_wq.pcpu = __alloc_percpu(size, align);
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#endif
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/* just in case, make sure it's actually aligned */
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BUG_ON(!IS_ALIGNED((unsigned long)cwqs, align));
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return cwqs;
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BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align));
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return wq->cpu_wq.v ? 0 : -ENOMEM;
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}
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static void free_cwqs(struct cpu_workqueue_struct *cwqs)
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static void free_cwqs(struct workqueue_struct *wq)
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{
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#ifndef CONFIG_SMP
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/* on UP, the pointer to free is stored right after the cwq */
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if (cwqs)
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free_percpu(*(void **)per_cpu_ptr(cwqs + 1, 0));
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if (wq->cpu_wq.single)
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kfree(*(void **)(wq->cpu_wq.single + 1));
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#else
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free_percpu(cwqs);
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free_percpu(wq->cpu_wq.pcpu);
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#endif
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}
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@ -2645,22 +2649,21 @@ struct workqueue_struct *__alloc_workqueue_key(const char *name,
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if (!wq)
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goto err;
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wq->cpu_wq = alloc_cwqs();
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if (!wq->cpu_wq)
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goto err;
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wq->flags = flags;
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wq->saved_max_active = max_active;
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mutex_init(&wq->flush_mutex);
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atomic_set(&wq->nr_cwqs_to_flush, 0);
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INIT_LIST_HEAD(&wq->flusher_queue);
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INIT_LIST_HEAD(&wq->flusher_overflow);
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wq->single_cpu = NR_CPUS;
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wq->single_cpu = WORK_CPU_NONE;
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wq->name = name;
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lockdep_init_map(&wq->lockdep_map, lock_name, key, 0);
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INIT_LIST_HEAD(&wq->list);
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if (alloc_cwqs(wq) < 0)
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goto err;
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for_each_possible_cpu(cpu) {
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struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq);
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struct global_cwq *gcwq = get_gcwq(cpu);
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@ -2710,7 +2713,7 @@ struct workqueue_struct *__alloc_workqueue_key(const char *name,
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return wq;
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err:
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if (wq) {
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free_cwqs(wq->cpu_wq);
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free_cwqs(wq);
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free_cpumask_var(wq->mayday_mask);
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kfree(wq->rescuer);
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kfree(wq);
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@ -2755,7 +2758,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
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free_cpumask_var(wq->mayday_mask);
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}
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free_cwqs(wq->cpu_wq);
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free_cwqs(wq);
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kfree(wq);
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}
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EXPORT_SYMBOL_GPL(destroy_workqueue);
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@ -2821,13 +2824,13 @@ EXPORT_SYMBOL_GPL(workqueue_congested);
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* @work: the work of interest
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*
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* RETURNS:
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* CPU number if @work was ever queued. NR_CPUS otherwise.
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* CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
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*/
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unsigned int work_cpu(struct work_struct *work)
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{
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struct global_cwq *gcwq = get_work_gcwq(work);
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return gcwq ? gcwq->cpu : NR_CPUS;
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return gcwq ? gcwq->cpu : WORK_CPU_NONE;
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}
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EXPORT_SYMBOL_GPL(work_cpu);
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@ -3300,7 +3303,6 @@ EXPORT_SYMBOL_GPL(work_on_cpu);
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*/
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void freeze_workqueues_begin(void)
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{
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struct workqueue_struct *wq;
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unsigned int cpu;
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spin_lock(&workqueue_lock);
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@ -3310,6 +3312,7 @@ void freeze_workqueues_begin(void)
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for_each_possible_cpu(cpu) {
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struct global_cwq *gcwq = get_gcwq(cpu);
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struct workqueue_struct *wq;
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spin_lock_irq(&gcwq->lock);
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@ -3344,7 +3347,6 @@ void freeze_workqueues_begin(void)
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*/
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bool freeze_workqueues_busy(void)
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{
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struct workqueue_struct *wq;
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unsigned int cpu;
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bool busy = false;
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@ -3353,6 +3355,7 @@ bool freeze_workqueues_busy(void)
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BUG_ON(!workqueue_freezing);
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for_each_possible_cpu(cpu) {
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struct workqueue_struct *wq;
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/*
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* nr_active is monotonically decreasing. It's safe
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* to peek without lock.
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@ -3386,7 +3389,6 @@ bool freeze_workqueues_busy(void)
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*/
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void thaw_workqueues(void)
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{
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struct workqueue_struct *wq;
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unsigned int cpu;
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spin_lock(&workqueue_lock);
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@ -3396,6 +3398,7 @@ void thaw_workqueues(void)
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for_each_possible_cpu(cpu) {
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struct global_cwq *gcwq = get_gcwq(cpu);
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struct workqueue_struct *wq;
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spin_lock_irq(&gcwq->lock);
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@ -3443,7 +3446,7 @@ void __init init_workqueues(void)
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* sure cpu number won't overflow into kernel pointer area so
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* that they can be distinguished.
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*/
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BUILD_BUG_ON(NR_CPUS << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET);
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BUILD_BUG_ON(WORK_CPU_LAST << WORK_STRUCT_FLAG_BITS >= PAGE_OFFSET);
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hotcpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE);
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