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Merge branch 'for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

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Pull workqueue updates from Tejun Heo:

 - make kworkers report the workqueue it is executing or has executed
   most recently in /proc/PID/comm (so they show up in ps/top)

 - CONFIG_SMP shuffle to move stuff which isn't necessary for UP builds
   inside CONFIG_SMP.

* 'for-4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: move function definitions within CONFIG_SMP block
  workqueue: Make sure struct worker is accessible for wq_worker_comm()
  workqueue: Show the latest workqueue name in /proc/PID/{comm,stat,status}
  proc: Consolidate task->comm formatting into proc_task_name()
  workqueue: Set worker->desc to workqueue name by default
  workqueue: Make worker_attach/detach_pool() update worker->pool
  workqueue: Replace pool->attach_mutex with global wq_pool_attach_mutex
This commit is contained in:
Linus Torvalds 2018-06-05 17:31:33 -07:00
commit af6c5d5e01
6 changed files with 119 additions and 64 deletions
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33
fs/proc/array.c
View File

@ -96,22 +96,29 @@
#include <asm/processor.h>
#include "internal.h"
static inline void task_name(struct seq_file *m, struct task_struct *p)
void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
{
char *buf;
size_t size;
char tcomm[sizeof(p->comm)];
char tcomm[64];
int ret;
get_task_comm(tcomm, p);
seq_puts(m, "Name:\t");
if (p->flags & PF_WQ_WORKER)
wq_worker_comm(tcomm, sizeof(tcomm), p);
else
__get_task_comm(tcomm, sizeof(tcomm), p);
size = seq_get_buf(m, &buf);
ret = string_escape_str(tcomm, buf, size, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
seq_commit(m, ret < size ? ret : -1);
if (escape) {
ret = string_escape_str(tcomm, buf, size,
ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
if (ret >= size)
ret = -1;
} else {
ret = strscpy(buf, tcomm, size);
}
seq_putc(m, '\n');
seq_commit(m, ret);
}
/*
@ -390,7 +397,10 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
{
struct mm_struct *mm = get_task_mm(task);
task_name(m, task);
seq_puts(m, "Name:\t");
proc_task_name(m, task, true);
seq_putc(m, '\n');
task_state(m, ns, pid, task);
if (mm) {
@ -425,7 +435,6 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
u64 cutime, cstime, utime, stime;
u64 cgtime, gtime;
unsigned long rsslim = 0;
char tcomm[sizeof(task->comm)];
unsigned long flags;
state = *get_task_state(task);
@ -452,8 +461,6 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
}
}
get_task_comm(tcomm, task);
sigemptyset(&sigign);
sigemptyset(&sigcatch);
cutime = cstime = utime = stime = 0;
@ -520,7 +527,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
seq_put_decimal_ull(m, "", pid_nr_ns(pid, ns));
seq_puts(m, " (");
seq_puts(m, tcomm);
proc_task_name(m, task, false);
seq_puts(m, ") ");
seq_putc(m, state);
seq_put_decimal_ll(m, " ", ppid);

5
fs/proc/base.c
View File

@ -1563,9 +1563,8 @@ static int comm_show(struct seq_file *m, void *v)
if (!p)
return -ESRCH;
task_lock(p);
seq_printf(m, "%s\n", p->comm);
task_unlock(p);
proc_task_name(m, p, false);
seq_putc(m, '\n');
put_task_struct(p);

2
fs/proc/internal.h
View File

@ -136,6 +136,8 @@ unsigned name_to_int(const struct qstr *qstr);
*/
extern const struct file_operations proc_tid_children_operations;
extern void proc_task_name(struct seq_file *m, struct task_struct *p,
bool escape);
extern int proc_tid_stat(struct seq_file *, struct pid_namespace *,
struct pid *, struct task_struct *);
extern int proc_tgid_stat(struct seq_file *, struct pid_namespace *,

1
include/linux/workqueue.h
View File

@ -494,6 +494,7 @@ extern unsigned int work_busy(struct work_struct *work);
extern __printf(1, 2) void set_worker_desc(const char *fmt, ...);
extern void print_worker_info(const char *log_lvl, struct task_struct *task);
extern void show_workqueue_state(void);
extern void wq_worker_comm(char *buf, size_t size, struct task_struct *task);
/**
* queue_work - queue work on a workqueue

139
kernel/workqueue.c
View File

@ -66,7 +66,7 @@ enum {
* be executing on any CPU. The pool behaves as an unbound one.
*
* Note that DISASSOCIATED should be flipped only while holding
* attach_mutex to avoid changing binding state while
* wq_pool_attach_mutex to avoid changing binding state while
* worker_attach_to_pool() is in progress.
*/
POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */
@ -123,7 +123,7 @@ enum {
* cpu or grabbing pool->lock is enough for read access. If
* POOL_DISASSOCIATED is set, it's identical to L.
*
* A: pool->attach_mutex protected.
* A: wq_pool_attach_mutex protected.
*
* PL: wq_pool_mutex protected.
*
@ -166,7 +166,6 @@ struct worker_pool {
/* L: hash of busy workers */
struct worker *manager; /* L: purely informational */
struct mutex attach_mutex; /* attach/detach exclusion */
struct list_head workers; /* A: attached workers */
struct completion *detach_completion; /* all workers detached */
@ -297,6 +296,7 @@ static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */
static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
static DECLARE_WAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */
@ -399,14 +399,14 @@ static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
* @worker: iteration cursor
* @pool: worker_pool to iterate workers of
*
* This must be called with @pool->attach_mutex.
* This must be called with wq_pool_attach_mutex.
*
* The if/else clause exists only for the lockdep assertion and can be
* ignored.
*/
#define for_each_pool_worker(worker, pool) \
list_for_each_entry((worker), &(pool)->workers, node) \
if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \
if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \
else
/**
@ -1724,7 +1724,7 @@ static struct worker *alloc_worker(int node)
static void worker_attach_to_pool(struct worker *worker,
struct worker_pool *pool)
{
mutex_lock(&pool->attach_mutex);
mutex_lock(&wq_pool_attach_mutex);
/*
* set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
@ -1733,37 +1733,40 @@ static void worker_attach_to_pool(struct worker *worker,
set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
/*
* The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
* stable across this function. See the comments above the
* flag definition for details.
* The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains
* stable across this function. See the comments above the flag
* definition for details.
*/
if (pool->flags & POOL_DISASSOCIATED)
worker->flags |= WORKER_UNBOUND;
list_add_tail(&worker->node, &pool->workers);
worker->pool = pool;
mutex_unlock(&pool->attach_mutex);
mutex_unlock(&wq_pool_attach_mutex);
}
/**
* worker_detach_from_pool() - detach a worker from its pool
* @worker: worker which is attached to its pool
* @pool: the pool @worker is attached to
*
* Undo the attaching which had been done in worker_attach_to_pool(). The
* caller worker shouldn't access to the pool after detached except it has
* other reference to the pool.
*/
static void worker_detach_from_pool(struct worker *worker,
struct worker_pool *pool)
static void worker_detach_from_pool(struct worker *worker)
{
struct worker_pool *pool = worker->pool;
struct completion *detach_completion = NULL;
mutex_lock(&pool->attach_mutex);
mutex_lock(&wq_pool_attach_mutex);
list_del(&worker->node);
worker->pool = NULL;
if (list_empty(&pool->workers))
detach_completion = pool->detach_completion;
mutex_unlock(&pool->attach_mutex);
mutex_unlock(&wq_pool_attach_mutex);
/* clear leftover flags without pool->lock after it is detached */
worker->flags &= ~(WORKER_UNBOUND | WORKER_REBOUND);
@ -1799,7 +1802,6 @@ static struct worker *create_worker(struct worker_pool *pool)
if (!worker)
goto fail;
worker->pool = pool;
worker->id = id;
if (pool->cpu >= 0)
@ -2086,6 +2088,12 @@ __acquires(&pool->lock)
worker->current_pwq = pwq;
work_color = get_work_color(work);
/*
* Record wq name for cmdline and debug reporting, may get
* overridden through set_worker_desc().
*/
strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN);
list_del_init(&work->entry);
/*
@ -2181,7 +2189,6 @@ __acquires(&pool->lock)
worker->current_work = NULL;
worker->current_func = NULL;
worker->current_pwq = NULL;
worker->desc_valid = false;
pwq_dec_nr_in_flight(pwq, work_color);
}
@ -2206,6 +2213,16 @@ static void process_scheduled_works(struct worker *worker)
}
}
static void set_pf_worker(bool val)
{
mutex_lock(&wq_pool_attach_mutex);
if (val)
current->flags |= PF_WQ_WORKER;
else
current->flags &= ~PF_WQ_WORKER;
mutex_unlock(&wq_pool_attach_mutex);
}
/**
* worker_thread - the worker thread function
* @__worker: self
@ -2224,7 +2241,7 @@ static int worker_thread(void *__worker)
struct worker_pool *pool = worker->pool;
/* tell the scheduler that this is a workqueue worker */
worker->task->flags |= PF_WQ_WORKER;
set_pf_worker(true);
woke_up:
spin_lock_irq(&pool->lock);
@ -2232,11 +2249,11 @@ static int worker_thread(void *__worker)
if (unlikely(worker->flags & WORKER_DIE)) {
spin_unlock_irq(&pool->lock);
WARN_ON_ONCE(!list_empty(&worker->entry));
worker->task->flags &= ~PF_WQ_WORKER;
set_pf_worker(false);
set_task_comm(worker->task, "kworker/dying");
ida_simple_remove(&pool->worker_ida, worker->id);
worker_detach_from_pool(worker, pool);
worker_detach_from_pool(worker);
kfree(worker);
return 0;
}
@ -2335,7 +2352,7 @@ static int rescuer_thread(void *__rescuer)
* Mark rescuer as worker too. As WORKER_PREP is never cleared, it
* doesn't participate in concurrency management.
*/
rescuer->task->flags |= PF_WQ_WORKER;
set_pf_worker(true);
repeat:
set_current_state(TASK_IDLE);
@ -2367,7 +2384,6 @@ static int rescuer_thread(void *__rescuer)
worker_attach_to_pool(rescuer, pool);
spin_lock_irq(&pool->lock);
rescuer->pool = pool;
/*
* Slurp in all works issued via this workqueue and
@ -2417,10 +2433,9 @@ static int rescuer_thread(void *__rescuer)
if (need_more_worker(pool))
wake_up_worker(pool);
rescuer->pool = NULL;
spin_unlock_irq(&pool->lock);
worker_detach_from_pool(rescuer, pool);
worker_detach_from_pool(rescuer);
spin_lock_irq(&wq_mayday_lock);
}
@ -2429,7 +2444,7 @@ static int rescuer_thread(void *__rescuer)
if (should_stop) {
__set_current_state(TASK_RUNNING);
rescuer->task->flags &= ~PF_WQ_WORKER;
set_pf_worker(false);
return 0;
}
@ -3271,7 +3286,6 @@ static int init_worker_pool(struct worker_pool *pool)
timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0);
mutex_init(&pool->attach_mutex);
INIT_LIST_HEAD(&pool->workers);
ida_init(&pool->worker_ida);
@ -3354,10 +3368,10 @@ static void put_unbound_pool(struct worker_pool *pool)
WARN_ON(pool->nr_workers || pool->nr_idle);
spin_unlock_irq(&pool->lock);
mutex_lock(&pool->attach_mutex);
mutex_lock(&wq_pool_attach_mutex);
if (!list_empty(&pool->workers))
pool->detach_completion = &detach_completion;
mutex_unlock(&pool->attach_mutex);
mutex_unlock(&wq_pool_attach_mutex);
if (pool->detach_completion)
wait_for_completion(pool->detach_completion);
@ -4347,7 +4361,6 @@ void set_worker_desc(const char *fmt, ...)
va_start(args, fmt);
vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
va_end(args);
worker->desc_valid = true;
}
}
@ -4371,7 +4384,6 @@ void print_worker_info(const char *log_lvl, struct task_struct *task)
char desc[WORKER_DESC_LEN] = { };
struct pool_workqueue *pwq = NULL;
struct workqueue_struct *wq = NULL;
bool desc_valid = false;
struct worker *worker;
if (!(task->flags & PF_WQ_WORKER))
@ -4384,22 +4396,18 @@ void print_worker_info(const char *log_lvl, struct task_struct *task)
worker = kthread_probe_data(task);
/*
* Carefully copy the associated workqueue's workfn and name. Keep
* the original last '\0' in case the original contains garbage.
* Carefully copy the associated workqueue's workfn, name and desc.
* Keep the original last '\0' in case the original is garbage.
*/
probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
probe_kernel_read(name, wq->name, sizeof(name) - 1);
/* copy worker description */
probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid));
if (desc_valid)
probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
if (fn || name[0] || desc[0]) {
printk("%sWorkqueue: %s %pf", log_lvl, name, fn);
if (desc[0])
if (strcmp(name, desc))
pr_cont(" (%s)", desc);
pr_cont("\n");
}
@ -4579,6 +4587,47 @@ void show_workqueue_state(void)
rcu_read_unlock_sched();
}
/* used to show worker information through /proc/PID/{comm,stat,status} */
void wq_worker_comm(char *buf, size_t size, struct task_struct *task)
{
int off;
/* always show the actual comm */
off = strscpy(buf, task->comm, size);
if (off < 0)
return;
/* stabilize PF_WQ_WORKER and worker pool association */
mutex_lock(&wq_pool_attach_mutex);
if (task->flags & PF_WQ_WORKER) {
struct worker *worker = kthread_data(task);
struct worker_pool *pool = worker->pool;
if (pool) {
spin_lock_irq(&pool->lock);
/*
* ->desc tracks information (wq name or
* set_worker_desc()) for the latest execution. If
* current, prepend '+', otherwise '-'.
*/
if (worker->desc[0] != '\0') {
if (worker->current_work)
scnprintf(buf + off, size - off, "+%s",
worker->desc);
else
scnprintf(buf + off, size - off, "-%s",
worker->desc);
}
spin_unlock_irq(&pool->lock);
}
}
mutex_unlock(&wq_pool_attach_mutex);
}
#ifdef CONFIG_SMP
/*
* CPU hotplug.
*
@ -4600,7 +4649,7 @@ static void unbind_workers(int cpu)
struct worker *worker;
for_each_cpu_worker_pool(pool, cpu) {
mutex_lock(&pool->attach_mutex);
mutex_lock(&wq_pool_attach_mutex);
spin_lock_irq(&pool->lock);
/*
@ -4616,7 +4665,7 @@ static void unbind_workers(int cpu)
pool->flags |= POOL_DISASSOCIATED;
spin_unlock_irq(&pool->lock);
mutex_unlock(&pool->attach_mutex);
mutex_unlock(&wq_pool_attach_mutex);
/*
* Call schedule() so that we cross rq->lock and thus can
@ -4657,7 +4706,7 @@ static void rebind_workers(struct worker_pool *pool)
{
struct worker *worker;
lockdep_assert_held(&pool->attach_mutex);
lockdep_assert_held(&wq_pool_attach_mutex);
/*
* Restore CPU affinity of all workers. As all idle workers should
@ -4727,7 +4776,7 @@ static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
static cpumask_t cpumask;
struct worker *worker;
lockdep_assert_held(&pool->attach_mutex);
lockdep_assert_held(&wq_pool_attach_mutex);
/* is @cpu allowed for @pool? */
if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
@ -4762,14 +4811,14 @@ int workqueue_online_cpu(unsigned int cpu)
mutex_lock(&wq_pool_mutex);
for_each_pool(pool, pi) {
mutex_lock(&pool->attach_mutex);
mutex_lock(&wq_pool_attach_mutex);
if (pool->cpu == cpu)
rebind_workers(pool);
else if (pool->cpu < 0)
restore_unbound_workers_cpumask(pool, cpu);
mutex_unlock(&pool->attach_mutex);
mutex_unlock(&wq_pool_attach_mutex);
}
/* update NUMA affinity of unbound workqueues */
@ -4799,8 +4848,6 @@ int workqueue_offline_cpu(unsigned int cpu)
return 0;
}
#ifdef CONFIG_SMP
struct work_for_cpu {
struct work_struct work;
long (*fn)(void *);

3
kernel/workqueue_internal.h
View File

@ -31,13 +31,12 @@ struct worker {
struct work_struct *current_work; /* L: work being processed */
work_func_t current_func; /* L: current_work's fn */
struct pool_workqueue *current_pwq; /* L: current_work's pwq */
bool desc_valid; /* ->desc is valid */
struct list_head scheduled; /* L: scheduled works */
/* 64 bytes boundary on 64bit, 32 on 32bit */
struct task_struct *task; /* I: worker task */
struct worker_pool *pool; /* I: the associated pool */
struct worker_pool *pool; /* A: the associated pool */
/* L: for rescuers */
struct list_head node; /* A: anchored at pool->workers */
/* A: runs through worker->node */