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

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

fs/proc/array.c

@@ -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);

fs/proc/base.c

@@ -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);
 

fs/proc/internal.h

@@ -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 *,

include/linux/workqueue.h

@@ -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

kernel/workqueue_internal.h

@@ -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 */