proc: stop using seq_get_buf in proc_task_name

Use seq_escape_str and seq_printf instead of poking holes into the
seq_file abstraction.

Link: https://lkml.kernel.org/r/20210810151945.1795567-1-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/array.c

@@ -98,27 +98,17 @@
 
 void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
 {
-	char *buf;
-	size_t size;
 	char tcomm[64];
-	int ret;
 
 	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);
-	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_commit(m, ret);
+	if (escape)
+		seq_escape_str(m, tcomm, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
+	else
+		seq_printf(m, "%.64s", tcomm);
 }
 
 /*