patch-2.1.19 linux/arch/sparc64/mm/asyncd.c

• Lines: 273
• Date: Mon Dec 30 11:59:59 1996
• Orig file: v2.1.18/linux/arch/sparc64/mm/asyncd.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.18/linux/arch/sparc64/mm/asyncd.c linux/arch/sparc64/mm/asyncd.c
@@ -0,0 +1,272 @@
+/*  $Id: asyncd.c,v 1.1 1996/12/26 10:24:24 davem Exp $
+ *  The asyncd kernel daemon. This handles paging on behalf of 
+ *  processes that receive page faults due to remote (async) memory
+ *  accesses. 
+ *
+ *  Idea and skeleton code courtesy of David Miller (bless his cotton socks)
+ *
+ *  Implemented by tridge
+ */
+
+#include <linux/mm.h>
+#include <linux/malloc.h>
+#include <linux/sched.h>
+#include <linux/head.h>
+#include <linux/kernel.h>
+#include <linux/kernel_stat.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/stat.h>
+#include <linux/swap.h>
+#include <linux/fs.h>
+#include <linux/config.h>
+#include <linux/interrupt.h>
+
+#include <asm/dma.h>
+#include <asm/system.h> /* for cli()/sti() */
+#include <asm/segment.h> /* for memcpy_to/fromfs */
+#include <asm/bitops.h>
+#include <asm/pgtable.h>
+
+#define DEBUG 0
+
+#define WRITE_LIMIT 100
+#define LOOP_LIMIT 200
+
+static struct {
+	int faults, read, write, success, failure, errors;
+} stats;
+
+/* 
+ * The wait queue for waking up the async daemon:
+ */
+static struct wait_queue * asyncd_wait = NULL;
+
+struct async_job {
+	volatile struct async_job *next;
+	int taskid;
+	struct mm_struct *mm;
+	unsigned long address;
+	int write;
+	void (*callback)(int,unsigned long,int,int);
+};
+
+static volatile struct async_job *async_queue = NULL;
+static volatile struct async_job *async_queue_end = NULL;
+
+static void add_to_async_queue(int taskid,
+			       struct mm_struct *mm,
+			       unsigned long address,
+			       int write,
+			       void (*callback)(int,unsigned long,int,int))
+{
+	struct async_job *a = kmalloc(sizeof(*a),GFP_ATOMIC);
+
+	if (!a) {
+		printk("ERROR: out of memory in asyncd\n");
+		a->callback(taskid,address,write,1);
+		return;
+	}
+
+	if (write)
+		stats.write++;
+	else
+		stats.read++;
+
+	a->next = NULL;
+	a->taskid = taskid;
+	a->mm = mm;
+	a->address = address;
+	a->write = write;
+	a->callback = callback;
+
+	if (!async_queue) {
+		async_queue = a;
+	} else {
+		async_queue_end->next = a;
+	}
+	async_queue_end = a;
+}
+
+
+void async_fault(unsigned long address, int write, int taskid,
+		 void (*callback)(int,unsigned long,int,int))
+{
+	struct task_struct *tsk = task[taskid];
+	struct mm_struct *mm = tsk->mm;
+
+	stats.faults++;
+
+#if 0
+	printk("paging in %x for task=%d\n",address,taskid);
+#endif
+
+	add_to_async_queue(taskid, mm, address, write, callback);
+	wake_up(&asyncd_wait);  
+	mark_bh(TQUEUE_BH);
+}
+
+static int fault_in_page(int taskid,
+			 struct vm_area_struct *vma,
+			 unsigned address,int write)
+{
+	static unsigned last_address;
+	static int last_task, loop_counter;
+	struct task_struct *tsk = task[taskid];
+	pgd_t *pgd;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	if (!tsk || !tsk->mm)
+		return 1;
+
+	if (!vma || (write && !(vma->vm_flags & VM_WRITE)))
+	  goto bad_area;
+	if (vma->vm_start > address)
+	  goto bad_area;
+
+	if (address == last_address && taskid == last_task) {
+		loop_counter++;
+	} else {
+		loop_counter = 0;
+		last_address = address; 
+		last_task = taskid;
+	}
+
+	if (loop_counter == WRITE_LIMIT && !write) {
+		printk("MSC bug? setting write request\n");
+		stats.errors++;
+		write = 1;
+	}
+
+	if (loop_counter == LOOP_LIMIT) {
+		printk("MSC bug? failing request\n");
+		stats.errors++;
+		return 1;
+	}
+
+	pgd = pgd_offset(vma->vm_mm, address);
+	pmd = pmd_alloc(pgd,address);
+	if(!pmd)
+		goto no_memory;
+	pte = pte_alloc(pmd, address);
+	if(!pte)
+		goto no_memory;
+	if(!pte_present(*pte)) {
+		do_no_page(tsk, vma, address, write);
+		goto finish_up;
+	}
+	set_pte(pte, pte_mkyoung(*pte));
+	flush_tlb_page(vma, address);
+	if(!write)
+		goto finish_up;
+	if(pte_write(*pte)) {
+		set_pte(pte, pte_mkdirty(*pte));
+		flush_tlb_page(vma, address);
+		goto finish_up;
+	}
+	do_wp_page(tsk, vma, address, write);
+
+	/* Fall through for do_wp_page */
+finish_up:
+	stats.success++;
+	update_mmu_cache(vma, address, *pte);
+	return 0;
+
+no_memory:
+	stats.failure++;
+	oom(tsk);
+	return 1;
+	
+bad_area:	  
+	stats.failure++;
+	tsk->tss.sig_address = address;
+	tsk->tss.sig_desc = SUBSIG_NOMAPPING;
+	send_sig(SIGSEGV, tsk, 1);
+	return 1;
+}
+
+
+/* Note the semaphore operations must be done here, and _not_
+ * in async_fault().
+ */
+static void run_async_queue(void)
+{
+	int ret;
+	unsigned flags;
+
+	while (async_queue) {
+		volatile struct async_job *a;
+		struct mm_struct *mm;
+		struct vm_area_struct *vma;
+
+		save_flags(flags); cli();
+		a = async_queue;
+		async_queue = async_queue->next;
+		restore_flags(flags);
+
+		mm = a->mm;
+
+		down(&mm->mmap_sem);
+		vma = find_vma(mm, a->address);
+		ret = fault_in_page(a->taskid,vma,a->address,a->write);
+#if DEBUG
+		printk("fault_in_page(task=%d addr=%x write=%d) = %d\n",
+		       a->taskid,a->address,a->write,ret);
+#endif
+		a->callback(a->taskid,a->address,a->write,ret);
+		up(&mm->mmap_sem);
+		kfree_s((void *)a,sizeof(*a));
+	}
+}
+
+
+#if CONFIG_AP1000
+static void asyncd_info(void)
+{
+	printk("CID(%d) faults: total=%d  read=%d  write=%d  success=%d fail=%d err=%d\n",
+	       mpp_cid(),stats.faults, stats.read, stats.write, stats.success,
+	       stats.failure, stats.errors);
+}
+#endif
+
+
+/*
+ * The background async daemon.
+ * Started as a kernel thread from the init process.
+ */
+int asyncd(void *unused)
+{
+	current->session = 1;
+	current->pgrp = 1;
+	sprintf(current->comm, "asyncd");
+	current->blocked = ~0UL; /* block all signals */
+  
+	/* Give asyncd a realtime priority. */
+	current->policy = SCHED_FIFO;
+	current->priority = 32;  /* Fixme --- we need to standardise our
+				    namings for POSIX.4 realtime scheduling
+				    priorities.  */
+  
+	printk("Started asyncd\n");
+
+#if CONFIG_AP1000
+	bif_add_debug_key('a',asyncd_info,"stats on asyncd");
+#endif
+
+	while (1) {
+		unsigned flags;
+
+		save_flags(flags); cli();
+
+		while (!async_queue) {
+			current->signal = 0;
+			interruptible_sleep_on(&asyncd_wait);
+		}
+
+		restore_flags(flags);
+
+		run_async_queue();
+	}
+}
+