UserSpaceKernel.c

/*
    File:       UserSpaceKernel.c

    Contains:   User space kernel simulation.

    Written by: DTS

    Copyright:  Copyright (c) 2006 by Apple Computer, Inc., All Rights Reserved.

    Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple Computer, Inc.
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                please do not use, install, modify or redistribute this Apple software.

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                to these terms, Apple grants you a personal, non-exclusive license, under Apple's
                copyrights in this original Apple software (the "Apple Software"), to use,
                reproduce, modify and redistribute the Apple Software, with or without
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    Change History (most recent first):

$Log: UserSpaceKernel.c,v $
Revision 1.1  2006/07/27 15:49:30  eskimo1
First checked in.


*/

#include "UserSpaceKernel.h"

#include <CoreFoundation/CoreFoundation.h>

#pragma mark ----- <libkern/OSMalloc.h.h>

struct __OSMallocTag__ {
    int     dummy;
};

static struct __OSMallocTag__ gOneTrueTag;

extern OSMallocTag      OSMalloc_Tagalloc(const char * str, uint32_t flags)
{
    assert(str != NULL);
    assert(flags == OSMT_DEFAULT);
    
    return &gOneTrueTag;
}

extern void             OSMalloc_Tagfree(OSMallocTag tag)
{
    assert(tag == &gOneTrueTag);
}

extern void *           OSMalloc(uint32_t size, OSMallocTag tag)
{
    #pragma unused(tag)
    
    return malloc(size);
}

extern void             OSFree(void * addr, uint32_t size, OSMallocTag tag)
{
    #pragma unused(size)
    #pragma unused(tag)
    
    free(addr);
}

#pragma mark ----- <kern/locks.h.h>

struct __lck_grp__ {
    char name[32];
};

extern  lck_grp_t       *lck_grp_alloc_init(
                                    const char*     grp_name,
                                    lck_grp_attr_t  *attr)
{
    lck_grp_t *     grp;

    assert(grp_name != NULL);
    assert(attr == NULL);
    
    grp = (lck_grp_t *) malloc(sizeof(*grp));
    assert(grp != NULL);
    
    (void) strlcpy(grp->name, grp_name, sizeof(grp->name));
    
    return grp;
}

extern void             lck_grp_free(
                                    lck_grp_t       *grp)
{
    assert(grp != NULL);
    free(grp);
}

struct __lck_mtx__ {
    pthread_mutex_t     mtx;
};

extern lck_mtx_t        *lck_mtx_alloc_init(
                                    lck_grp_t       *grp,
                                    lck_attr_t      *attr)
{
    #pragma unused(grp)
    #pragma unused(attr)
    int         junk;
    lck_mtx_t * result;
    
    result = (lck_mtx_t *) malloc(sizeof(*result));
    if (result != NULL) {
        junk = pthread_mutex_init(&result->mtx, NULL);
        assert(junk == 0);
    }
    return result;
}

extern void             lck_mtx_lock(
                                    lck_mtx_t       *lck)
{
    int     junk;
    
    junk = pthread_mutex_lock(&lck->mtx);
    assert(junk == 0);
}

extern void             lck_mtx_unlock(
                                    lck_mtx_t       *lck)
{
    int     junk;
    
    junk = pthread_mutex_unlock(&lck->mtx);
    assert(junk == 0);
}

extern void             lck_mtx_free(
                                    lck_mtx_t       *lck,
                                    lck_grp_t       *grp)
{
    #pragma unused(grp)
    int     junk;
    
    junk = pthread_mutex_destroy(&lck->mtx);
    assert(junk == 0);
    
    free(lck);
}

extern void             lck_mtx_assert(
                                    lck_mtx_t       *lck,
                                    unsigned int    type)
{
    int     err;
    int     junk;
    
    err = pthread_mutex_trylock(&lck->mtx);
    if (err == 0) {
        assert(type == LCK_MTX_ASSERT_NOTOWNED);
        junk = pthread_mutex_unlock(&lck->mtx);
        assert(junk == 0);
    } else if (err == EBUSY) {
        assert(type == LCK_MTX_ASSERT_OWNED);       // not really a valid test; it could be owned by another thread
    } else {
        assert(false);
    }
}

#pragma mark ----- <sys/vnode.h>

int desiredvnodes = 8000;

struct vnode {
    pthread_mutex_t     mtx;
    int                 getPutRefCount;
    uint32_t            vid;
    void *              fsnode;
};
typedef struct vnode vnode;

static CFMutableArrayRef gVNodes;
    // values are vnode_t

static pthread_mutex_t  gVNodesLock;        // protects gVNodes

static size_t gVNodesMax = 5;

static void InitVNodes(void)
{
    int     junk;
    
    junk = pthread_mutex_init(&gVNodesLock, NULL);
    assert(junk == 0);
    
    gVNodes = CFArrayCreateMutable(NULL, 0, NULL);
    assert(gVNodes != NULL);
}

static ReclaimCallback gReclaimCallback;

extern void SetReclaimCallback(ReclaimCallback callback)
{
    gReclaimCallback = callback;
}

extern errno_t vnode_create(int flavor, size_t size, void *data, vnode_t *vnPtr)
{
    int         err;
    int         junk;
    vnode_t     vn;
    vnode_t     newVN;
    vnode_t     vnToRecycle;
    CFIndex     vnCount;
    CFIndex     vnIndex;
    static pthread_once_t sVNodesControl = PTHREAD_ONCE_INIT;
    
    assert(flavor == VNCREATE_FLAVOR);
    assert(size == VCREATESIZE);
    assert(data != NULL);
    assert(vnPtr != NULL);
    
    // Initialise gVNodes
    
    junk = pthread_once(&sVNodesControl, InitVNodes);
    assert(junk == 0);
    
    newVN = NULL;
    vn = NULL;
    vnToRecycle = NULL;
    do {
        err = EAGAIN;
        
        junk = pthread_mutex_lock(&gVNodesLock);
        assert(junk == 0);
        
        vnCount = CFArrayGetCount(gVNodes);
        if (vnCount  < gVNodesMax) {
            // We can just add a vnode.
            
            if (newVN == NULL) {
                junk = pthread_mutex_unlock(&gVNodesLock);
                assert(junk == 0);

                newVN = (vnode_t) malloc(sizeof(*vn));
                assert(newVN != NULL);
                
                junk = pthread_mutex_init(&newVN->mtx, NULL);
                assert(junk == 0);

                newVN->getPutRefCount = 1;
                newVN->vid = 0;
                newVN->fsnode = ((struct vnode_fsparam *) data)->vnfs_fsnode;

                junk = pthread_mutex_lock(&gVNodesLock);
                assert(junk == 0);
            } else {
                CFArrayAppendValue(gVNodes, newVN);
                vn = newVN;
                newVN = NULL;
                err = 0;
            }
        } else {
            // We must recycle a vnode.
            
            for (vnIndex = 0; vnIndex < vnCount; vnIndex++) {
                vnode_t     thisVN;

                thisVN = (vnode_t) CFArrayGetValueAtIndex(gVNodes, vnIndex);
                if (thisVN->getPutRefCount == 0) {
                    vnToRecycle = thisVN;
                    err = 0;

                    // Move the vnode we're recycling (well, the one that 
                    // we're /planning/ to recycle) to the end of the list, 
                    // so that it doesn't get immediately recycled again.
                    
                    CFArrayRemoveValueAtIndex(gVNodes, vnIndex);
                    CFArrayAppendValue(gVNodes, vnToRecycle);
                    break;
                }
            }
        }

        junk = pthread_mutex_unlock(&gVNodesLock);
        assert(junk == 0);

        if ( (err == 0) && (vnToRecycle != NULL) ) {
            assert(vn == NULL);
            
            junk = pthread_mutex_lock(&vnToRecycle->mtx);
            assert(junk == 0);
            
            if (vnToRecycle->getPutRefCount == 0) {
                // Stop anyone else messing with it

                vnToRecycle->getPutRefCount = 1;
                
                // Detach it from the file system.  This is super bogus because 
                // we're doing this with the vnode lock held.  If the client code 
                // called back into us to do anything interesting, they'd deadlock. 
                // However, that currently doesn't happen and, besides, dropping 
                // the lock is /hard/ (just look at the VFS implementation :-).

                gReclaimCallback(vnToRecycle);

                // invalidate any cached references

                vnToRecycle->vid += 1;

                vnToRecycle->fsnode = ((struct vnode_fsparam *) data)->vnfs_fsnode;

                junk = pthread_mutex_unlock(&vnToRecycle->mtx);
                assert(junk == 0);

                vn = vnToRecycle;
                err = 0;
            } else {
                junk = pthread_mutex_unlock(&vnToRecycle->mtx);
                assert(junk == 0);

                // Someone started using the vnode between our test (inside the 
                // for loop, above) and us locking the vnode.  We just start again 
                // from the beginning.
                
                vnToRecycle = NULL;
                err = EAGAIN;
            }
        }
    } while (err == EAGAIN);

    assert(err == 0);
    
    // Didn't use our new vnode, so junk it.
    
    if (newVN != NULL) {
        junk = pthread_mutex_destroy(&newVN->mtx);
        assert(junk == 0);
        
        free(newVN);
    }
    
    *vnPtr = vn;

    return 0;
}

extern void DisposeAllVNodes(void)
    // This doesn't even pretend to be thread safe.  Making it thread safe would 
    // be quite complicated, and there's no real reason to do so.
{
    int         junk;
    CFIndex     vnCount;
    vnode_t     vn;
    
    if (gVNodes != NULL) {
        do {
            vnCount = CFArrayGetCount(gVNodes);
            if (vnCount != 0) {
                vn = (vnode_t) CFArrayGetValueAtIndex(gVNodes, vnCount - 1);
                assert(vn->getPutRefCount == 0);
                
                CFArrayRemoveValueAtIndex(gVNodes, vnCount - 1);
                
                gReclaimCallback(vn);
                
                junk = pthread_mutex_destroy(&vn->mtx);
                assert(junk == 0);
                
                free(vn);
            }
        } while (vnCount != 0);
    }
}

extern uint32_t vnode_vid(vnode_t vn)
{
    return vn->vid;
}

extern int vnode_getwithvid(vnode_t vn, int vid)
{
    int         err;
    int         junk;
    
    assert(vn != NULL);
    
    junk = pthread_mutex_lock(&vn->mtx);
    assert(junk == 0);
    
    err = 0;
    if (vn->vid != vid) {
        err = ENOENT;
    } else {
        vn->getPutRefCount += 1;
    }
    
    junk = pthread_mutex_unlock(&vn->mtx);
    assert(junk == 0);
    
    return err;
}

extern int vnode_put(vnode_t vn)
{
    int         junk;
    
    assert(vn != NULL);
    
    junk = pthread_mutex_lock(&vn->mtx);
    assert(junk == 0);

    vn->getPutRefCount -= 1;
    assert(vn->getPutRefCount >= 0);
    
    if (vn->getPutRefCount == 0) {
        // *** This is where we'd tell the file system that the vnode is inactive, 
        // but we currently don't need that facility.
    }
    
    junk = pthread_mutex_unlock(&vn->mtx);
    assert(junk == 0);
    
    return 0;
}

extern int vnode_addfsref(vnode_t vn)
{
    assert(vn != NULL);
    return 0;
}

extern int vnode_removefsref(vnode_t vn)
{
    assert(vn != NULL);
    return 0;
}

extern void * vnode_fsnode(vnode_t vn)
{
    return vn->fsnode;
}

extern void vnode_clearfsnode(vnode_t vn)
{
    assert(vn != NULL);
    vn->fsnode = NULL;
}

#pragma mark ----- <sys/systm.h>

void    *hashinit(int count, int type, u_long *hashmask)
{
    u_long                          hashsize;
    LIST_HEAD(generic, generic) *   hashtbl;
    int                             i;
    
    assert(count >= 0);
    assert(type == M_TEMP);
    assert(hashmask != NULL);
    
    for (hashsize = 1; hashsize <= count; hashsize <<= 1)
        continue;
    hashsize >>= 1;
    hashtbl = malloc(hashsize * sizeof(*hashtbl));
    if (hashtbl != NULL) {
        for (i = 0; i < hashsize; i++) {
            LIST_INIT(&hashtbl[i]);
        }
        *hashmask = hashsize - 1;
    }
    return hashtbl;
}

#pragma mark ----- <sys/malloc.h>

extern void FREE(void *addr, int type)
{
    assert(type == M_TEMP);
    
    free(addr);
}

#pragma mark ----- <sys/proc.h>

static CFMutableDictionaryRef gChannelToCond;
    // keys are wait channels (void *)
    // values are pthread_cond_t *

static pthread_mutex_t  gChannelToCondLock;

static void InitChannelToCond(void)
{
    int     junk;
    
    junk = pthread_mutex_init(&gChannelToCondLock, NULL);
    assert(junk == 0);
    
    gChannelToCond = CFDictionaryCreateMutable(NULL, 0, NULL, NULL);
    assert(gChannelToCond != NULL);
}

static pthread_cond_t * ChannelToCond(void *chan)
{
    int                 err;
    int                 junk;
    pthread_cond_t *    cond;
    pthread_cond_t *    newCond;
    static pthread_once_t sChannelToCondControl = PTHREAD_ONCE_INIT;

    newCond = NULL;
    
    // Lazy init of gChannelToCond.
    
    junk = pthread_once(&sChannelToCondControl, InitChannelToCond);
    assert(junk == 0);
    
    // Look up the channel to find or create the associated conditional variable.
    
    junk = pthread_mutex_lock(&gChannelToCondLock);
    assert(junk == 0);
    
    do {
        err = 0;

        cond = (pthread_cond_t *) CFDictionaryGetValue(gChannelToCond, chan);
        if (cond == NULL) {
            if (newCond == NULL) {
                junk = pthread_mutex_unlock(&gChannelToCondLock);
                assert(junk == 0);

                newCond = (pthread_cond_t *) malloc(sizeof(*newCond));
                assert(newCond != NULL);
                
                junk = pthread_cond_init(newCond, NULL);
                assert(junk == 0);
                
                err = EAGAIN;

                junk = pthread_mutex_lock(&gChannelToCondLock);
                assert(junk == 0);
            } else {
                CFDictionaryAddValue(gChannelToCond, chan, newCond);
                cond = newCond;
                newCond = NULL;
            }
        }
    } while (err == EAGAIN);
    
    junk = pthread_mutex_unlock(&gChannelToCondLock);
    assert(junk == 0);
    
    // If we created newCond but didn't use it, free it now.
    
    if (newCond != NULL) {
        junk = pthread_cond_destroy(newCond);
        assert(junk == 0);
        
        free(newCond);
    }
    
    return cond;
}

extern int  msleep(void *chan, lck_mtx_t *mtx, int pri, const char *wmesg, struct timespec * ts)
{
    #pragma unused(pri)
    #pragma unused(wmesg)
    int                 junk;
    pthread_cond_t *    cond;

    assert(mtx != NULL);
    assert(pri == PINOD);
    assert(ts == NULL);

    cond = ChannelToCond(chan);
    assert(cond != NULL);
    
    junk = pthread_cond_wait(cond, &mtx->mtx);
    assert(junk == 0);
    
    return 0;
}

extern void wakeup(void *chan)
{
    int                 junk;
    pthread_cond_t *    cond;
    
    cond = ChannelToCond(chan);
    assert(cond != NULL);
    
    junk = pthread_cond_broadcast(cond);
    assert(junk == 0);
}