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o Control access to the vm_page_buckets with a mutex.

Browse Source 
o Fix some style(9) bugs.
This commit is contained in:
Alan Cox 2002-04-26 22:44:15 +00:00
parent 8373917257
commit cbd53e95fe
1 changed files with 17 additions and 33 deletions
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50
sys/vm/vm_page.c
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@ -125,11 +125,10 @@
* Associated with page of user-allocatable memory is a
* page structure.
*/
static struct mtx vm_page_buckets_mtx;
static struct vm_page **vm_page_buckets; /* Array of buckets */
static int vm_page_bucket_count; /* How big is array? */
static int vm_page_hash_mask; /* Mask for hash function */
static volatile int vm_page_bucket_generation;
static struct mtx vm_buckets_mtx[BUCKET_HASH_SIZE];
vm_page_t vm_page_array = 0;
int vm_page_array_size = 0;
@ -254,15 +253,13 @@ vm_page_startup(vm_offset_t starta, vm_offset_t enda, vm_offset_t vaddr)
VM_PROT_READ | VM_PROT_WRITE);
bzero((caddr_t) mapped, end - new_end);
mtx_init(&vm_page_buckets_mtx, "vm page buckets mutex", NULL, MTX_DEF);
vm_page_buckets = (struct vm_page **)mapped;
bucket = vm_page_buckets;
for (i = 0; i < vm_page_bucket_count; i++) {
*bucket = NULL;
bucket++;
}
for (i = 0; i < BUCKET_HASH_SIZE; ++i)
mtx_init(&vm_buckets_mtx[i], "vm buckets hash mutexes", NULL,
MTX_DEF);
/*
* Compute the number of pages of memory that will be available for
@ -590,9 +587,10 @@ vm_page_insert(vm_page_t m, vm_object_t object, vm_pindex_t pindex)
* Insert it into the object_object/offset hash table
*/
bucket = &vm_page_buckets[vm_page_hash(object, pindex)];
mtx_lock(&vm_page_buckets_mtx);
m->hnext = *bucket;
*bucket = m;
vm_page_bucket_generation++;
mtx_unlock(&vm_page_buckets_mtx);
/*
* Now link into the object's list of backed pages.
@ -629,6 +627,7 @@ void
vm_page_remove(vm_page_t m)
{
vm_object_t object;
vm_page_t *bucket;
GIANT_REQUIRED;
@ -649,23 +648,17 @@ vm_page_remove(vm_page_t m)
/*
* Remove from the object_object/offset hash table. The object
* must be on the hash queue, we will panic if it isn't
*
* Note: we must NULL-out m->hnext to prevent loops in detached
* buffers with vm_page_lookup().
*/
{
struct vm_page **bucket;
bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)];
while (*bucket != m) {
if (*bucket == NULL)
panic("vm_page_remove(): page not found in hash");
bucket = &(*bucket)->hnext;
}
*bucket = m->hnext;
m->hnext = NULL;
vm_page_bucket_generation++;
bucket = &vm_page_buckets[vm_page_hash(m->object, m->pindex)];
mtx_lock(&vm_page_buckets_mtx);
while (*bucket != m) {
if (*bucket == NULL)
panic("vm_page_remove(): page not found in hash");
bucket = &(*bucket)->hnext;
}
*bucket = m->hnext;
m->hnext = NULL;
mtx_unlock(&vm_page_buckets_mtx);
/*
* Now remove from the object's list of backed pages.
@ -687,11 +680,6 @@ vm_page_remove(vm_page_t m)
* Returns the page associated with the object/offset
* pair specified; if none is found, NULL is returned.
*
* NOTE: the code below does not lock. It will operate properly if
* an interrupt makes a change, but the generation algorithm will not
* operate properly in an SMP environment where both cpu's are able to run
* kernel code simultaneously.
*
* The object must be locked. No side effects.
* This routine may not block.
* This is a critical path routine
@ -701,23 +689,19 @@ vm_page_lookup(vm_object_t object, vm_pindex_t pindex)
{
vm_page_t m;
struct vm_page **bucket;
int generation;
/*
* Search the hash table for this object/offset pair
*/
retry:
generation = vm_page_bucket_generation;
bucket = &vm_page_buckets[vm_page_hash(object, pindex)];
mtx_lock(&vm_page_buckets_mtx);
for (m = *bucket; m != NULL; m = m->hnext) {
if ((m->object == object) && (m->pindex == pindex)) {
if (vm_page_bucket_generation != generation)
goto retry;
mtx_unlock(&vm_page_buckets_mtx);
return (m);
}
}
if (vm_page_bucket_generation != generation)
goto retry;
mtx_unlock(&vm_page_buckets_mtx);
return (NULL);
}