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#include <linux/sched.h>
#include <litmus/litmus.h>
#include <litmus/dgl.h>
#include <litmus/sched_trace.h>
/* Word, bit -> resource id */
#define ri(w, b) (w * MASK_SIZE + b)
/* For loop, where @i iterates over each set bit in @bit_arr */
#define for_each_resource(bit_arr, w, b, i) \
for(w = 0; w < MASK_WORDS; ++w) \
for(b = find_first_bit(&bit_arr[w],MASK_SIZE), i = ri(w, b); \
b < MASK_SIZE; \
b = find_next_bit(&bit_arr[w],MASK_SIZE,b+1), i = ri(w, b))
/* Return resource id in dgl @d for resource @r */
#define resource_id(d, r) ((((void*)r) - (void*)(&(d)->resources))/ sizeof(*r))
/* Return request group of req @r for resource @i */
#define req_group(r, i) (container_of(((void*)r) - sizeof(*r)*(i), \
struct dgl_group_req, requests))
/* Resource id -> word, bit */
static inline void mask_idx(int resource, int *word, int *bit)
{
*word = resource / MASK_SIZE;
*bit = resource % MASK_SIZE;
}
void dgl_init(struct dgl *dgl)
{
int i;
struct dgl_resource *resource;
for (i = 0; i < NR_CPUS; i++)
dgl->acquired[i] = NULL;
for (i = 0; i < NUM_RESOURCES; i++) {
resource = &dgl->resources[i];
INIT_LIST_HEAD(&resource->waiting);
resource->free_replicas = NUM_REPLICAS;
}
}
void dgl_group_req_init(struct dgl_group_req *greq)
{
int i;
greq->cpu = NO_CPU;
for (i = 0; i < MASK_WORDS; i++) {
greq->requested[i] = 0;
greq->waiting[i] = 0;
}
}
/**
* set_req - create request for @replicas of @resource.
*/
void set_req(struct dgl_group_req *greq, int resource, int replicas)
{
int word, bit;
struct dgl_req *req;
BUG_ON(replicas > NUM_REPLICAS);
mask_idx(resource, &word, &bit);
TRACE("0x%p will request resource %d, word %d, bit %d\n",
greq, resource, word, bit);
__set_bit(bit, &greq->requested[word]);
req = &greq->requests[resource];
INIT_LIST_HEAD(&req->list);
req->replicas = replicas;
}
/*
* Attempt to fulfill request @req for @resource.
* Return 1 if successful. If the matching group request has acquired all of
* its needed resources, this will then set that req as dgl->acquired[cpu].
*/
static unsigned long try_acquire(struct dgl *dgl, struct dgl_resource *resource,
struct dgl_req *req)
{
int word, bit, rid;
unsigned long waiting;
struct dgl_group_req *greq;
if (resource->free_replicas < req->replicas) {
TRACE("0x%p cannot acquire %d replicas, only %d free\n",
greq, req->replicas, resource->free_replicas);
return 0;
}
resource->free_replicas -= req->replicas;
rid = resource_id(dgl, resource);
greq = req_group(req, rid);
mask_idx(rid, &word, &bit);
TRACE("0x%p acquired rid %d, word %d, bit %d\n",
greq, rid, word, bit);
clear_bit(bit, &greq->waiting[word]);
waiting = 0;
for (word = 0; word < MASK_WORDS; word++) {
waiting |= greq->waiting[word];
if (waiting)
break;
}
if (!waiting) {
TRACE("0x%p acquired all resources\n", greq);
BUG_ON(dgl->acquired[greq->cpu]);
dgl->acquired[greq->cpu] = greq;
litmus_reschedule(greq->cpu);
}
return 1;
}
/**
* add_group_req - initiate group request.
*/
void add_group_req(struct dgl *dgl, struct dgl_group_req *greq, int cpu)
{
int b, w, i, succ, all_succ = 1;
struct dgl_req *req;
struct dgl_resource *resource;
greq->cpu = cpu;
TRACE("0x%p group request added for CPU %d\n", greq, cpu);
BUG_ON(dgl->acquired[cpu] == greq);
for_each_resource(greq->requested, w, b, i) {
__set_bit(b, &greq->waiting[w]);
}
for_each_resource(greq->requested, w, b, i) {
req = &greq->requests[i];
resource = &dgl->resources[i];
succ = try_acquire(dgl, resource, req);
all_succ &= succ;
if (!succ) {
TRACE("0x%p waiting on resource %d\n", greq, i);
list_add_tail(&req->list, &resource->waiting);
}
}
}
/**
* remove_group_req - abandon group request.
*
* This will also progress the waiting queues of resources acquired by @greq.
*/
void remove_group_req(struct dgl *dgl, struct dgl_group_req *greq)
{
int b, w, i;
struct dgl_req *req, *next;
struct dgl_resource *resource;
TRACE("0x%p removing group request for CPU %d\n", greq, greq->cpu);
if (dgl->acquired[greq->cpu] == greq) {
TRACE("0x%p no longer acquired on CPU %d\n", greq, greq->cpu);
dgl->acquired[greq->cpu] = NULL;
}
for_each_resource(greq->requested, w, b, i) {
req = &greq->requests[i];
resource = &dgl->resources[i];
if (!list_empty(&req->list)) {
/* Waiting on resource */
clear_bit(b, &greq->waiting[w]);
list_del_init(&req->list);
TRACE("0x%p quit waiting for resource %d\n", greq, i);
} else {
/* Have resource */
resource->free_replicas += req->replicas;
TRACE("0x%p releasing resource %d\n", greq, i);
if (!list_empty(&resource->waiting)) {
/* Give it to the next guy */
next = list_first_entry(&resource->waiting,
struct dgl_req,
list);
if (try_acquire(dgl, resource, next))
list_del_init(&next->list);
}
}
}
}
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