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Memory ordering and usage of ASM cmpxchg() instead of compiler atomic intrinsics

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Change-Id: I4dadebc32721744dad982f3fc5b3eea7ab7ca745
This commit is contained in:
Balazs Gerofi
2019-08-13 15:17:07 +09:00
committed by Masamichi Takagi
parent 7aa2d64294
commit c3c57940ba
4 changed files with 30 additions and 26 deletions
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4
executer/kernel/mcctrl/control.c
View File

@ -1452,7 +1452,7 @@ retry_alloc:
__FUNCTION__, task_pid_vnr(current), packet->ref); __FUNCTION__, task_pid_vnr(current), packet->ref);
mb(); mb();
if (!packet->req.valid) { if (!smp_load_acquire(&packet->req.valid)) {
printk("%s: ERROR: stray wakeup pid: %d, tid: %d: SC %lu\n", printk("%s: ERROR: stray wakeup pid: %d, tid: %d: SC %lu\n",
__FUNCTION__, __FUNCTION__,
task_tgid_vnr(current), task_tgid_vnr(current),
@ -1462,7 +1462,7 @@ retry_alloc:
goto retry; goto retry;
} }
packet->req.valid = 0; /* ack */ smp_store_release(&packet->req.valid, 0); /* ack */
dprintk("%s: system call: %d, args[0]: %lu, args[1]: %lu, args[2]: %lu, " dprintk("%s: system call: %d, args[0]: %lu, args[1]: %lu, args[2]: %lu, "
"args[3]: %lu, args[4]: %lu, args[5]: %lu\n", "args[3]: %lu, args[4]: %lu, args[5]: %lu\n",
__FUNCTION__, __FUNCTION__,

12
executer/kernel/mcctrl/syscall.c
View File

@ -228,9 +228,10 @@ static int __notify_syscall_requester(ihk_os_t os, struct ikc_scd_packet *packet
c = (usrdata->channels + packet->ref)->c; c = (usrdata->channels + packet->ref)->c;
/* If spinning, no need for IKC message */ /* If spinning, no need for IKC message */
if (__sync_bool_compare_and_swap(&res->req_thread_status, if (cmpxchg(&res->req_thread_status,
IHK_SCD_REQ_THREAD_SPINNING, IHK_SCD_REQ_THREAD_SPINNING,
IHK_SCD_REQ_THREAD_TO_BE_WOKEN)) { IHK_SCD_REQ_THREAD_TO_BE_WOKEN) ==
IHK_SCD_REQ_THREAD_SPINNING) {
dprintk("%s: no need to send IKC message for PID %d\n", dprintk("%s: no need to send IKC message for PID %d\n",
__FUNCTION__, packet->pid); __FUNCTION__, packet->pid);
return ret; return ret;
@ -239,7 +240,7 @@ static int __notify_syscall_requester(ihk_os_t os, struct ikc_scd_packet *packet
/* Wait until the status goes back to IHK_SCD_REQ_THREAD_SPINNING or /* Wait until the status goes back to IHK_SCD_REQ_THREAD_SPINNING or
IHK_SCD_REQ_THREAD_DESCHEDULED because two wake-up attempts are competing. IHK_SCD_REQ_THREAD_DESCHEDULED because two wake-up attempts are competing.
Note that mcexec_terminate_thread() and returning EINTR would compete. */ Note that mcexec_terminate_thread() and returning EINTR would compete. */
if (res->req_thread_status == IHK_SCD_REQ_THREAD_TO_BE_WOKEN) { if (smp_load_acquire(&res->req_thread_status) == IHK_SCD_REQ_THREAD_TO_BE_WOKEN) {
printk("%s: INFO: someone else is waking up the McKernel thread, " printk("%s: INFO: someone else is waking up the McKernel thread, "
"pid: %d, req status: %lu, syscall nr: %lu\n", "pid: %d, req status: %lu, syscall nr: %lu\n",
__FUNCTION__, packet->pid, __FUNCTION__, packet->pid,
@ -247,9 +248,10 @@ static int __notify_syscall_requester(ihk_os_t os, struct ikc_scd_packet *packet
} }
/* The thread is not spinning any more, make sure it's descheduled */ /* The thread is not spinning any more, make sure it's descheduled */
if (!__sync_bool_compare_and_swap(&res->req_thread_status, if (cmpxchg(&res->req_thread_status,
IHK_SCD_REQ_THREAD_DESCHEDULED, IHK_SCD_REQ_THREAD_DESCHEDULED,
IHK_SCD_REQ_THREAD_TO_BE_WOKEN)) { IHK_SCD_REQ_THREAD_TO_BE_WOKEN) !=
IHK_SCD_REQ_THREAD_DESCHEDULED) {
printk("%s: WARNING: inconsistent requester status, " printk("%s: WARNING: inconsistent requester status, "
"pid: %d, req status: %lu, syscall nr: %lu\n", "pid: %d, req status: %lu, syscall nr: %lu\n",
__FUNCTION__, packet->pid, __FUNCTION__, packet->pid,

3
kernel/fileobj.c
View File

@ -587,8 +587,7 @@ static int fileobj_get_page(struct memobj *memobj, off_t off,
/* Update the array but see if someone did it already and use /* Update the array but see if someone did it already and use
* that if so */ * that if so */
if (!__sync_bool_compare_and_swap(&memobj->pages[page_ind], if (cmpxchg(&memobj->pages[page_ind], NULL, virt) != NULL) {
NULL, virt)) {
ihk_mc_free_pages_user(virt, 1); ihk_mc_free_pages_user(virt, 1);
} }
else { else {

33
kernel/syscall.c
View File

@ -159,7 +159,7 @@ static void send_syscall(struct syscall_request *req, int cpu,
memcpy(&packet.req, req, sizeof(*req)); memcpy(&packet.req, req, sizeof(*req));
barrier(); barrier();
packet.req.valid = 1; smp_store_release(&packet.req.valid, 1);
#ifdef SYSCALL_BY_IKC #ifdef SYSCALL_BY_IKC
packet.msg = SCD_MSG_SYSCALL_ONESIDE; packet.msg = SCD_MSG_SYSCALL_ONESIDE;
@ -234,8 +234,8 @@ long do_syscall(struct syscall_request *req, int cpu)
#define STATUS_COMPLETED 1 #define STATUS_COMPLETED 1
#define STATUS_PAGE_FAULT 3 #define STATUS_PAGE_FAULT 3
#define STATUS_SYSCALL 4 #define STATUS_SYSCALL 4
while (res.status != STATUS_COMPLETED) { while (smp_load_acquire(&res.status) != STATUS_COMPLETED) {
while (res.status == STATUS_IN_PROGRESS) { while (smp_load_acquire(&res.status) == STATUS_IN_PROGRESS) {
struct cpu_local_var *v; struct cpu_local_var *v;
int do_schedule = 0; int do_schedule = 0;
long runq_irqstate; long runq_irqstate;
@ -273,10 +273,12 @@ long do_syscall(struct syscall_request *req, int cpu)
flags = cpu_disable_interrupt_save(); flags = cpu_disable_interrupt_save();
/* Try to sleep until notified */ /* Try to sleep until notified */
if (res.req_thread_status == IHK_SCD_REQ_THREAD_DESCHEDULED || if (smp_load_acquire(&res.req_thread_status) ==
__sync_bool_compare_and_swap(&res.req_thread_status, IHK_SCD_REQ_THREAD_DESCHEDULED ||
(cmpxchg(&res.req_thread_status,
IHK_SCD_REQ_THREAD_SPINNING, IHK_SCD_REQ_THREAD_SPINNING,
IHK_SCD_REQ_THREAD_DESCHEDULED)) { IHK_SCD_REQ_THREAD_DESCHEDULED) ==
IHK_SCD_REQ_THREAD_SPINNING)) {
dkprintf("%s: tid %d waiting for syscall reply...\n", dkprintf("%s: tid %d waiting for syscall reply...\n",
__FUNCTION__, thread->tid); __FUNCTION__, thread->tid);
waitq_init(&thread->scd_wq); waitq_init(&thread->scd_wq);
@ -300,7 +302,7 @@ long do_syscall(struct syscall_request *req, int cpu)
cpu_restore_interrupt(flags); cpu_restore_interrupt(flags);
} }
if (res.status == STATUS_SYSCALL) { if (smp_load_acquire(&res.status) == STATUS_SYSCALL) {
struct syscall_request *requestp; struct syscall_request *requestp;
struct syscall_request request; struct syscall_request request;
int num; int num;
@ -1125,8 +1127,8 @@ void terminate_mcexec(int rc, int sig)
if ((old_exit_status = proc->group_exit_status) & 0x0000000100000000L) if ((old_exit_status = proc->group_exit_status) & 0x0000000100000000L)
return; return;
exit_status = 0x0000000100000000L | ((rc & 0x00ff) << 8) | (sig & 0xff); exit_status = 0x0000000100000000L | ((rc & 0x00ff) << 8) | (sig & 0xff);
if (!__sync_bool_compare_and_swap(&proc->group_exit_status, if (cmpxchg(&proc->group_exit_status,
old_exit_status, exit_status)) old_exit_status, exit_status) != old_exit_status)
return; return;
if (!proc->nohost) { if (!proc->nohost) {
request.number = __NR_exit_group; request.number = __NR_exit_group;
@ -1979,8 +1981,8 @@ do_mmap(const uintptr_t addr0, const size_t len0, const int prot,
populate_len = memobj ? min(len, memobj->size) : len; populate_len = memobj ? min(len, memobj->size) : len;
if (!(flags & MAP_ANONYMOUS)) { if (!(flags & MAP_ANONYMOUS)) {
if (atomic_cmpxchg4(&memobj->status, MEMOBJ_TO_BE_PREFETCHED, if (cmpxchg(&memobj->status, MEMOBJ_TO_BE_PREFETCHED,
MEMOBJ_READY)) { MEMOBJ_READY) == MEMOBJ_TO_BE_PREFETCHED) {
populated_mapping = 1; populated_mapping = 1;
} }
@ -2884,8 +2886,8 @@ unsigned long do_fork(int clone_flags, unsigned long newsp,
retry_tid: retry_tid:
for (i = 0; i < newproc->nr_tids; ++i) { for (i = 0; i < newproc->nr_tids; ++i) {
if (!newproc->tids[i].thread) { if (!newproc->tids[i].thread) {
if (!__sync_bool_compare_and_swap( if (cmpxchg(&newproc->tids[i].thread,
&newproc->tids[i].thread, NULL, new)) { NULL, new) != NULL) {
goto retry_tid; goto retry_tid;
} }
new->tid = newproc->tids[i].tid; new->tid = newproc->tids[i].tid;
@ -2988,7 +2990,8 @@ retry_tid:
new->status = PS_RUNNING; new->status = PS_RUNNING;
/* Only the first do_fork() call creates a thread on a Linux CPU */ /* Only the first do_fork() call creates a thread on a Linux CPU */
if (__sync_bool_compare_and_swap(&old->mod_clone, SPAWN_TO_REMOTE, SPAWN_TO_LOCAL)) { if (cmpxchg(&old->mod_clone, SPAWN_TO_REMOTE, SPAWN_TO_LOCAL) ==
SPAWN_TO_REMOTE) {
new->mod_clone = SPAWNING_TO_REMOTE; new->mod_clone = SPAWNING_TO_REMOTE;
if (old->mod_clone_arg) { if (old->mod_clone_arg) {
new->mod_clone_arg = kmalloc(sizeof(struct uti_attr), new->mod_clone_arg = kmalloc(sizeof(struct uti_attr),
@ -10273,7 +10276,7 @@ long syscall(int num, ihk_mc_user_context_t *ctx)
} }
#endif // PROFILE_ENABLE #endif // PROFILE_ENABLE
if (v->flags & CPU_FLAG_NEED_RESCHED) { if (smp_load_acquire(&v->flags) & CPU_FLAG_NEED_RESCHED) {
check_need_resched(); check_need_resched();
} }