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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);
mb();
if (!packet->req.valid) {
if (!smp_load_acquire(&packet->req.valid)) {
printk("%s: ERROR: stray wakeup pid: %d, tid: %d: SC %lu\n",
__FUNCTION__,
task_tgid_vnr(current),
@ -1462,7 +1462,7 @@ retry_alloc:
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, "
"args[3]: %lu, args[4]: %lu, args[5]: %lu\n",
__FUNCTION__,

14
executer/kernel/mcctrl/syscall.c
View File

@ -228,18 +228,19 @@ static int __notify_syscall_requester(ihk_os_t os, struct ikc_scd_packet *packet
c = (usrdata->channels + packet->ref)->c;
/* 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_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",
__FUNCTION__, packet->pid);
__FUNCTION__, packet->pid);
return ret;
}
/* 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.
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, "
"pid: %d, req status: %lu, syscall nr: %lu\n",
__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 */
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_TO_BE_WOKEN)) {
IHK_SCD_REQ_THREAD_TO_BE_WOKEN) !=
IHK_SCD_REQ_THREAD_DESCHEDULED) {
printk("%s: WARNING: inconsistent requester status, "
"pid: %d, req status: %lu, syscall nr: %lu\n",
__FUNCTION__, packet->pid,