rarias/ovni
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Use atomics to protect libovni process state

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Multiple threads may attempt to initialize or finalize the process, so
we keep the state stored in an atomic integer to protect against bad
usage.
This commit is contained in:
Rodrigo Arias 2024-09-13 08:35:33 +02:00
parent ceaac3bcf0
commit f6fc166a38
1 changed files with 38 additions and 23 deletions
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61
src/rt/ovni.c
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@ -5,6 +5,8 @@
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <stdatomic.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
@ -19,6 +21,13 @@
#include "version.h"
#include "utlist.h"
enum {
ST_UNINIT = 0,
ST_INIT,
ST_READY,
ST_GONE,
};
struct ovni_rcpu {
int index;
int phyid;
@ -73,8 +82,7 @@ struct ovni_rproc {
int rank;
int nranks;
int ready;
int finished;
atomic_int st;
JSON_Value *meta;
};
@ -171,8 +179,8 @@ ovni_add_cpu(int index, int phyid)
if (phyid < 0)
die("cannot use negative CPU id %d", phyid);
if (!rproc.ready)
die("process not yet initialized");
if (rproc.st != ST_READY)
die("process not ready");
if (!rthread.ready)
die("thread not yet initialized");
@ -190,8 +198,8 @@ ovni_add_cpu(int index, int phyid)
void
ovni_proc_set_rank(int rank, int nranks)
{
if (!rproc.ready)
die("process not yet initialized");
if (rproc.st != ST_READY)
die("process not ready");
rproc.rank_set = 1;
rproc.rank = rank;
@ -237,13 +245,19 @@ create_proc_dir(const char *loom, int pid)
void
ovni_proc_init(int app, const char *loom, int pid)
{
if (rproc.ready)
die("pid %d already initialized", pid);
/* Protect against two threads calling at the same time */
int st = ST_UNINIT;
bool was_uninit = atomic_compare_exchange_strong(&rproc.st,
&st, ST_INIT);
if (rproc.finished)
die("pid %d has finished, cannot init again", pid);
memset(&rproc, 0, sizeof(rproc));
if (!was_uninit) {
if (st == ST_INIT)
die("pid %d already being initialized", pid);
else if (st == ST_READY)
die("pid %d already initialized", pid);
else if (st == ST_GONE)
die("pid %d has finished, cannot init again", pid);
}
if (strlen(loom) >= OVNI_MAX_HOSTNAME)
die("loom name too long: %s", loom);
@ -255,7 +269,7 @@ ovni_proc_init(int app, const char *loom, int pid)
create_proc_dir(loom, pid);
rproc.ready = 1;
rproc.st = ST_READY;
}
static int
@ -353,18 +367,19 @@ try_clean_dir(const char *dir)
void
ovni_proc_fini(void)
{
if (!rproc.ready)
die("process not initialized");
/* Protect against two threads calling at the same time */
int st = ST_READY;
bool was_ready = atomic_compare_exchange_strong(&rproc.st,
&st, ST_GONE);
if (!was_ready)
die("process not ready");
if (rproc.move_to_final) {
try_clean_dir(rproc.procdir);
try_clean_dir(rproc.loomdir);
try_clean_dir(rproc.tmpdir);
}
/* Mark the process no longer ready */
rproc.finished = 1;
rproc.ready = 0;
}
static void
@ -516,8 +531,8 @@ ovni_thread_init(pid_t tid)
if (tid == 0)
die("cannot use tid=%d", tid);
if (!rproc.ready)
die("process not yet initialized");
if (rproc.st != ST_READY)
die("process not ready");
memset(&rthread, 0, sizeof(rthread));
@ -751,8 +766,8 @@ ovni_flush(void)
if (!rthread.ready)
die("thread is not initialized");
if (!rproc.ready)
die("process is not initialized");
if (rproc.st != ST_READY)
die("process not ready");
ovni_ev_set_clock(&pre, ovni_clock_now());
ovni_ev_set_mcv(&pre, "OF[");