Serge Hallyn reports:
"another question: if i run 'restart < out' and sys_restart returns
due to a -EPERM on some object, then restart.c returns 1. but if i
'restart --pids', then it reports the error and returns 0. unless i
add --copy-status to the flags. that seems inconsistent?"
It was with a subtree checkpoint in a child pidns, root-task is not
pid 1, So, the restarts calls ckpt_coordinator_pidns() execution.
In commit 2000bbb4b9... "restart: fix race in ckpt_coordinator_pidns
and --no-wait" adds a pipe for a coordinator in a new pids to report
success/failure of the restart operation back to the parent when the
parent does not wish to wait.
IOW, the coordinator's exit value is overloaded - used once to report
success/failure and once (optionally) to report root-tasks exit status.
This patch fixes this by extending the previous commit to make the
coordinator-pidns always report the restart status via the pipe, and
only use the exit status for --wait --copy-status case.
Signed-off-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
---
restart.c | 25 ++++++++++++-------------
1 files changed, 12 insertions(+), 13 deletions(-)
diff --git a/restart.c b/restart.c
index 35c54ea..5871bbf 100644
--- a/restart.c
+++ b/restart.c
@@ -942,10 +942,12 @@ static int ckpt_coordinator_pidns(struct ckpt_ctx *ctx)
ckpt_dbg("forking coordinator in new pidns\n");
/*
- * We won't wait for (collect) the coordinator, so we use a
- * pipe instead for the coordinator to report success/failure.
+ * The coordinator report restart susccess/failure via pipe.
+ * (It cannot use return value, because the in the default
+ * --wait --copy-status case it is already used to report the
+ * root-task's return value).
*/
- if (!ctx->args->wait && pipe(ctx->pipe_coord)) {
+ if (pipe(ctx->pipe_coord) < 0) {
perror("pipe");
return -1;
}
@@ -981,10 +983,7 @@ static int ckpt_coordinator_pidns(struct ckpt_ctx *ctx)
return -1;
ctx->args->copy_status = copy;
- if (ctx->args->wait)
- return ckpt_collect_child(ctx);
- else
- return ckpt_coordinator_status(ctx);
+ return ckpt_coordinator_status(ctx);
}
#else
static int ckpt_coordinator_pidns(struct ckpt_ctx *ctx)
@@ -1040,13 +1039,13 @@ static int ckpt_coordinator(struct ckpt_ctx *ctx)
* around and be reaper until all tasks are gone.
* Otherwise, container will die as soon as we exit.
*/
- if (!ctx->args->wait) {
- /* report status because parent won't wait for us */
- if (write(ctx->pipe_coord[1], &ret, sizeof(ret)) < 0) {
- perror("failed to report status");
- exit(1);
- }
+
+ /* Report success/failure to the parent */
+ if (write(ctx->pipe_coord[1], &ret, sizeof(ret)) < 0) {
+ perror("failed to report status");
+ exit(1);
}
+
ret = ckpt_pretend_reaper(ctx);
} else if (ctx->args->wait) {
ret = ckpt_collect_child(ctx);
--
1.6.0.4
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