We use clone and eclone directly and not through glibc, therefore must explicitly care about thread-safety of malloc.
This patch eliminates the use of malloc() from ckpt_fork_child(). The malloc was needed to make a pid-array for eclone using data from the vpids from the checkpoint image. In particular, it added the 0th level pid. Instead, we re-package vpids array early on by expanding the array and pre-adding 0th pids before any of the forks take place. Signed-off-by: Oren Laadan <[email protected]> --- restart.c | 82 ++++++++++++++++++++++++++++++++---------------------------- 1 files changed, 44 insertions(+), 38 deletions(-) diff --git a/restart.c b/restart.c index b281ca2..b274e37 100644 --- a/restart.c +++ b/restart.c @@ -1725,9 +1725,9 @@ static pid_t ckpt_fork_child(struct ckpt_ctx *ctx, struct task *child) unsigned long flags = SIGCHLD; pid_t pid = 0; pid_t *pids = &pid; - int i, j, depth; + int i, depth; - ckpt_dbg("forking child vpid %d flags %#x\n", child->pid, child->flags); + ckpt_dbg("fork child vpid %d flags %#x\n", child->pid, child->flags); stk = genstack_alloc(PTHREAD_STACK_MIN); if (!stk) { @@ -1747,17 +1747,7 @@ static pid_t ckpt_fork_child(struct ckpt_ctx *ctx, struct task *child) depth = child->piddepth + 1; clone_args.nr_pids = depth; - pids = malloc(sizeof(pid_t) * depth); - if (!pids) { - perror("ckpt_fork_child pids malloc"); - return -1; - } - - memset(pids, 0, sizeof(pid_t) * depth); - pids[0] = child->pid; - - for (i = child->piddepth - 1, j = 0; i >= 0; i--, j++) - pids[j + 1] = ctx->vpids_arr[child->vidx + j]; + pids = &ctx->vpids_arr[child->vidx]; #ifndef CLONE_NEWPID if (child->piddepth > child->creator->piddepth) { @@ -1810,9 +1800,6 @@ static pid_t ckpt_fork_child(struct ckpt_ctx *ctx, struct task *child) if (pid < 0 || !(child->flags & TASK_THREAD)) genstack_release(stk); - if (pids != &pid) - free(pids); - ckpt_dbg("forked child vpid %d (asked %d)\n", pid, child->pid); return pid; } @@ -2336,34 +2323,53 @@ static int ckpt_read_tree(struct ckpt_ctx *ctx) return ret; } -/* set the vpids pointers in all the tasks */ +/* + * transform vpids arrays to the format convenient for eclone: + * prefix the level 0 pid to every sequence of nested pids. + * also, set the vpids pointers in all the tasks. + */ static int assign_vpids(struct ckpt_ctx *ctx) { - int d, hidx, tidx; - struct task *t; + __s32 *vpids_arr; + int depth, hidx, vidx, tidx; + struct task *task; - for (hidx = 0, tidx = 0; tidx < ctx->pids_nr; tidx++) { - t = &ctx->tasks_arr[tidx]; - d = t->piddepth = ctx->pids_arr[tidx].depth; - if (!d) { - ckpt_dbg("task[%d].vidx = -1\n", tidx); - t->vidx = -1; - continue; - } - t->vidx = hidx; + vpids_arr = malloc(sizeof(__s32) * (ctx->vpids_nr + ctx->pids_nr)); + if (vpids_arr == NULL) { + perror("assign_vpids malloc"); + return -1; + } + + for (tidx = 0, hidx = 0, vidx = 0; tidx < ctx->pids_nr; tidx++) { + task = &ctx->tasks_arr[tidx]; + depth = ctx->pids_arr[tidx].depth; + + task->vidx = vidx; + task->piddepth = depth; + + /* set task's and top level pid */ + vpids_arr[vidx++] = task->pid; + /* copy task's nested pids */ + memcpy(&vpids_arr[vidx], &ctx->vpids_arr[hidx], + sizeof(__s32) * depth); + + vidx += depth; + hidx += depth; + +#ifdef CHECKPOINT_DEBUG ckpt_dbg("task[%d].vidx = %d (depth %d, rpid %d)\n", - tidx, hidx, t->piddepth, ctx->pids_arr[tidx].vpid); - int i; - for (i=0; i<t->piddepth; i++) - ckpt_dbg("task[%d].vpid[%d] = %d\n", tidx, i, - ctx->vpids_arr[hidx+i]); - hidx += d; - if (hidx > ctx->vpids_nr) { - ckpt_err("Error parsing vpids array"); - return -1; + tidx, vidx, depth, ctx->pids_arr[tidx].vpid); + while (depth-- > 0) { + ckpt_dbg("task[%d].vpid[%d] = %d\n", tidx, + depth, vpids_arr[hidx - depth - 1]); } +#endif } + /* relpace "raw" vpids_arr with this one */ + free(ctx->vpids_arr); + ctx->vpids_arr = vpids_arr; + return 0; } -- 1.7.0.4 _______________________________________________ Containers mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list [email protected] https://openvz.org/mailman/listinfo/devel
