Messages in this thread Patch in this message | | | From | Oren Laadan <> | Subject | [RFC v10][PATCH 10/13] External checkpoint of a task other than ourself | Date | Wed, 26 Nov 2008 20:04:41 -0500 |
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Now we can do "external" checkpoint, i.e. act on another task.
sys_checkpoint() now looks up the target pid (in our namespace) and checkpoints that corresponding task. That task should be the root of a container.
sys_restart() remains the same, as the restart is always done in the context of the restarting task.
Changelog[v10]: - Grab vfs root of container init, rather than current process
Signed-off-by: Oren Laadan <orenl@cs.columbia.edu> Acked-by: Serge Hallyn <serue@us.ibm.com> --- checkpoint/checkpoint.c | 75 ++++++++++++++++++++++++++++++++++++++++++-- checkpoint/restart.c | 4 +- checkpoint/sys.c | 6 +++ include/linux/checkpoint.h | 2 + 4 files changed, 82 insertions(+), 5 deletions(-)
diff --git a/checkpoint/checkpoint.c b/checkpoint/checkpoint.c index ae1952b..08719ba 100644 --- a/checkpoint/checkpoint.c +++ b/checkpoint/checkpoint.c @@ -10,6 +10,7 @@ #include <linux/version.h> #include <linux/sched.h> +#include <linux/ptrace.h> #include <linux/time.h> #include <linux/fs.h> #include <linux/file.h> @@ -224,6 +225,13 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t) { int ret; + /* TODO: verity that the task is frozen (unless self) */ + + if (t->state == TASK_DEAD) { + pr_warning("c/r: task may not be in state TASK_DEAD\n"); + return -EAGAIN; + } + ret = cr_write_task_struct(ctx, t); cr_debug("task_struct: ret %d\n", ret); if (ret < 0) @@ -246,15 +254,76 @@ static int cr_write_task(struct cr_ctx *ctx, struct task_struct *t) return ret; } -static int cr_ctx_checkpoint(struct cr_ctx *ctx, pid_t pid) +static int cr_get_container(struct cr_ctx *ctx, pid_t pid) { + struct task_struct *task = NULL; + struct nsproxy *nsproxy = NULL; + int err = -ESRCH; + ctx->root_pid = pid; + read_lock(&tasklist_lock); + task = find_task_by_vpid(pid); + if (task) + get_task_struct(task); + read_unlock(&tasklist_lock); + + if (!task) + goto out; + +#if 0 /* enable to use containers */ + if (!is_container_init(task)) { + err = -EINVAL; + goto out; + } +#endif + + if (!ptrace_may_access(task, PTRACE_MODE_READ)) { + err = -EPERM; + goto out; + } + + rcu_read_lock(); + if (task_nsproxy(task)) { + nsproxy = task_nsproxy(task); + get_nsproxy(nsproxy); + } + rcu_read_unlock(); + + if (!nsproxy) + goto out; + + /* TODO: verify that the container is frozen */ + + ctx->root_task = task; + ctx->root_nsproxy = nsproxy; + + return 0; + + out: + if (task) + put_task_struct(task); + return err; +} + +/* setup checkpoint-specific parts of ctx */ +static int cr_ctx_checkpoint(struct cr_ctx *ctx, pid_t pid) +{ + int ret; + + ret = cr_get_container(ctx, pid); + if (ret < 0) + return ret; + /* * assume checkpointer is in container's root vfs * FIXME: this works for now, but will change with real containers */ - ctx->vfsroot = ¤t->fs->root; + task_lock(ctx->root_task); + ctx->vfsroot = &ctx->root_task->fs->root; + task_unlock(ctx->root_task); + if (!ctx->vfsroot) + return -EAGAIN; path_get(ctx->vfsroot); return 0; @@ -270,7 +339,7 @@ int do_checkpoint(struct cr_ctx *ctx, pid_t pid) ret = cr_write_head(ctx); if (ret < 0) goto out; - ret = cr_write_task(ctx, current); + ret = cr_write_task(ctx, ctx->root_task); if (ret < 0) goto out; ret = cr_write_tail(ctx); diff --git a/checkpoint/restart.c b/checkpoint/restart.c index 22e7995..f4f737d 100644 --- a/checkpoint/restart.c +++ b/checkpoint/restart.c @@ -277,7 +277,7 @@ static int cr_read_task(struct cr_ctx *ctx) } /* setup restart-specific parts of ctx */ -static int cr_ctx_restart(struct cr_ctx *ctx) +static int cr_ctx_restart(struct cr_ctx *ctx, pid_t pid) { return 0; } @@ -286,7 +286,7 @@ int do_restart(struct cr_ctx *ctx, pid_t pid) { int ret; - ret = cr_ctx_restart(ctx); + ret = cr_ctx_restart(ctx, pid); if (ret < 0) goto out; ret = cr_read_head(ctx); diff --git a/checkpoint/sys.c b/checkpoint/sys.c index b640bee..dfe63ca 100644 --- a/checkpoint/sys.c +++ b/checkpoint/sys.c @@ -9,6 +9,7 @@ */ #include <linux/sched.h> +#include <linux/nsproxy.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/file.h> @@ -142,6 +143,11 @@ static void cr_ctx_free(struct cr_ctx *ctx) cr_pgarr_free(ctx); cr_objhash_free(ctx); + if (ctx->root_nsproxy) + put_nsproxy(ctx->root_nsproxy); + if (ctx->root_task) + put_task_struct(ctx->root_task); + kfree(ctx); } diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h index 2675410..93fea2f 100644 --- a/include/linux/checkpoint.h +++ b/include/linux/checkpoint.h @@ -19,6 +19,8 @@ struct cr_ctx { int crid; /* unique checkpoint id */ pid_t root_pid; /* container identifier */ + struct task_struct *root_task; /* container root task */ + struct nsproxy *root_nsproxy; /* container root nsproxy */ unsigned long flags; unsigned long oflags; /* restart: old flags */ -- 1.5.4.3
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