We don't support multiple devpts mounts in a container. So
bail on checkpoint if a container has them. This will cause
checkpoint to fail of a container which still has a pty from
parent container in use.
Since I don't actually need any methods in the ckpt_ops for
ptsns, I just register the ckpt_ops in tty_io.c which is never
a module. We will presumably have to deal with modular ckpt_ops
after the next submission, and we've talked about how to do it,
but it's kind of late in this cycle to do that now.
checkpointing a task with open fd to pty from parent ns results
in a message like:
[err -16][pos 3382][E @ tty_file_checkpoint:2760]Open pty from alien ptsns
Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
drivers/char/tty_io.c | 32 ++++++++++++++++++++++++++++++++
include/linux/checkpoint_hdr.h | 18 ++++++++++++++++++
include/linux/checkpoint_types.h | 2 ++
3 files changed, 52 insertions(+), 0 deletions(-)
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index d264000..999317c 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -96,6 +96,7 @@
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/seq_file.h>
+#include <linux/mount.h>
#include <linux/uaccess.h>
#include <asm/system.h>
@@ -2687,6 +2688,27 @@ static int tty_can_checkpoint(struct ckpt_ctx *ctx, struct tty_struct *tty)
return 1;
}
+/*
+ * If tty_file_checkpoint() ever supports more than unix98 ptys we'll have
+ * to check for that
+ */
+static int detect_multiple_ptsns(struct ckpt_ctx *ctx, struct file *file)
+{
+ int objref;
+ int new;
+
+ objref = ckpt_obj_lookup_add(ctx, file->f_path.mnt->mnt_sb,
+ CKPT_OBJ_PTS_NS, &new);
+ if (objref < 0)
+ return objref;
+ if (new && ctx->num_devpts_ns)
+ return -EBUSY;
+ if (file->f_path.mnt->mnt_ns != ctx->root_nsproxy->mnt_ns)
+ return -EBUSY;
+ ctx->num_devpts_ns++;
+ return 0;
+}
+
static int tty_file_checkpoint(struct ckpt_ctx *ctx, struct file *file)
{
struct ckpt_hdr_file_tty *h;
@@ -2732,6 +2754,11 @@ static int tty_file_checkpoint(struct ckpt_ctx *ctx, struct file *file)
ret = ckpt_write_obj(ctx, &h->common.h);
ckpt_hdr_put(ctx, h);
+
+ ret = detect_multiple_ptsns(ctx, file);
+ if (ret)
+ ckpt_err(ctx, ret, "Open pty from alien ptsns\n");
+
return ret;
}
@@ -3680,6 +3707,8 @@ static struct cdev tty_cdev, console_cdev;
*/
static int __init tty_init(void)
{
+ int err;
+
cdev_init(&tty_cdev, &tty_fops);
if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
@@ -3698,6 +3727,9 @@ static int __init tty_init(void)
vty_init(&console_fops);
#endif
#ifdef CONFIG_CHECKPOINT
+ err = register_checkpoint_obj(&ckpt_obj_ptsns_ops);
+ if (err)
+ return err;
return checkpoint_register_tty();
#else
return 0;
diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
index eb5e1b4..27113ca 100644
--- a/include/linux/checkpoint_hdr.h
+++ b/include/linux/checkpoint_hdr.h
@@ -271,6 +271,8 @@ enum obj_type {
#define CKPT_OBJ_NET_NS CKPT_OBJ_NET_NS
CKPT_OBJ_NETDEV,
#define CKPT_OBJ_NETDEV CKPT_OBJ_NETDEV
+ CKPT_OBJ_PTS_NS,
+#define CKPT_OBJ_PTS_NS CKPT_OBJ_PTS_NS
CKPT_OBJ_MAX
#define CKPT_OBJ_MAX CKPT_OBJ_MAX
};
@@ -1142,5 +1144,21 @@ struct ckpt_hdr_ldisc_n_tty {
#define CKPT_TST_OVERFLOW_64(a, b) \
((sizeof(a) > sizeof(b)) && ((a) > LONG_MAX))
+#if defined(CONFIG_UNIX98_PTYS) || defined(CONFIG_UNIX98_PTYS_MODULE)
+/*
+ * We don't yet support multiple pts mounts in a container, so
+ * all we're doing here is detecting pty's in >1 ptsns. We'll
+ * actually stick the sb on the objhash because that's all there
+ * is. Note that means that when we start checkpointing mounts
+ * and filesystems we'll need to change this.
+ *
+ * We don't need to pin these bc they are pinned by the pty,
+ * which we do have pinned.
+ */
+static const struct ckpt_obj_ops ckpt_obj_ptsns_ops = {
+ .obj_name = "PTS NS",
+ .obj_type = CKPT_OBJ_PTS_NS,
+};
+#endif /* CONFIG_UNIX98_PTYS */
#endif /* _CHECKPOINT_CKPT_HDR_H_ */
diff --git a/include/linux/checkpoint_types.h b/include/linux/checkpoint_types.h
index eb3fdac..84782b0 100644
--- a/include/linux/checkpoint_types.h
+++ b/include/linux/checkpoint_types.h
@@ -86,6 +86,8 @@ struct ckpt_ctx {
struct cred *realcred, *ecred; /* tmp storage for cred at restart */
struct list_head listen_sockets;/* listening parent sockets */
+ int num_devpts_ns; /* must not become > 1 at the moment */
+
struct ckpt_stats stats; /* statistics */
#define CKPT_MSG_LEN 1024
--
1.7.0.4
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