Quoting Matt Helsley (matthltc@xxxxxxxxxx):
> Save/restore eventfd files. These are anon_inodes just like epoll
> but instead of a set of files to poll they are a 64-bit counter
> and a flag value. Used for AIO.
>
> Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
>
> NOTE: Marked [RFC] because it strangely does not pass my adapted LTP
> test cases unless it's running from a checkpointed image.
> Seems to be a mistake in the test case adaptation.
> ---
> checkpoint/files.c | 7 +++++
> fs/eventfd.c | 51 ++++++++++++++++++++++++++++++++++++++++
> include/linux/checkpoint_hdr.h | 8 ++++++
> include/linux/eventfd.h | 10 ++++++++
> 4 files changed, 76 insertions(+), 0 deletions(-)
>
> diff --git a/checkpoint/files.c b/checkpoint/files.c
> index f6de07e..43b95cc 100644
> --- a/checkpoint/files.c
> +++ b/checkpoint/files.c
> @@ -23,6 +23,7 @@
> #include <linux/checkpoint.h>
> #include <linux/checkpoint_hdr.h>
> #include <net/sock.h>
> +#include <linux/eventfd.h>
>
>
> /**************************************************************************
> @@ -607,6 +608,12 @@ static struct restore_file_ops restore_file_ops[] = {
> .file_type = CKPT_FILE_TTY,
> .restore = tty_file_restore,
> },
> + /* eventfd */
> + {
> + .file_name = "EVENTFD",
> + .file_type = CKPT_FILE_EVENTFD,
> + .restore = eventfd_restore,
> + },
> };
>
> static struct file *do_restore_file(struct ckpt_ctx *ctx)
> diff --git a/fs/eventfd.c b/fs/eventfd.c
> index 31d12de..5d30cd5 100644
> --- a/fs/eventfd.c
> +++ b/fs/eventfd.c
> @@ -18,6 +18,8 @@
> #include <linux/module.h>
> #include <linux/kref.h>
> #include <linux/eventfd.h>
> +#include <linux/checkpoint.h>
> +#include <linux/checkpoint_hdr.h>
>
> struct eventfd_ctx {
> struct kref kref;
> @@ -223,11 +225,34 @@ static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t c
> return res;
> }
>
> +static int eventfd_checkpoint(struct ckpt_ctx *ckpt_ctx, struct file *file)
> +{
> + struct eventfd_ctx *ctx;
> + struct ckpt_hdr_file_eventfd *h;
> + int ret = -ENOMEM;
> +
> + h = ckpt_hdr_get_type(ckpt_ctx, sizeof(*h), CKPT_HDR_FILE);
> + if (!h)
> + return -ENOMEM;
> + h->common.f_type = CKPT_FILE_EVENTFD;
> + ret = checkpoint_file_common(ckpt_ctx, file, &h->common);
> + if (ret < 0)
> + goto out;
> + ctx = file->private_data;
> + h->count = ctx->count;
I only took a very cursory glance at the eventfd code, but eventfd_poll()
suggests that ULLONG_MAX is a valid value for ctx->count (suggesting error).
Should you be checking for that? (Or is that a special case that will
never be checkpointed somehow?)
> + h->flags = ctx->flags;
> + ret = ckpt_write_obj(ckpt_ctx, &h->common.h);
> +out:
> + ckpt_hdr_put(ckpt_ctx, h);
> + return ret;
> +}
> +
> static const struct file_operations eventfd_fops = {
> .release = eventfd_release,
> .poll = eventfd_poll,
> .read = eventfd_read,
> .write = eventfd_write,
> + .checkpoint = eventfd_checkpoint,
> };
>
> /**
> @@ -335,3 +360,29 @@ SYSCALL_DEFINE1(eventfd, unsigned int, count)
> return sys_eventfd2(count, 0);
> }
>
> +struct file *eventfd_restore(struct ckpt_ctx *ckpt_ctx,
> + struct ckpt_hdr_file *ptr)
> +{
> + struct ckpt_hdr_file_eventfd *h = (struct ckpt_hdr_file_eventfd *)ptr;
> + struct file *evfile;
> + int evfd, ret;
> +
> + /* Already know type == CKPT_HDR_FILE and f_type == CKPT_FILE_EVENTFD */
> + if (h->common.h.len != sizeof(*h))
> + return ERR_PTR(-EINVAL);
> +
> + evfd = sys_eventfd2(h->count, h->flags);
> + if (evfd < 0)
> + return ERR_PTR(evfd);
> + evfile = fget(evfd);
> + sys_close(evfd);
> + if (!evfile)
> + return ERR_PTR(-EBUSY);
> +
> + ret = restore_file_common(ckpt_ctx, evfile, &h->common);
> + if (ret < 0) {
> + fput(evfile);
> + return ERR_PTR(ret);
> + }
> + return evfile;
> +}
> diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
> index ff2e4aa..dc22244 100644
> --- a/include/linux/checkpoint_hdr.h
> +++ b/include/linux/checkpoint_hdr.h
> @@ -476,6 +476,8 @@ enum file_type {
> #define CKPT_FILE_SOCKET CKPT_FILE_SOCKET
> CKPT_FILE_TTY,
> #define CKPT_FILE_TTY CKPT_FILE_TTY
> + CKPT_FILE_EVENTFD,
> +#define CKPT_FILE_EVENTFD CKPT_FILE_EVENTFD
> CKPT_FILE_MAX
> #define CKPT_FILE_MAX CKPT_FILE_MAX
> };
> @@ -500,6 +502,12 @@ struct ckpt_hdr_file_pipe {
> __s32 pipe_objref;
> } __attribute__((aligned(8)));
>
> +struct ckpt_hdr_file_eventfd {
> + struct ckpt_hdr_file common;
> + __u64 count;
> + __u32 flags;
> +} __attribute__((aligned(8)));
> +
> /* socket */
> struct ckpt_hdr_socket {
> struct ckpt_hdr h;
> diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
> index 3b85ba6..a904633 100644
> --- a/include/linux/eventfd.h
> +++ b/include/linux/eventfd.h
> @@ -34,6 +34,15 @@ struct eventfd_ctx *eventfd_ctx_fdget(int fd);
> struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
> int eventfd_signal(struct eventfd_ctx *ctx, int n);
>
> +#ifdef CONFIG_CHECKPOINT
> +struct ckpt_ctx;
> +struct ckpt_hdr_file;
> +
> +struct file *eventfd_restore(struct ckpt_ctx *ckpt_ctx,
> + struct ckpt_hdr_file *ptr);
> +#else
> +#define eventfd_restore NULL
> +#endif
> #else /* CONFIG_EVENTFD */
>
> /*
> @@ -55,6 +64,7 @@ static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
>
> }
>
> +#define eventfd_restore NULL
> #endif
>
> #endif /* _LINUX_EVENTFD_H */
> --
> 1.5.6.3
>
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