Matt Helsley wrote:
> Save/restore epoll items during checkpoint/restart respectively.
> kmalloc failures should be dealt with more kindly than just error-out
> because epoll is made to poll many thousands of file descriptors.
> Subsequent patches will change epoll c/r to "chunk" its output/input
> respectively.
>
> Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
Acked-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
See one comment below (fixed).
Also fixed is the BUG_ON pointed out by Serge.
Oren.
>
> Changelog:
>
> v5:
> Fix potential recursion during collect.
> Replace call to ckpt_obj_collect() with ckpt_collect_file().
> [Oren]
> Fix checkpoint leak detection when there are more items than
> expected.
> Cleanup/simplify error write paths. (will complicate in a later
> patch) [Oren]
> Remove files_deferq bits. [Oren]
> Remove extra newline. [Oren]
> Remove aggregate check on number of watches added. [Oren]
> This is OK since these will be done individually anyway.
> Remove check for negative objrefs during restart. [Oren]
> Fixup comment regarding race that indicates checkpoint leaks.
> [Oren]
> s/ckpt_read_obj/ckpt_read_buf_type/ [Oren]
> Patch for lots of epoll items follows.
> Moved sys_close(epfd) right under fget(). [Oren]
> Use CKPT_HDR_BUFFER rather than custome ckpt_read/write_*
> This makes it more similar to the pid array code. [Oren]
> It also simplifies the error recovery paths.
> Tested polling a pipe and 50,000 UNIX sockets.
>
> v4: ckpt-v18
> Use files_deferq as submitted by Dan Smith
> Cleanup to only report >= 1 items when debugging.
>
> v3: [unposted]
> Removed most of the TODOs -- the remainder will be removed by
> subsequent patches.
> Fixed missing ep_file_collect() [Serge]
> Rather than include checkpoint_hdr.h declare (but do not define)
> the two structs needed in eventpoll.h [Oren]
> Complain with ckpt_write_err() when we detect checkpoint obj
> leaks. [Oren]
> Remove redundant is_epoll_file() check in collect. [Oren]
> Move epfile_objref lookup to simplify error handling. [Oren]
> Simplify error handling with early return in
> ep_eventpoll_checkpoint(). [Oren]
> Cleaned up a comment. [Oren]
> Shorten CKPT_HDR_FILE_EPOLL_ITEMS (-FILE) [Oren]
> Renumbered to indicate that it follows the file table.
> Renamed the epoll struct in checkpoint_hdr.h [Oren]
> Also renamed substruct.
> Fixup return of empty ep_file_restore(). [Oren]
> Changed some error returns. [Oren]
> Changed some tests to BUG_ON(). [Oren]
> Factored out watch insert with epoll_ctl() into do_epoll_ctl().
> [Cedric, Oren]
> Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
> ---
> checkpoint/files.c | 8 +
> fs/eventpoll.c | 308 ++++++++++++++++++++++++++++++++++++----
> include/linux/checkpoint_hdr.h | 18 +++
> include/linux/eventpoll.h | 17 ++-
> 4 files changed, 322 insertions(+), 29 deletions(-)
>
> diff --git a/checkpoint/files.c b/checkpoint/files.c
> index f6de07e..6ea2389 100644
> --- a/checkpoint/files.c
> +++ b/checkpoint/files.c
> @@ -22,6 +22,7 @@
> #include <linux/deferqueue.h>
> #include <linux/checkpoint.h>
> #include <linux/checkpoint_hdr.h>
> +#include <linux/eventpoll.h>
> #include <net/sock.h>
>
>
> @@ -607,6 +608,13 @@ static struct restore_file_ops restore_file_ops[] = {
> .file_type = CKPT_FILE_TTY,
> .restore = tty_file_restore,
> },
> +#ifdef CONFIG_EPOLL
> + {
> + .file_name = "EPOLL",
> + .file_type = CKPT_FILE_EPOLL,
> + .restore = ep_file_restore,
> + },
> +#endif
There must be an entry here even if CONFIG_EPOLL isn't selected. And
indeed you define ep_file_restore() for this case to return -ENOSYS
(toward the end of this patch). So I dropped the #ifdef/#endif pair.
[...]
> diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
> index f6856a5..34538be 100644
> --- a/include/linux/eventpoll.h
> +++ b/include/linux/eventpoll.h
> @@ -56,6 +56,9 @@ struct file;
>
>
> #ifdef CONFIG_EPOLL
> +struct ckpt_ctx;
> +struct ckpt_hdr_file;
> +
>
> /* Used to initialize the epoll bits inside the "struct file" */
> static inline void eventpoll_init_file(struct file *file)
> @@ -95,11 +98,23 @@ static inline void eventpoll_release(struct file *file)
> eventpoll_release_file(file);
> }
>
> -#else
>
> +#ifdef CONFIG_CHECKPOINT
> +extern struct file* ep_file_restore(struct ckpt_ctx *ctx,
> + struct ckpt_hdr_file *h);
> +#endif
> +#else
> +/* !defined(CONFIG_EPOLL) */
> static inline void eventpoll_init_file(struct file *file) {}
> static inline void eventpoll_release(struct file *file) {}
>
> +#ifdef CONFIG_CHECKPOINT
> +static inline struct file* ep_file_restore(struct ckpt_ctx *ctx,
> + struct ckpt_hdr_file *ptr)
> +{
> + return ERR_PTR(-ENOSYS);
> +}
> +#endif
> #endif
>
> #endif /* #ifdef __KERNEL__ */
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