From: Roman Penyaev <rpenyaev@suse.de>
To: unlisted-recipients:; (no To-header on input)
Cc: Roman Penyaev <rpenyaev@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 02/14] epoll: introduce user structures for polling from userspace
Date: Tue, 11 Jun 2019 16:54:46 +0200 [thread overview]
Message-ID: <20190611145458.9540-3-rpenyaev@suse.de> (raw)
In-Reply-To: <20190611145458.9540-1-rpenyaev@suse.de>
This one introduces structures of user items array:
struct epoll_uheader -
describes inserted epoll items.
struct epoll_uitem -
single epoll item visible to userspace.
Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
fs/eventpoll.c | 11 +++++++++++
include/uapi/linux/eventpoll.h | 29 +++++++++++++++++++++++++++++
2 files changed, 40 insertions(+)
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 50bb99e98872..90dc75ad4144 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -4,6 +4,7 @@
* Copyright (C) 2001,...,2009 Davide Libenzi
*
* Davide Libenzi <davidel@xmailserver.org>
+ * Polling from userspace support by Roman Penyaev <rpenyaev@suse.de>
*/
#include <linux/init.h>
@@ -104,6 +105,16 @@
#define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry))
+/*
+ * That is around 1.3mb of allocated memory for one epfd. What is more
+ * important is ->index_length, which should be ^2, so do not increase
+ * max items number to avoid size doubling of user index.
+ *
+ * Before increasing the value see add_event_to_uring() and especially
+ * cnt_to_advance() functions and change them accordingly.
+ */
+#define EP_USERPOLL_MAX_ITEMS_NR 65536
+
struct epoll_filefd {
struct file *file;
int fd;
diff --git a/include/uapi/linux/eventpoll.h b/include/uapi/linux/eventpoll.h
index 39dfc29f0f52..3317901b19c4 100644
--- a/include/uapi/linux/eventpoll.h
+++ b/include/uapi/linux/eventpoll.h
@@ -79,4 +79,33 @@ struct epoll_event {
__u64 data;
} EPOLL_PACKED;
+#define EPOLL_USERPOLL_HEADER_MAGIC 0xeb01eb01
+#define EPOLL_USERPOLL_HEADER_SIZE 128
+
+/*
+ * Item, shared with userspace. Unfortunately we can't embed epoll_event
+ * structure, because it is badly aligned on all 64-bit archs, except
+ * x86-64 (see EPOLL_PACKED). sizeof(epoll_uitem) == 16
+ */
+struct epoll_uitem {
+ __poll_t ready_events;
+ __poll_t events;
+ __u64 data;
+};
+
+/*
+ * Header, shared with userspace. sizeof(epoll_uheader) == 128
+ */
+struct epoll_uheader {
+ __u32 magic; /* epoll user header magic */
+ __u32 header_length; /* length of the header + items */
+ __u32 index_length; /* length of the index ring, always pow2 */
+ __u32 max_items_nr; /* max number of items */
+ __u32 head; /* updated by userland */
+ __u32 tail; /* updated by kernel */
+
+ struct epoll_uitem items[]
+ __attribute__((__aligned__(EPOLL_USERPOLL_HEADER_SIZE)));
+};
+
#endif /* _UAPI_LINUX_EVENTPOLL_H */
--
2.21.0
next prev parent reply other threads:[~2019-06-11 14:56 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-11 14:54 [PATCH v4 00/14] epoll: support pollable epoll from userspace Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 01/14] epoll: move private helpers from a header to the source Roman Penyaev
2019-06-11 14:54 ` Roman Penyaev [this message]
2019-06-11 14:54 ` [PATCH v4 03/14] epoll: allocate user header and user events ring for polling from userspace Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 04/14] epoll: some sanity flags checks for epoll syscalls " Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 05/14] epoll: offload polling to a work in case of epfd polled " Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 06/14] epoll: introduce helpers for adding/removing events to uring Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 07/14] epoll: call ep_add_event_to_uring() from ep_poll_callback() Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 08/14] epoll: support polling from userspace for ep_insert() Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 09/14] epoll: support polling from userspace for ep_remove() Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 10/14] epoll: support polling from userspace for ep_modify() Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 11/14] epoll: support polling from userspace for ep_poll() Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 12/14] epoll: support mapping for epfd when polled from userspace Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 13/14] epoll: implement epoll_create2() syscall Roman Penyaev
2019-06-11 14:54 ` [PATCH v4 14/14] kselftest: add uepoll-test which tests polling from userspace Roman Penyaev
2019-07-26 23:22 ` [PATCH v4 00/14] epoll: support pollable epoll " Andrew Morton
2019-07-27 17:16 ` Eric Wong
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