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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>,
	Davidlohr Bueso <dbueso@suse.de>, Jason Baron <jbaron@akamai.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrea Parri <andrea.parri@amarulasolutions.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFC PATCH 06/15] epoll: introduce various of helpers for user structure lengths calculations
Date: Wed,  9 Jan 2019 17:40:16 +0100
Message-ID: <20190109164025.24554-7-rpenyaev@suse.de> (raw)
In-Reply-To: <20190109164025.24554-1-rpenyaev@suse.de>

Helpers for lengths-from-number and number-from-lengths calculations.
Among them:

  ep_polled_by_user()
	- returns true if epoll was created with EPOLL_USERPOLL

  ep_user_ring_events_available()
	- returns true if there is something in user ring buffer

Signed-off-by: Roman Penyaev <rpenyaev@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrea Parri <andrea.parri@amarulasolutions.com>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 fs/eventpoll.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 9ec682b6488f..ae288f62aa4c 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -438,6 +438,65 @@ static void ep_nested_calls_init(struct nested_calls *ncalls)
 	spin_lock_init(&ncalls->lock);
 }
 
+static inline unsigned int to_items_length(unsigned int nr)
+{
+	struct eventpoll *ep;
+
+	return (sizeof(*ep->user_header) +
+		(nr << ilog2(sizeof(ep->user_header->items[0]))));
+}
+
+static inline unsigned int to_index_length(unsigned int nr)
+{
+	struct eventpoll *ep;
+
+	return nr << ilog2(sizeof(*ep->user_index));
+}
+
+static inline unsigned int to_items_bm_length(unsigned int nr)
+{
+	return ALIGN(nr, 8) >> 3;
+}
+
+static inline unsigned int to_items_nr(unsigned int len)
+{
+	struct eventpoll *ep;
+
+	return (len - sizeof(*ep->user_header)) >>
+		ilog2(sizeof(ep->user_header->items[0]));
+}
+
+static inline unsigned int to_items_bm_nr(unsigned int len)
+{
+	return len << 3;
+}
+
+static inline unsigned int ep_max_items_nr(struct eventpoll *ep)
+{
+	return to_items_nr(ep->header_length);
+}
+
+static inline unsigned int ep_max_index_nr(struct eventpoll *ep)
+{
+	return ep->index_length >> ilog2(sizeof(*ep->user_index));
+}
+
+static inline unsigned int ep_max_items_bm_nr(struct eventpoll *ep)
+{
+	return to_items_bm_nr(ep->items_bm_length);
+}
+
+static inline bool ep_polled_by_user(struct eventpoll *ep)
+{
+	return !!ep->user_header;
+}
+
+static inline bool ep_user_ring_events_available(struct eventpoll *ep)
+{
+	return ep_polled_by_user(ep) &&
+		ep->user_header->head != ep->user_header->tail;
+}
+
 /**
  * ep_events_available - Checks if ready events might be available.
  *
-- 
2.19.1


  parent reply index

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-09 16:40 [RFC 00/15] epoll: support pollable epoll from userspace Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 01/15] mm/vmalloc: add new 'alignment' field for vm_struct structure Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 02/15] mm/vmalloc: move common logic from __vmalloc_area_node to a separate func Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 03/15] mm/vmalloc: introduce new vrealloc() call and its subsidiary reach analog Roman Penyaev
2019-01-09 16:50   ` Matthew Wilcox
2019-01-10 10:08     ` Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 04/15] epoll: move private helpers from a header to the source Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 05/15] epoll: introduce user header structure and user index for polling from userspace Roman Penyaev
2019-01-09 16:40 ` Roman Penyaev [this message]
2019-01-09 16:40 ` [RFC PATCH 07/15] epoll: extend epitem struct with new members " Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 08/15] epoll: some sanity flags checks for epoll syscalls for polled epfd " Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 09/15] epoll: introduce stand-alone helpers for polling " Roman Penyaev
2019-01-09 17:29   ` Linus Torvalds
2019-01-10 10:03     ` Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 10/15] epoll: support polling from userspace for ep_insert() Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 11/15] epoll: offload polling to a work in case of epfd polled from userspace Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 12/15] epoll: support polling from userspace for ep_remove() Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 13/15] epoll: support polling from userspace for ep_modify() Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 14/15] epoll: support polling from userspace for ep_poll() Roman Penyaev
2019-01-09 16:40 ` [RFC PATCH 15/15] epoll: support mapping for epfd when polled from userspace Roman Penyaev

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