linux-kernel - [RFC PATCH 06/15] epoll: introduce various of helpers for user structure lengths calculations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190109164025.24554-7-rpenyaev@suse.de>
Date:   Wed,  9 Jan 2019 17:40:16 +0100
From:   Roman Penyaev <rpenyaev@...e.de>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Roman Penyaev <rpenyaev@...e.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Davidlohr Bueso <dbueso@...e.de>,
        Jason Baron <jbaron@...mai.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrea Parri <andrea.parri@...rulasolutions.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 06/15] epoll: introduce various of helpers for user structure lengths calculations

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@...e.de>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Davidlohr Bueso <dbueso@...e.de>
Cc: Jason Baron <jbaron@...mai.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Andrea Parri <andrea.parri@...rulasolutions.com>
Cc: linux-fsdevel@...r.kernel.org
Cc: linux-kernel@...r.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