linux-kernel - [PATCH RT 0/2] rwsem-rt: Make rwsem rt closer to mainline

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-next>] [day] [month] [year] [list]

Date:	Tue, 08 Apr 2014 22:47:00 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	linux-kernel@...r.kernel.org,
	linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Carsten Emde <C.Emde@...dl.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	John Kacur <jkacur@...hat.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH RT 0/2] rwsem-rt: Make rwsem rt closer to mainline

Looking at mainline's down_read() I noticed that reader locks of rwsems
are not made to nest. In fact, they should not. Although, it may seem
fine if a down_read() nests as multiple readers can have the lock,
rwsems are fair locks. That is, if a writer were to block on a rwsem
while readers have the lock, a new reader will also block. If a reader
were to try to take the lock again while a writer was waiting, it
would block, and cause a deadlock as it has the lock its trying
to grab and wont let it go as the writer is waiting.

I also found that the rt_mutex_init() is identical in the two places
it is defined in rtmutex.h.

Steven Rostedt (Red Hat) (2):
      rwsem-rt: Do not allow readers to nest
      rtmutex: Remove duplicate rt_mutex_init()

----
 include/linux/rtmutex.h  | 12 +++---------
 include/linux/rwsem_rt.h |  1 -
 kernel/rt.c              | 37 ++++++++-----------------------------
 3 files changed, 11 insertions(+), 39 deletions(-)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/