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From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	Davidlohr Bueso <dave@stgolabs.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	huang ying <huang.ying.caritas@gmail.com>,
	stable@vger.kernel.org
Subject: Re: [PATCH-tip v6 01/20] locking/rwsem: Prevent decrement of reader count before increment
Date: Sun, 28 Apr 2019 12:07:02 -0400	[thread overview]
Message-ID: <43b4250d-d9b5-a4b6-ee1b-d256ecddd105@redhat.com> (raw)
In-Reply-To: <20190428155755.14267-2-longman@redhat.com>

On 4/28/19 11:57 AM, Waiman Long wrote:
> During my rwsem testing, it was found that after a down_read(), the
> reader count may occasionally become 0 or even negative. Consequently,
> a writer may steal the lock at that time and execute with the reader
> in parallel thus breaking the mutual exclusion guarantee of the write
> lock. In other words, both readers and writer can become rwsem owners
> simultaneously.

I would like to have this particular patch merged in the next merge
window, if possible, so that I can backport it downstream.

Thanks,
Longman



  reply	other threads:[~2019-04-28 16:07 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-28 15:57 [PATCH-tip v6 00/20] locking/rwsem: Rwsem rearchitecture part 2 Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 01/20] locking/rwsem: Prevent decrement of reader count before increment Waiman Long
2019-04-28 16:07   ` Waiman Long [this message]
2019-04-28 17:41   ` Linus Torvalds
2019-04-28 17:59     ` Linus Torvalds
2019-04-28 19:40       ` Waiman Long
     [not found]   ` <20190428203916.E1AA6206A3@mail.kernel.org>
2019-04-28 20:47     ` Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 02/20] locking/rwsem: Make owner available even if !CONFIG_RWSEM_SPIN_ON_OWNER Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 03/20] locking/rwsem: Remove rwsem_wake() wakeup optimization Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 04/20] locking/rwsem: Implement a new locking scheme Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 05/20] locking/rwsem: Merge rwsem.h and rwsem-xadd.c into rwsem.c Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 06/20] locking/rwsem: Code cleanup after files merging Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 07/20] locking/rwsem: Make rwsem_spin_on_owner() return owner state Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 08/20] locking/rwsem: Implement lock handoff to prevent lock starvation Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 09/20] locking/rwsem: Always release wait_lock before waking up tasks Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 10/20] locking/rwsem: More optimal RT task handling of null owner Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 11/20] locking/rwsem: Wake up almost all readers in wait queue Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 12/20] locking/rwsem: Clarify usage of owner's nonspinaable bit Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 13/20] locking/rwsem: Enable readers spinning on writer Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 14/20] locking/rwsem: Enable time-based spinning on reader-owned rwsem Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 15/20] locking/rwsem: Adaptive disabling of reader optimistic spinning Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 16/20] locking/rwsem: Add more rwsem owner access helpers Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 17/20] locking/rwsem: Guard against making count negative Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 18/20] locking/rwsem: Merge owner into count on x86-64 Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 19/20] locking/rwsem: Remove redundant computation of writer lock word Waiman Long
2019-04-28 15:57 ` [PATCH-tip v6 20/20] locking/rwsem: Disable preemption in down_read*() if owner in count Waiman Long

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