From: Will Deacon <will@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
Ingo Molnar <mingo@kernel.org>,
Elena Reshetova <elena.reshetova@intel.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Hanjun Guo <guohanjun@huawei.com>,
Jan Glauber <jglauber@marvell.com>
Subject: Re: [PATCH 5/6] lib/refcount: Improve performance of generic REFCOUNT_FULL code
Date: Fri, 9 Aug 2019 16:38:29 +0100 [thread overview]
Message-ID: <20190809153829.qehhxxfwlwitmv74@willie-the-truck> (raw)
In-Reply-To: <20190802185514.GE2349@hirez.programming.kicks-ass.net>
On Fri, Aug 02, 2019 at 08:55:14PM +0200, Peter Zijlstra wrote:
> On Fri, Aug 02, 2019 at 11:09:59AM +0100, Will Deacon wrote:
> > static inline void refcount_add(int i, refcount_t *r)
> > {
> > + int old = atomic_fetch_add_relaxed(i, &r->refs);
> > +
> > + WARN_ONCE(!old, "refcount_t: addition on 0; use-after-free.\n");
> > + if (unlikely(old <= 0 || old + i <= 0)) {
> > + refcount_set(r, REFCOUNT_SATURATED);
> > + WARN_ONCE(1, "refcount_t: saturated; leaking memory.\n");
> > + }
> > }
>
> That will trigger both WARNs when !old.
Right you are. I'll make the second WARN_ONCE(old, ...);
Will
next prev parent reply other threads:[~2019-08-09 15:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 10:09 [PATCH 0/6] Rework REFCOUNT_FULL using atomic_fetch_* operations Will Deacon
2019-08-02 10:09 ` [PATCH 1/6] lib/refcount: Define constants for saturation and max refcount values Will Deacon
2019-08-02 10:09 ` [PATCH 2/6] lib/refcount: Ensure integer operands are treated as signed Will Deacon
2019-08-02 10:09 ` [PATCH 3/6] lib/refcount: Remove unused refcount_*_checked() variants Will Deacon
2019-08-02 10:09 ` [PATCH 4/6] lib/refcount: Move bulk of REFCOUNT_FULL implementation into header Will Deacon
2019-08-02 18:52 ` Peter Zijlstra
2019-08-03 2:23 ` Kees Cook
2019-08-09 16:04 ` Will Deacon
2019-08-12 18:08 ` Kees Cook
2019-08-02 10:09 ` [PATCH 5/6] lib/refcount: Improve performance of generic REFCOUNT_FULL code Will Deacon
2019-08-02 18:55 ` Peter Zijlstra
2019-08-09 15:38 ` Will Deacon [this message]
2019-08-02 10:10 ` [PATCH 6/6] lib/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions Will Deacon
2019-08-02 18:49 ` [PATCH 0/6] Rework REFCOUNT_FULL using atomic_fetch_* operations Peter Zijlstra
2019-08-09 15:34 ` Will Deacon
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