From: Peter Zijlstra <peterz@infradead.org>
To: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Kees Cook <keescook@chromium.org>,
Eric Biggers <ebiggers@kernel.org>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Will Deacon <will@kernel.org>,
Elena Reshetova <elena.reshetova@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Anna-Maria Gleixner <anna-maria@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-sparse@vger.kernel.org
Subject: Re: [PATCH] locking/refcount: add sparse annotations to dec-and-lock functions
Date: Tue, 7 Jan 2020 10:29:35 +0100 [thread overview]
Message-ID: <20200107092935.GU2844@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200106175459.tjuhmdrsusax3s4z@ltop.local>
On Mon, Jan 06, 2020 at 06:54:59PM +0100, Luc Van Oostenryck wrote:
> On Mon, Jan 06, 2020 at 04:41:19PM +0100, Peter Zijlstra wrote:
> > extern bool spin_trylock(spinlock_t *lock) __attribute__((context(lock, 0, spin_trylock(lock));
>
> Well, allowing arbitrary conditions would be hard/impossible but you're
> only asking to have the *return value* as condition, right? That looks
> as reasonably feasible.
Just the return value would cover all the known cases yes. At the time
I might have been somewhat over ambitious..
> > Basically have sparse do a transform on its own expression tree and
> > inject the very same crud we now do manually. This avoids cluttering the
> > kernel tree with this nonsense.
>
> So, a call of a function declared with __acquires() or releases() is
> interpreted by Sparse as if the call is immediately followed by an
> increase or a decrease of the context. It wouldn't be very hard to
> add a new attribute (something like __cond_context) and let Sparse do
> as if a call to a function with such attribute is directly followed
> by a test of its return value and a corresponding change in the context.
> It would boil down to:
>
> extern bool spin_trylock(lock) __cond_context(lock);
>
> if (spin_trylock(lock)) {
> /* do crap */
> spin_unlock();
> }
>
> behaving like the following code currently would:
>
> extern bool spin_trylock(lock);
>
> if (spin_trylock(lock)) {
> __acquire(lock);
> /* do crap */
> spin_unlock();
> }
>
>
> Would something like this be satisfactory?
Very much so, Thanks!
next prev parent reply other threads:[~2020-01-07 9:29 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-26 15:29 [PATCH] locking/refcount: add sparse annotations to dec-and-lock functions Eric Biggers
2019-12-28 11:49 ` Peter Zijlstra
2019-12-28 20:15 ` Eric Biggers
2019-12-30 18:43 ` Kees Cook
2019-12-30 19:15 ` Eric Biggers
2019-12-30 19:32 ` Kees Cook
2019-12-30 23:38 ` Luc Van Oostenryck
2020-01-03 1:35 ` Linus Torvalds
2020-01-03 2:18 ` Luc Van Oostenryck
2020-01-03 12:55 ` Dan Carpenter
2020-01-06 15:41 ` Peter Zijlstra
2020-01-06 17:54 ` Luc Van Oostenryck
2020-01-07 9:29 ` Peter Zijlstra [this message]
2020-01-06 15:26 ` Peter Zijlstra
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