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Date: Sun, 21 Sep 2025 19:35:54 -0400
From: Steven Rostedt <rostedt@kernel.org>
To: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
 bpf@vger.kernel.org, Masami Hiramatsu <mhiramat@kernel.org>, Mathieu
 Desnoyers <mathieu.desnoyers@efficios.com>, Peter Zijlstra
 <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>, Jiri Olsa
 <jolsa@kernel.org>, Arnaldo Carvalho de Melo <acme@kernel.org>, Namhyung
 Kim <namhyung@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Andrii
 Nakryiko <andrii@kernel.org>, Indu Bhagat <indu.bhagat@oracle.com>, "Jose
 E. Marchesi" <jemarch@gnu.org>, Beau Belgrave <beaub@linux.microsoft.com>,
 Jens Remus <jremus@linux.ibm.com>, Linus Torvalds
 <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>,
 Jens Axboe <axboe@kernel.dk>, Florian Weimer <fweimer@redhat.com>, Sam
 James <sam@gentoo.org>, "Paul E. McKenney" <paulmck@kernel.org>
Subject: Re: [PATCH v16 09/10] unwind deferred: Use SRCU
 unwind_deferred_task_work()
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References: <20250729182304.965835871@kernel.org>
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On Fri, 19 Sep 2025 17:31:15 -0700
Josh Poimboeuf <jpoimboe@kernel.org> wrote:

> On Tue, Jul 29, 2025 at 02:23:13PM -0400, Steven Rostedt wrote:
> > @@ -230,6 +232,14 @@ int unwind_deferred_request(struct unwind_work *work, u64 *cookie)
> >  	if (WARN_ON_ONCE(!CAN_USE_IN_NMI && in_nmi()))
> >  		return -EINVAL;
> >  
> > +	/* Do not allow cancelled works to request again */
> > +	bit = READ_ONCE(work->bit);
> > +	if (WARN_ON_ONCE(bit < 0))
> > +		return -EINVAL;  
> 
> The local 'bit' variable is unsigned long, so this will never be < 0.
> 
> Should be "bit == -1"?
> 

Yeah, that needs to be fixed. Thanks!

-- Steve