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Date: Wed, 17 Apr 2024 13:08:03 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Anna-Maria Behnsen <anna-maria@linutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	John Stultz <jstultz@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>, Stephen Boyd <sboyd@kernel.org>,
	Eric Biederman <ebiederm@xmission.com>
Subject: Re: [patch V2 07/50] posix-cpu-timers: Split up posix_cpu_timer_get()
Message-ID: <20240417110803.GA27840@redhat.com>
References: <20240416144438.GA17990@redhat.com>
 <87o7a8wdhr.fsf@somnus>
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User-Agent: Mutt/1.5.24 (2015-08-30)

On 04/17, Anna-Maria Behnsen wrote:
>
> Oleg Nesterov <oleg@redhat.com> writes:
>
> > On 04/11, Thomas Gleixner wrote:
> >>
> >> In preparation for addressing issues in the timer_get() and timer_set()
> >> functions of posix CPU timers.
> >
> > Cough... I must have missed something, but posix_cpu_timer_get()
> > doesn't look right with or without this trivial patch.
> >
> > It doesn't initialize itp->it_value if cpu_timer_getexpires() == 0,
> > this means that sys_timer_gettime() will copy the uninitialized
> > cur_setting->it_value on the stack to userspace?
>
> The initialization of itp is already done by the callsites.
> do_timer_settime() in posix-timers.c as well as do_cpu_nanosleep() in
> posix-cpu-timers.c execute a memset before calling
> posix_cpu_timer_get().

Indeed. Somehow I missed this memset(). Even if I tried to read the
simple do_timer_gettime/posix_cpu_timer_get functions several times ;)

Thanks for correcting me!

Oleg.