Messages in this thread | | | Date | Tue, 9 Mar 2021 11:40:16 +0100 | From | Greg KH <> | Subject | Re: [PATCH 4.4 1/3] futex: Change locking rules |
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On Tue, Mar 09, 2021 at 11:06:03AM +0800, Zheng Yejian wrote: > From: Peter Zijlstra <peterz@infradead.org> > > Currently futex-pi relies on hb->lock to serialize everything. But hb->lock > creates another set of problems, especially priority inversions on RT where > hb->lock becomes a rt_mutex itself. > > The rt_mutex::wait_lock is the most obvious protection for keeping the > futex user space value and the kernel internal pi_state in sync. > > Rework and document the locking so rt_mutex::wait_lock is held accross all > operations which modify the user space value and the pi state. > > This allows to invoke rt_mutex_unlock() (including deboost) without holding > hb->lock as a next step. > > Nothing yet relies on the new locking rules. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > Cc: juri.lelli@arm.com > Cc: bigeasy@linutronix.de > Cc: xlpang@redhat.com > Cc: rostedt@goodmis.org > Cc: mathieu.desnoyers@efficios.com > Cc: jdesfossez@efficios.com > Cc: dvhart@infradead.org > Cc: bristot@redhat.com > Link: http://lkml.kernel.org/r/20170322104151.751993333@infradead.org > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > [Lee: Back-ported in support of a previous futex back-port attempt] > Signed-off-by: Lee Jones <lee.jones@linaro.org> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> > --- > kernel/futex.c | 138 +++++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 112 insertions(+), 26 deletions(-)
What is the git commit id of this patch in Linus's tree?
thanks,
greg k-h
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