Messages in this thread | | | Date | Wed, 22 Mar 2017 22:45:25 +0100 (CET) | From | Julia Lawall <> | Subject | Re: [PATCH v2 1/9] Coccinelle: locks: identify callers of spin_lock{,_irq,_irqsave}() in irqchip implementations |
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On Wed, 22 Mar 2017, Julia Cartwright wrote:
> On Wed, Mar 22, 2017 at 10:54:15AM +0100, Julia Lawall wrote: > > On Tue, 21 Mar 2017, Julia Cartwright wrote: > > > On PREEMPT_RT, the spinlock_t type becomes an object which sleeps under > > > contention. The codepaths used to support scheduling (irq dispatching, arch > > > code, the scheduler, timers) therefore must make use of the > > > raw_spin_lock{,_irq,_irqsave}() variations which preserve the non-sleeping > > > spinlock behavior. > > > > > > Because the irq_chip callbacks are invoked in the process of interrupt > > > dispatch, they cannot therefore make use of spin_lock_t type. Instead, the > > > usage of raw_spinlock_t is appropriate. > > > > > > Provide a spatch to identify (and attempt to patch) such problematic irqchip > > > implementations. > > > > > > Note to those generating patches using this spatch; in order to maintain > > > correct semantics w/ PREEMPT_RT, it is necessary to audit the > > > raw_spinlock_t-protected codepaths to ensure their execution is bounded and > > > minimal. This is a manual audit process. > > > > > > See commit 47b03ca903fb0 ("pinctrl: qcom: Use raw spinlock variants") as an > > > example of _one_ such instance, which fixed a real bug seen in the field. > > > > > > Cc: Thomas Gleixner <tglx@linutronix.de> > > > Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> > > > Cc: Linus Walleij <linus.walleij@linaro.org> > > > Signed-off-by: Julia Cartwright <julia@ni.com> > > > > Acked-by: Julia Lawall <julia.lawall@lip6.fr> > > Thanks, Julia. > > How do these semantic patches normally land? It looks like they quite a > few have gone through the kbuild tree, is this the norm?
Michal Marek takes care of them.
julia
> > Thanks, > Other Julia >
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