Messages in this thread | | | Date | Wed, 11 Jul 2018 10:28:48 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH] cgroup: use irqsave in cgroup_rstat_flush_locked() |
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Hello, Sebastian.
On Wed, Jul 11, 2018 at 01:05:13PM +0200, Sebastian Andrzej Siewior wrote: > > > We at least used to do this in the kernel - manipulating irqsafe locks > > > with spin_lock/unlock() if the irq state is known, whether enabled or > > > disabled, and ISTR lockdep being smart enough to track actual irq > > > state to determine irq safety. Am I misremembering or is this > > > different on RT kernels? > > > > No, this is correct. So on !RT kernels the spin_lock_irq() disables > > interrupts and the raw_spin_lock() has the interrupts already disabled, > > everything is good. On RT kernels the spin_lock_irq() does not disable > > interrupts and the raw_spin_lock() acquires the lock with enabled > > interrupts and lockdep complains properly. > > lockdep sees the hardirq path via:
I feel weary about applying a patch which isn't needed in mainline, especially without annotations or at least comments. I suppose it may not be too common but this can't be the only place which needs this and using irqsave/restore spuriously in all those sites doesn't sound like a good solution. Is there any other way of handling this?
Thanks.
-- tejun
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