Re: [PATCH] rcu: Remove redundant rcu_read_lock/unlock() in spin_lock critical sections
Waiman Long <[email protected]>
| Newsgroups | gmane.linux.kernel.aio.general,gmane.linux.kernel,gmane.linux.nfs,gmane.linux.file-systems,gmane.linux.kernel.lsm,gmane.linux.network,gmane.comp.freedesktop.xorg.drivers.intel,gmane.linux.acpi.devel,gmane.linux.kernel.cgroups |
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On 9/12/25 2:50 AM, pengdonglin wrote: > From: pengdonglin <[email protected]> > > When CONFIG_PREEMPT_RT is disabled, spin_lock*() operations implicitly > disable preemption, which provides RCU read-side protection. When > CONFIG_PREEMPT_RT is enabled, spin_lock*() implementations internally > manage RCU read-side critical sections. I have some doubt about your claim that disabling preemption provides RCU read-side protection. It is true for some flavors but probably not all. I do know that disabling interrupt will provide RCU read-side protection. So for spin_lock_irq*() calls, that is valid. I am not sure about spin_lock_bh(), maybe it applies there too. we need some RCU people to confirm. When CONFIG_PREEMPT_RT is enabled, rt_spin_lock/unlock() will call rcu_read_lock/_unlock() internally. So eliminating explicit rcu_read_lock/unlock() in critical sections should be fine. Cheers, Longman -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to [email protected]. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: <a href=mailto:"[email protected]">[email protected]</a>