rcu: Don't redundantly disable irqs in rcu_irq_{enter,exit}()

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This commit replaces a local_irq_save()/local_irq_restore() pair with
a lockdep assertion that interrupts are already disabled.  This should
remove the corresponding overhead from the interrupt entry/exit fastpaths.

This change was inspired by the fact that Iftekhar Ahmed's mutation
testing showed that removing rcu_irq_enter()'s call to local_ird_restore()
had no effect, which might indicate that interrupts were always enabled
anyway.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

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This commit is contained in:

Paul E. McKenney 2015-10-31 00:59:01 -07:00

parent d117c8aa1d

commit 7c9906ca5e

5 changed files with 40 additions and 10 deletions

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4

include/linux/rcupdate.h

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8

include/linux/rcutiny.h

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include/linux/rcutree.h

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include/linux/tracepoint.h

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