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| author | Thomas Gleixner <tglx@linutronix.de> | 2020-05-21 22:05:17 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-06-11 15:15:04 +0200 |
| commit | 3eeec385848855c8109eb72b8b309078d5507968 (patch) | |
| tree | 8a5a5c65cf05151e9747dea2ce0d69c0da21b121 /arch/x86/include | |
| parent | 2ab70319bc1f79228da4dce7b9d604740c9beeef (diff) | |
| download | lwn-3eeec385848855c8109eb72b8b309078d5507968.tar.gz lwn-3eeec385848855c8109eb72b8b309078d5507968.zip | |
x86/entry: Provide idtentry_entry/exit_cond_rcu()
After a lengthy discussion [1] it turned out that RCU does not need a full
rcu_irq_enter/exit() when RCU is already watching. All it needs if
NOHZ_FULL is active is to check whether the tick needs to be restarted.
This allows to avoid a separate variant for the pagefault handler which
cannot invoke rcu_irq_enter() on a kernel pagefault which might sleep.
The cond_rcu argument is only temporary and will be removed once the
existing users of idtentry_enter/exit() have been cleaned up. After that
the code can be significantly simplified.
[ mingo: Simplified the control flow ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: "Paul E. McKenney" <paulmck@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: [1] https://lkml.kernel.org/r/20200515235125.628629605@linutronix.de
Link: https://lore.kernel.org/r/20200521202117.181397835@linutronix.de
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/idtentry.h | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index ce97478ffc40..a116b80662d4 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -7,8 +7,18 @@ #ifndef __ASSEMBLY__ -void idtentry_enter(struct pt_regs *regs); -void idtentry_exit(struct pt_regs *regs); +bool idtentry_enter_cond_rcu(struct pt_regs *regs, bool cond_rcu); +void idtentry_exit_cond_rcu(struct pt_regs *regs, bool rcu_exit); + +static __always_inline void idtentry_enter(struct pt_regs *regs) +{ + idtentry_enter_cond_rcu(regs, false); +} + +static __always_inline void idtentry_exit(struct pt_regs *regs) +{ + idtentry_exit_cond_rcu(regs, true); +} /** * DECLARE_IDTENTRY - Declare functions for simple IDT entry points |