Messages in this thread Patch in this message | | | Date | Wed, 14 Dec 2022 09:01:35 -0500 | From | Steven Rostedt <> | Subject | [for-next][PATCH 2/8] x86/mm/kmmio: Remove redundant preempt_disable() |
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From: "Steven Rostedt (Google)" <rostedt@goodmis.org>
Now that kmmio uses rcu_read_lock_sched_notrace() there's no reason to call preempt_disable() as the read_lock_sched_notrace() already does that and is redundant.
This also removes the preempt_enable_no_resched() as the "no_resched()" portion was bogus as there's no reason to do that.
Link: https://lkml.kernel.org/r/20221212103703.7129cc5d@gandalf.local.home
Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> Cc: "x86@kernel.org" <x86@kernel.org> Cc: Karol Herbst <karolherbst@gmail.com> Cc: Pekka Paalanen <ppaalanen@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> --- arch/x86/mm/kmmio.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c index 853c49877c16..9f82019179e1 100644 --- a/arch/x86/mm/kmmio.c +++ b/arch/x86/mm/kmmio.c @@ -246,14 +246,13 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr) page_base &= page_level_mask(l); /* - * Preemption is now disabled to prevent process switch during - * single stepping. We can only handle one active kmmio trace + * Hold the RCU read lock over single stepping to avoid looking + * up the probe and kmmio_fault_page again. The rcu_read_lock_sched() + * also disables preemption and prevents process switch during + * the single stepping. We can only handle one active kmmio trace * per cpu, so ensure that we finish it before something else - * gets to run. We also hold the RCU read lock over single - * stepping to avoid looking up the probe and kmmio_fault_page - * again. + * gets to run. */ - preempt_disable(); rcu_read_lock_sched_notrace(); faultpage = get_kmmio_fault_page(page_base); @@ -324,7 +323,6 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr) no_kmmio: rcu_read_unlock_sched_notrace(); - preempt_enable_no_resched(); return ret; } @@ -364,7 +362,6 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs) ctx->active--; BUG_ON(ctx->active); rcu_read_unlock_sched_notrace(); - preempt_enable_no_resched(); /* * if somebody else is singlestepping across a probe point, flags -- 2.35.1
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