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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Michael Jeanson <mjeanson@efficios.com>,
	Jens Axboe <axboe@kernel.dk>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	x86@kernel.org, Sean Christopherson <seanjc@google.com>,
	Wei Liu <wei.liu@kernel.org>
Subject: [patch V6 08/31] rseq: Avoid CPU/MM CID updates when no event pending
Date: Mon, 27 Oct 2025 09:44:31 +0100 (CET)	[thread overview]
Message-ID: <20251027084306.462964916@linutronix.de> (raw)
In-Reply-To: 20251027084220.785525188@linutronix.de

There is no need to update these values unconditionally if there is no
event pending.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

---
 kernel/rseq.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -464,11 +464,12 @@ void __rseq_handle_notify_resume(struct
 		t->rseq_event_pending = false;
 	}
 
-	if (IS_ENABLED(CONFIG_DEBUG_RSEQ) || event) {
-		ret = rseq_ip_fixup(regs, event);
-		if (unlikely(ret < 0))
-			goto error;
-	}
+	if (!IS_ENABLED(CONFIG_DEBUG_RSEQ) && !event)
+		return;
+
+	ret = rseq_ip_fixup(regs, event);
+	if (unlikely(ret < 0))
+		goto error;
 
 	if (unlikely(rseq_update_cpu_node_id(t)))
 		goto error;





  parent reply	other threads:[~2025-10-27  8:44 UTC|newest]

Thread overview: 142+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-27  8:44 [patch V6 00/31] rseq: Optimize exit to user space Thomas Gleixner
2025-10-27  8:44 ` [patch V6 01/31] rseq: Avoid pointless evaluation in __rseq_notify_resume() Thomas Gleixner
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 02/31] rseq: Condense the inline stubs Thomas Gleixner
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 03/31] rseq: Move algorithm comment to top Thomas Gleixner
2025-10-29 10:24   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 04/31] rseq: Remove the ksig argument from rseq_handle_notify_resume() Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 05/31] rseq: Simplify registration Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 06/31] rseq: Simplify the event notification Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 07/31] rseq, virt: Retrigger RSEQ after vcpu_run() Thomas Gleixner
2025-10-28 15:08   ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` Thomas Gleixner [this message]
2025-10-29 10:23   ` [tip: core/rseq] rseq: Avoid CPU/MM CID updates when no event pending tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 09/31] rseq: Introduce struct rseq_data Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 10/31] entry: Cleanup header Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` [tip: core/rseq] entry: Clean up header tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 11/31] entry: Remove syscall_enter_from_user_mode_prepare() Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 12/31] entry: Inline irqentry_enter/exit_from/to_user_mode() Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 13/31] sched: Move MM CID related functions to sched.h Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 14/31] rseq: Cache CPU ID and MM CID values Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 15/31] rseq: Record interrupt from user space Thomas Gleixner
2025-10-28 15:26   ` Mathieu Desnoyers
2025-10-28 17:02     ` Thomas Gleixner
2025-10-28 17:53       ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 16/31] rseq: Provide tracepoint wrappers for inline code Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 17/31] rseq: Expose lightweight statistics in debugfs Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 18/31] rseq: Provide static branch for runtime debugging Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:44 ` [patch V6 19/31] rseq: Provide and use rseq_update_user_cs() Thomas Gleixner
2025-10-28 15:40   ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-10-29 16:04   ` [patch V6 19/31] " Steven Rostedt
2025-10-29 21:00     ` Thomas Gleixner
2025-10-29 21:53       ` Steven Rostedt
2025-11-03 14:47   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 20/31] rseq: Replace the original debug implementation Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-10-30 21:52   ` [patch V6 20/31] " Prakash Sangappa
2025-10-31 14:27     ` Thomas Gleixner
2025-11-03 14:47   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 21/31] rseq: Make exit debugging static branch based Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 22/31] rseq: Use static branch for syscall exit debug when GENERIC_IRQ_ENTRY=y Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 23/31] rseq: Provide and use rseq_set_ids() Thomas Gleixner
2025-10-28 15:47   ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 24/31] rseq: Separate the signal delivery path Thomas Gleixner
2025-10-28 15:51   ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 25/31] rseq: Rework the TIF_NOTIFY handler Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:17   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 26/31] rseq: Optimize event setting Thomas Gleixner
2025-10-28 15:57   ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:16   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 27/31] rseq: Implement fast path for exit to user Thomas Gleixner
2025-10-28 16:09   ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-10-29 16:28   ` [patch V6 27/31] " Steven Rostedt
2025-11-03 14:47   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-04  8:16   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 28/31] rseq: Switch to fast path processing on " Thomas Gleixner
2025-10-28 16:14   ` Mathieu Desnoyers
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:16   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 29/31] entry: Split up exit_to_user_mode_prepare() Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:16   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 30/31] rseq: Split up rseq_exit_to_user_mode() Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:16   ` tip-bot2 for Thomas Gleixner
2025-10-27  8:45 ` [patch V6 31/31] rseq: Switch to TIF_RSEQ if supported Thomas Gleixner
2025-10-29 10:23   ` [tip: core/rseq] " tip-bot2 for Thomas Gleixner
2025-11-03 14:47   ` tip-bot2 for Thomas Gleixner
2025-11-04  8:16   ` tip-bot2 for Thomas Gleixner
2025-10-29 10:23 ` [patch V6 00/31] rseq: Optimize exit to user space Peter Zijlstra

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