From patchwork Thu Oct 31 15:14:23 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nam Cao X-Patchwork-Id: 13859089 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 52871E6B249 for ; Fri, 1 Nov 2024 10:08:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0DDBD10E983; Fri, 1 Nov 2024 10:08:10 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; secure) header.d=linutronix.de header.i=@linutronix.de header.b="OXluRfXX"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="dt2VJX4y"; dkim-atps=neutral Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id ACFCE10E079 for ; Thu, 31 Oct 2024 15:15:07 +0000 (UTC) From: Nam Cao DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1730387706; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WU0OQTP8K3HetutHRTwicBx6y0d4IYn/PVSH3V3yCms=; b=OXluRfXXeLt3edtFXLjyirTIAAVAr321b79RwSZ5xO2L6K1wgbB2mhzmJLx0eY2Zkg2pwq SEGQjyPmuA2GPkXOEPTYSnrqeWjkn46s7qTS1Kn8Szcs5GlNi90jddFuYQZqS9AqErvjjt U5Rh0d3eHN6W86mu0F3HC2/1gJ5e9tXcgMUVmyBduzW1BfeuMDOO+t1+KNtJS0H8nSc5Q3 fQEQ+cymkgs9afOdBDrFAxlVTpehr7yNxzctx1L3AvLoH58GYGlE/zj4A4hGy1xhWdtV6c E0LFJ0Z/2MUV4MbkjYh+KerclqK8Xt0+SiEzdpp5L5gOUH+Q8URTcC6oqrt3WA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1730387706; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WU0OQTP8K3HetutHRTwicBx6y0d4IYn/PVSH3V3yCms=; b=dt2VJX4y7Oonm0lgdq0Gv3sFyvfZFvLpYDzXGfuTwJl/aXIr3aTCwH+cYXvOS8sOHvgwjQ mPal+9jnfMbIbCBg== To: Anna-Maria Behnsen , Frederic Weisbecker , Thomas Gleixner , Andreas Hindborg , Alice Ryhl , Miguel Ojeda , Kees Cook , linux-kernel@vger.kernel.org Cc: Jani Nikula , intel-gfx@lists.freedesktop.org, Sean Christopherson , Paolo Bonzini , x86@kernel.org, Jakub Kicinski , Kalle Valo , Jens Axboe , Christian Brauner , Peter Zijlstra , John Stultz , Nam Cao , Oliver Hartkopp Subject: [RESEND PATCH v2 09/19] hrtimers: Introduce hrtimer_update_function() Date: Thu, 31 Oct 2024 16:14:23 +0100 Message-Id: <20a937b0ae09ad54b5b6d86eabead7c570f1b72e.1730386209.git.namcao@linutronix.de> In-Reply-To: References: MIME-Version: 1.0 X-Mailman-Approved-At: Fri, 01 Nov 2024 10:08:01 +0000 X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Some users of hrtimer need to change the callback function after the initial setup. They write to hrtimer::function directly. That's not safe under all circumstances as the write is lockless and a concurrent timer expiry might end up using the wrong function pointer. Introduce hrtimer_update_function(), which also performs runtime checks whether it is safe to modify the callback. This allows to make hrtimer::function private once all users are converted. Signed-off-by: Nam Cao --- include/linux/hrtimer.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h index 48872a2b4071..6e026730e803 100644 --- a/include/linux/hrtimer.h +++ b/include/linux/hrtimer.h @@ -327,6 +327,28 @@ static inline int hrtimer_callback_running(struct hrtimer *timer) return timer->base->running == timer; } +/** + * hrtimer_update_function - Update the timer's callback function + * @timer: Timer to update + * @function: New callback function + * + * Only safe to call if the timer is not enqueued. Can be called in the callback function if the + * timer is not enqueued at the same time (see the comments above HRTIMER_STATE_ENQUEUED). + */ +static inline void hrtimer_update_function(struct hrtimer *timer, + enum hrtimer_restart (*function)(struct hrtimer *)) +{ + guard(raw_spinlock_irqsave)(&timer->base->cpu_base->lock); + + if (WARN_ON_ONCE(hrtimer_is_queued(timer))) + return; + + if (WARN_ON_ONCE(!function)) + return; + + timer->function = function; +} + /* Forward a hrtimer so it expires after now: */ extern u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);