From: Sasha Levin <sashal@kernel.org> To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Thomas Gleixner <tglx@linutronix.de>, alsa-devel@alsa-project.org, Takashi Iwai <tiwai@suse.com>, Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.de>, Sasha Levin <sashal@kernel.org> Subject: [PATCH MANUALSEL 5.4 4/4] ALSA: pcsp: Make hrtimer forwarding more robust Date: Wed, 6 Oct 2021 07:12:50 -0400 [thread overview] Message-ID: <20211006111250.264294-4-sashal@kernel.org> (raw) In-Reply-To: <20211006111250.264294-1-sashal@kernel.org> From: Thomas Gleixner <tglx@linutronix.de> [ Upstream commit f2ff7147c6834f244b8ce636b12e71a3bd044629 ] The hrtimer callback pcsp_do_timer() prepares rearming of the timer with hrtimer_forward(). hrtimer_forward() is intended to provide a mechanism to forward the expiry time of the hrtimer by a multiple of the period argument so that the expiry time greater than the time provided in the 'now' argument. pcsp_do_timer() invokes hrtimer_forward() with the current timer expiry time as 'now' argument. That's providing a periodic timer expiry, but is not really robust when the timer callback is delayed so that the resulting new expiry time is already in the past which causes the callback to be invoked immediately again. If the timer is delayed then the back to back invocation is not really making it better than skipping the missed periods. Sound is distorted in any case. Use hrtimer_forward_now() which ensures that the next expiry is in the future. This prevents hogging the CPU in the timer expiry code and allows later on to remove hrtimer_forward() from the public interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: alsa-devel@alsa-project.org Cc: Takashi Iwai <tiwai@suse.com> Cc: Jaroslav Kysela <perex@perex.cz> Link: https://lore.kernel.org/r/20210923153339.623208460@linutronix.de Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <sashal@kernel.org> --- sound/drivers/pcsp/pcsp_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sound/drivers/pcsp/pcsp_lib.c b/sound/drivers/pcsp/pcsp_lib.c index 8f0f05bbc081..23a15d892e50 100644 --- a/sound/drivers/pcsp/pcsp_lib.c +++ b/sound/drivers/pcsp/pcsp_lib.c @@ -145,7 +145,7 @@ enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle) if (pointer_update) pcsp_pointer_update(chip); - hrtimer_forward(handle, hrtimer_get_expires(handle), ns_to_ktime(ns)); + hrtimer_forward_now(handle, ns_to_ktime(ns)); return HRTIMER_RESTART; } -- 2.33.0
WARNING: multiple messages have this Message-ID (diff)
From: Sasha Levin <sashal@kernel.org> To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sasha Levin <sashal@kernel.org>, alsa-devel@alsa-project.org, Takashi Iwai <tiwai@suse.de>, Takashi Iwai <tiwai@suse.com>, Thomas Gleixner <tglx@linutronix.de> Subject: [PATCH MANUALSEL 5.4 4/4] ALSA: pcsp: Make hrtimer forwarding more robust Date: Wed, 6 Oct 2021 07:12:50 -0400 [thread overview] Message-ID: <20211006111250.264294-4-sashal@kernel.org> (raw) In-Reply-To: <20211006111250.264294-1-sashal@kernel.org> From: Thomas Gleixner <tglx@linutronix.de> [ Upstream commit f2ff7147c6834f244b8ce636b12e71a3bd044629 ] The hrtimer callback pcsp_do_timer() prepares rearming of the timer with hrtimer_forward(). hrtimer_forward() is intended to provide a mechanism to forward the expiry time of the hrtimer by a multiple of the period argument so that the expiry time greater than the time provided in the 'now' argument. pcsp_do_timer() invokes hrtimer_forward() with the current timer expiry time as 'now' argument. That's providing a periodic timer expiry, but is not really robust when the timer callback is delayed so that the resulting new expiry time is already in the past which causes the callback to be invoked immediately again. If the timer is delayed then the back to back invocation is not really making it better than skipping the missed periods. Sound is distorted in any case. Use hrtimer_forward_now() which ensures that the next expiry is in the future. This prevents hogging the CPU in the timer expiry code and allows later on to remove hrtimer_forward() from the public interfaces. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: alsa-devel@alsa-project.org Cc: Takashi Iwai <tiwai@suse.com> Cc: Jaroslav Kysela <perex@perex.cz> Link: https://lore.kernel.org/r/20210923153339.623208460@linutronix.de Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <sashal@kernel.org> --- sound/drivers/pcsp/pcsp_lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sound/drivers/pcsp/pcsp_lib.c b/sound/drivers/pcsp/pcsp_lib.c index 8f0f05bbc081..23a15d892e50 100644 --- a/sound/drivers/pcsp/pcsp_lib.c +++ b/sound/drivers/pcsp/pcsp_lib.c @@ -145,7 +145,7 @@ enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle) if (pointer_update) pcsp_pointer_update(chip); - hrtimer_forward(handle, hrtimer_get_expires(handle), ns_to_ktime(ns)); + hrtimer_forward_now(handle, ns_to_ktime(ns)); return HRTIMER_RESTART; } -- 2.33.0
next prev parent reply other threads:[~2021-10-06 11:13 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-10-06 11:12 [PATCH MANUALSEL 5.4 1/4] KVM: x86: Handle SRCU initialization failure during page track init Sasha Levin 2021-10-06 11:12 ` [PATCH MANUALSEL 5.4 2/4] KVM: do not shrink halt_poll_ns below grow_start Sasha Levin 2021-10-06 11:23 ` Paolo Bonzini 2021-10-06 11:12 ` [PATCH MANUALSEL 5.4 3/4] kvm: x86: Add AMD PMU MSRs to msrs_to_save_all[] Sasha Levin 2021-10-06 11:23 ` Paolo Bonzini 2021-10-06 11:12 ` Sasha Levin [this message] 2021-10-06 11:12 ` [PATCH MANUALSEL 5.4 4/4] ALSA: pcsp: Make hrtimer forwarding more robust Sasha Levin 2021-10-06 11:23 ` [PATCH MANUALSEL 5.4 1/4] KVM: x86: Handle SRCU initialization failure during page track init Paolo Bonzini
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20211006111250.264294-4-sashal@kernel.org \ --to=sashal@kernel.org \ --cc=alsa-devel@alsa-project.org \ --cc=linux-kernel@vger.kernel.org \ --cc=perex@perex.cz \ --cc=stable@vger.kernel.org \ --cc=tglx@linutronix.de \ --cc=tiwai@suse.com \ --cc=tiwai@suse.de \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.