From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Kevin Hilman <khilman@kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>,
Magnus Damm <damm@opensource.se>,
Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
Linux PM list <linux-pm@vger.kernel.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] PM / Domains: Avoid infinite loops in attach/detach code
Date: Mon, 22 Jun 2015 09:30:20 +0200 [thread overview]
Message-ID: <CAMuHMdVoHM=K-hgide0-2gpuAZgTkEqLAzhCGuGLHtEMtpAgyw@mail.gmail.com> (raw)
In-Reply-To: <1434622954-26747-3-git-send-email-geert+renesas@glider.be>
On Thu, Jun 18, 2015 at 12:22 PM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
> If pm_genpd_{add,remove}_device() keeps on failing with -EAGAIN, we end
> up with an infinite loop in genpd_dev_pm_{at,de}tach().
>
> This may happen due to a genpd.prepared_count imbalance. This is a bug
> elsewhere, but it will result in a system lock up, possibly during
> reboot of an otherwise functioning system.
>
> To avoid this, put a limit on the maximum number of loop iterations,
> including a simple back-off mechanism. If the limit is reached, the
> operation will just fail. An error message is already printed.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> drivers/base/power/domain.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index cdd547bd67df8218..aa06f60b98b8af35 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2218,10 +2226,13 @@ int genpd_dev_pm_attach(struct device *dev)
>
> dev_dbg(dev, "adding to PM domain %s\n", pd->name);
>
> - while (1) {
> + for (i = 0; i < GENPD_RETRIES; i++) {
Sorry, there's a declaration of "i" missing.
> ret = pm_genpd_add_device(pd, dev);
> if (ret != -EAGAIN)
> break;
> +
> + if (i > GENPD_RETRIES / 2)
> + udelay(GENPD_DELAY_US);
> cond_resched();
> }
>
> --
> 1.9.1
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
Please read the FAQ at http://www.tux.org/lkml/
WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Kevin Hilman <khilman@kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>,
Magnus Damm <damm@opensource.se>,
Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
Linux PM list <linux-pm@vger.kernel.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] PM / Domains: Avoid infinite loops in attach/detach code
Date: Mon, 22 Jun 2015 09:30:20 +0200 [thread overview]
Message-ID: <CAMuHMdVoHM=K-hgide0-2gpuAZgTkEqLAzhCGuGLHtEMtpAgyw@mail.gmail.com> (raw)
In-Reply-To: <1434622954-26747-3-git-send-email-geert+renesas@glider.be>
On Thu, Jun 18, 2015 at 12:22 PM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
> If pm_genpd_{add,remove}_device() keeps on failing with -EAGAIN, we end
> up with an infinite loop in genpd_dev_pm_{at,de}tach().
>
> This may happen due to a genpd.prepared_count imbalance. This is a bug
> elsewhere, but it will result in a system lock up, possibly during
> reboot of an otherwise functioning system.
>
> To avoid this, put a limit on the maximum number of loop iterations,
> including a simple back-off mechanism. If the limit is reached, the
> operation will just fail. An error message is already printed.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> drivers/base/power/domain.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index cdd547bd67df8218..aa06f60b98b8af35 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2218,10 +2226,13 @@ int genpd_dev_pm_attach(struct device *dev)
>
> dev_dbg(dev, "adding to PM domain %s\n", pd->name);
>
> - while (1) {
> + for (i = 0; i < GENPD_RETRIES; i++) {
Sorry, there's a declaration of "i" missing.
> ret = pm_genpd_add_device(pd, dev);
> if (ret != -EAGAIN)
> break;
> +
> + if (i > GENPD_RETRIES / 2)
> + udelay(GENPD_DELAY_US);
> cond_resched();
> }
>
> --
> 1.9.1
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-pm" in
WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: linux-sh@vger.kernel.org
Subject: Re: [PATCH 2/2] PM / Domains: Avoid infinite loops in attach/detach code
Date: Mon, 22 Jun 2015 07:30:20 +0000 [thread overview]
Message-ID: <CAMuHMdVoHM=K-hgide0-2gpuAZgTkEqLAzhCGuGLHtEMtpAgyw@mail.gmail.com> (raw)
In-Reply-To: <1434622954-26747-3-git-send-email-geert+renesas@glider.be>
On Thu, Jun 18, 2015 at 12:22 PM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
> If pm_genpd_{add,remove}_device() keeps on failing with -EAGAIN, we end
> up with an infinite loop in genpd_dev_pm_{at,de}tach().
>
> This may happen due to a genpd.prepared_count imbalance. This is a bug
> elsewhere, but it will result in a system lock up, possibly during
> reboot of an otherwise functioning system.
>
> To avoid this, put a limit on the maximum number of loop iterations,
> including a simple back-off mechanism. If the limit is reached, the
> operation will just fail. An error message is already printed.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> drivers/base/power/domain.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
> index cdd547bd67df8218..aa06f60b98b8af35 100644
> --- a/drivers/base/power/domain.c
> +++ b/drivers/base/power/domain.c
> @@ -2218,10 +2226,13 @@ int genpd_dev_pm_attach(struct device *dev)
>
> dev_dbg(dev, "adding to PM domain %s\n", pd->name);
>
> - while (1) {
> + for (i = 0; i < GENPD_RETRIES; i++) {
Sorry, there's a declaration of "i" missing.
> ret = pm_genpd_add_device(pd, dev);
> if (ret != -EAGAIN)
> break;
> +
> + if (i > GENPD_RETRIES / 2)
> + udelay(GENPD_DELAY_US);
> cond_resched();
> }
>
> --
> 1.9.1
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-sh" in
next prev parent reply other threads:[~2015-06-22 7:30 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-18 10:22 [PATCH 0/2] PM / Domains: Infinite loop during reboot Geert Uytterhoeven
2015-06-18 10:22 ` Geert Uytterhoeven
2015-06-18 10:22 ` [PATCH 1/2] clocksource: sh_cmt: Only perform clocksource suspend/resume if enabled Geert Uytterhoeven
2015-06-18 10:22 ` Geert Uytterhoeven
2015-06-18 14:14 ` Laurent Pinchart
2015-06-18 14:14 ` Laurent Pinchart
2015-06-18 14:19 ` Geert Uytterhoeven
2015-06-18 14:19 ` Geert Uytterhoeven
2015-06-18 10:22 ` [PATCH 2/2] PM / Domains: Avoid infinite loops in attach/detach code Geert Uytterhoeven
2015-06-18 10:22 ` Geert Uytterhoeven
2015-06-22 7:30 ` Geert Uytterhoeven [this message]
2015-06-22 7:30 ` Geert Uytterhoeven
2015-06-22 7:30 ` Geert Uytterhoeven
2015-06-22 7:31 ` Geert Uytterhoeven
2015-06-22 7:31 ` Geert Uytterhoeven
2015-06-22 7:31 ` Geert Uytterhoeven
2015-06-22 23:41 ` Rafael J. Wysocki
2015-06-22 23:41 ` Rafael J. Wysocki
2015-06-22 23:41 ` Rafael J. Wysocki
2015-06-23 7:16 ` Geert Uytterhoeven
2015-06-23 7:16 ` Geert Uytterhoeven
2015-06-23 7:16 ` Geert Uytterhoeven
2015-06-23 12:50 ` Ulf Hansson
2015-06-23 12:50 ` Ulf Hansson
2015-06-23 13:20 ` Geert Uytterhoeven
2015-06-23 13:20 ` Geert Uytterhoeven
2015-06-23 13:38 ` Rafael J. Wysocki
2015-06-23 13:38 ` Rafael J. Wysocki
2015-06-23 13:45 ` Geert Uytterhoeven
2015-06-23 13:45 ` Geert Uytterhoeven
2015-06-24 8:33 ` Ulf Hansson
2015-06-24 8:33 ` Ulf Hansson
2015-06-24 8:35 ` Geert Uytterhoeven
2015-06-24 8:35 ` Geert Uytterhoeven
2015-06-24 13:48 ` Rafael J. Wysocki
2015-06-24 13:48 ` Rafael J. Wysocki
2015-06-24 13:44 ` Rafael J. Wysocki
2015-06-24 14:10 ` Rafael J. Wysocki
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