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From:   Oleksandr Natalenko <oleksandr@natalenko.name>
To:     greybus-dev@lists.linaro.org, linux-i2c@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-staging@lists.linux.dev,
        linux-usb@vger.kernel.org, netdev@vger.kernel.org,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Alex Elder <elder@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Hans de Goede <hdegoede@redhat.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hovold <johan@kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Rui Miguel Silva <rmfrfs@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        UNGLinuxDriver@microchip.com, Wolfram Sang <wsa@kernel.org>,
        Woojung Huh <woojung.huh@microchip.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Michael Below <below@judiz.de>,
        Salvatore Bonaccorso <carnil@debian.org>
Subject: Re: [PATCH 2/7] i2c: core: Use generic_handle_irq_safe() in i2c_handle_smbus_host_notify().
Date:   Thu, 27 Jan 2022 15:41:24 +0100
Message-ID: <4929165.31r3eYUQgx@natalenko.name>
In-Reply-To: <20220127113303.3012207-3-bigeasy@linutronix.de>
References: <20220127113303.3012207-1-bigeasy@linutronix.de> <20220127113303.3012207-3-bigeasy@linutronix.de>
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Hello.

On =C4=8Dtvrtek 27. ledna 2022 12:32:58 CET Sebastian Andrzej Siewior wrote:
> The i2c-i801 driver invokes i2c_handle_smbus_host_notify() from his
> interrupt service routine. On PREEMPT_RT i2c-i801's handler is forced
> threaded with enabled interrupts which leads to a warning by
> handle_irq_event_percpu() assuming that irq_default_primary_handler()
> enabled interrupts.
>=20
> i2c-i801's interrupt handler can't be made non-threaded because the
> interrupt line is shared with other devices.
>=20
> Use generic_handle_irq_safe() which can invoked with disabled and enabled
> interrupts.
>=20
> Reported-by: Michael Below <below@judiz.de>
> Link: https://bugs.debian.org/1002537
> Cc: Salvatore Bonaccorso <carnil@debian.org>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  drivers/i2c/i2c-core-base.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 2c59dd748a49f..3f9e5303b6163 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -1424,7 +1424,7 @@ int i2c_handle_smbus_host_notify(struct i2c_adapter=
 *adap, unsigned short addr)
>  	if (irq <=3D 0)
>  		return -ENXIO;
> =20
> -	generic_handle_irq(irq);
> +	generic_handle_irq_safe(irq);
> =20
>  	return 0;
>  }
>=20

Reviewed-by: Oleksandr Natalenko <oleksandr@natalenko.name>

Worth linking [1] [2] and [3] as well maybe?

[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1873673
[2] https://bugzilla.kernel.org/show_bug.cgi?id=3D202453
[3] https://lore.kernel.org/lkml/20201204201930.vtvitsq6xcftjj3o@spock.loca=
ldomain/

=2D-=20
Oleksandr Natalenko (post-factum)