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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bjorn Helgaas <helgaas@kernel.org>, linux-pci@vger.kernel.org
Cc: Hari Vyas <hari.vyas@broadcom.com>,
	Ray Jui <ray.jui@broadcom.com>,
	Srinath Mannam <srinath.mannam@broadcom.com>,
	Guenter Roeck <linux@roeck-us.net>, Jens Axboe <axboe@kernel.dk>,
	Lukas Wunner <lukas@wunner.de>,
	Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
	Marta Rybczynska <mrybczyn@kalray.eu>,
	Pierre-Yves Kerbrat <pkerbrat@kalray.eu>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 2/6] pci: Set pci_dev->is_added before calling device_add
Date: Fri, 17 Aug 2018 14:57:40 +1000	[thread overview]
Message-ID: <8b11e45e969c8407bf063c4d515305eab2b0769d.camel@kernel.crashing.org> (raw)
In-Reply-To: <20180817044902.31420-3-benh@kernel.crashing.org>

s/device_add/device_attach .. ugh.

On Fri, 2018-08-17 at 14:48 +1000, Benjamin Herrenschmidt wrote:
> This re-fixes the bug reported by Hari Vyas <hari.vyas@broadcom.com>
> after my revert of his commit but in a much simpler way.
> 
> The main issues is that is_added was being set after the driver
> got bound and started, and thus setting it could race with other
> changes to struct pci_dev.
> 
> This fixes it by setting the flag first, which also has the
> advantage of matching the fact that we are clearing it *after*
> unbinding in the remove path, thus the flag is now symtetric
> and always set while the driver code is running.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>  drivers/pci/bus.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 35b7fc87eac5..48ae63673aa8 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -321,16 +321,16 @@ void pci_bus_add_device(struct pci_dev *dev)
>  	pci_proc_attach_device(dev);
>  	pci_bridge_d3_update(dev);
>  
> +	dev->is_added = 1;
>  	dev->match_driver = true;
>  	retval = device_attach(&dev->dev);
>  	if (retval < 0 && retval != -EPROBE_DEFER) {
> +		dev->is_added = 0;
>  		pci_warn(dev, "device attach failed (%d)\n", retval);
>  		pci_proc_detach_device(dev);
>  		pci_remove_sysfs_dev_files(dev);
>  		return;
>  	}
> -
> -	dev->is_added = 1;
>  }
>  EXPORT_SYMBOL_GPL(pci_bus_add_device);
>  


  reply	other threads:[~2018-08-17  4:58 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-17  4:48 [RFC PATCH 0/6] pci: Rework is_added race fix and address bridge enable races Benjamin Herrenschmidt
2018-08-17  4:48 ` [RFC PATCH 1/6] Revert "PCI: Fix is_added/is_busmaster race condition" Benjamin Herrenschmidt
2018-08-17  4:57   ` Benjamin Herrenschmidt
2018-08-17 15:44   ` Bjorn Helgaas
2018-08-18  3:24     ` Benjamin Herrenschmidt
2018-08-19  2:24       ` Bjorn Helgaas
2018-08-20  2:10         ` Benjamin Herrenschmidt
2018-08-20  6:25           ` Hari Vyas
2018-08-20 11:09             ` Benjamin Herrenschmidt
2018-08-20 11:43               ` Hari Vyas
2018-08-20  7:17           ` Lukas Wunner
2018-08-20 11:12             ` Benjamin Herrenschmidt
2018-08-17  4:48 ` [RFC PATCH 2/6] pci: Set pci_dev->is_added before calling device_add Benjamin Herrenschmidt
2018-08-17  4:57   ` Benjamin Herrenschmidt [this message]
2018-08-17 16:25   ` Bjorn Helgaas
2018-08-17 18:15     ` Lukas Wunner
2018-08-18  3:41       ` Benjamin Herrenschmidt
2018-08-18  3:28     ` Benjamin Herrenschmidt
2018-08-17  4:48 ` [RFC PATCH 3/6] pci: Remove priv_flags and use dev->error_state for "disconnected" status Benjamin Herrenschmidt
2018-08-17  5:13   ` [RFC PATCH v2 " Benjamin Herrenschmidt
2018-08-17  4:49 ` [RFC PATCH 4/6] pci: Add a mutex to pci_dev to protect device state Benjamin Herrenschmidt
2018-08-17  4:49 ` [RFC PATCH 5/6] pci: Protect the enable/disable state of pci_dev using the state mutex Benjamin Herrenschmidt
2018-08-17  8:09   ` Marta Rybczynska
2018-08-17  8:30     ` Benjamin Herrenschmidt
2018-08-17  9:00       ` Hari Vyas
2018-08-17  9:39         ` Benjamin Herrenschmidt
2018-08-17 10:10           ` Hari Vyas
2018-08-17 10:24             ` Benjamin Herrenschmidt
2018-08-17  4:49 ` [RFC PATCH 6/6] pci: Protect is_busmaster using the state lock Benjamin Herrenschmidt
2018-08-17  5:03 ` [RFC PATCH 0/6] pci: Rework is_added race fix and address bridge enable races Benjamin Herrenschmidt

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