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From: Greg KH <gregkh@linuxfoundation.org>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	davem@davemloft.net, Dave Ertman <david.m.ertman@intel.com>,
	netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	nhorman@redhat.com, sassmann@redhat.com, parav@mellanox.com,
	galpress@amazon.com, selvin.xavier@broadcom.com,
	sriharsha.basavapatna@broadcom.com, benve@cisco.com,
	bharat@chelsio.com, xavier.huwei@huawei.com,
	yishaih@mellanox.com, leonro@mellanox.com, mkalderon@marvell.com,
	aditr@vmware.com, Kiran Patil <kiran.patil@intel.com>,
	Andrew Bowers <andrewx.bowers@intel.com>
Subject: Re: [RFC PATCH v4 01/25] virtual-bus: Implementation of Virtual Bus
Date: Fri, 14 Feb 2020 19:53:46 -0500
Message-ID: <20200215005346.GB32359@kroah.com> (raw)
In-Reply-To: <20200215000154.GZ31668@ziepe.ca>

On Fri, Feb 14, 2020 at 08:01:54PM -0400, Jason Gunthorpe wrote:
> On Fri, Feb 14, 2020 at 03:43:41PM -0500, Greg KH wrote:
> > On Fri, Feb 14, 2020 at 04:34:55PM -0400, Jason Gunthorpe wrote:
> > > On Fri, Feb 14, 2020 at 09:02:40AM -0800, Greg KH wrote:
> > > > > +/**
> > > > > + * virtbus_dev_register - add a virtual bus device
> > > > > + * @vdev: virtual bus device to add
> > > > > + */
> > > > > +int virtbus_dev_register(struct virtbus_device *vdev)
> > > > > +{
> > > > > +	int ret;
> > > > > +
> > > > > +	if (!vdev->release) {
> > > > > +		dev_err(&vdev->dev, "virtbus_device .release callback NULL\n");
> > > > 
> > > > "virtbus_device MUST have a .release callback that does something!\n" 
> > > > 
> > > > > +		return -EINVAL;
> > > > > +	}
> > > > > +
> > > > > +	device_initialize(&vdev->dev);
> > > > > +
> > > > > +	vdev->dev.bus = &virtual_bus_type;
> > > > > +	vdev->dev.release = virtbus_dev_release;
> > > > > +	/* All device IDs are automatically allocated */
> > > > > +	ret = ida_simple_get(&virtbus_dev_ida, 0, 0, GFP_KERNEL);
> > > > > +	if (ret < 0) {
> > > > > +		dev_err(&vdev->dev, "get IDA idx for virtbus device failed!\n");
> > > > > +		put_device(&vdev->dev);
> > > > 
> > > > If you allocate the number before device_initialize(), no need to call
> > > > put_device().  Just a minor thing, no big deal.
> > > 
> > > If *_regster does put_device on error then it must always do
> > > put_device on any error, for instance the above return -EINVAL with
> > > no put_device leaks memory.
> > 
> > That's why I said to move the ida_simple_get() call to before
> > device_initialize() is called.  Once device_initialize() is called, you
> > HAVE to call put_device().
> 
> Yes put_device() becomes mandatory, but if the ida is moved up then
> the caller doesn't know how to handle an error:
> 
>    if (ida_simple_get() < 0)
>        return -EINVAL; // caller must do kfree
>    device_initialize();
>    if (device_register())
>        return -EINVAL // caller must do put_device

No, call put_device() before returning.

Ugh, anyway, this is all trivial stuff, the code is correct as-is,
nevermind.  If it bugs me enough, I'll send a patch that ends up
removing one more line of code than adding :)

greg k-h

  reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 19:13 [RFC PATCH v4 00/25] Intel Wired LAN/RDMA Driver Updates 2020-02-11 Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 01/25] virtual-bus: Implementation of Virtual Bus Jeff Kirsher
2020-02-14 17:02   ` Greg KH
2020-02-14 20:34     ` Jason Gunthorpe
2020-02-14 20:43       ` Greg KH
2020-02-15  0:01         ` Jason Gunthorpe
2020-02-15  0:53           ` Greg KH [this message]
2020-02-14 20:45       ` Greg KH
2020-02-20 18:55         ` Ertman, David M
2020-02-20 19:27           ` Jason Gunthorpe
2020-02-14 21:22   ` Parav Pandit
2020-02-15  0:08   ` Jason Gunthorpe
2020-02-12 19:14 ` [RFC PATCH v4 02/25] ice: Create and register virtual bus for RDMA Jeff Kirsher
2020-02-14 20:39   ` Jason Gunthorpe
2020-02-20 18:48     ` Ertman, David M
2020-02-20 20:58       ` Jason Gunthorpe
2020-02-12 19:14 ` [RFC PATCH v4 03/25] ice: Complete RDMA peer registration Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 04/25] ice: Support resource allocation requests Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 05/25] ice: Enable event notifications Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 06/25] ice: Allow reset operations Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 07/25] ice: Pass through communications to VF Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 08/25] i40e: Move client header location Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 09/25] i40e: Register a virtbus device to provide RDMA Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 10/25] RDMA/irdma: Add driver framework definitions Jeff Kirsher
2020-02-14 22:13   ` Parav Pandit
2020-02-18 20:42     ` Saleem, Shiraz
2020-02-20 22:24       ` Parav Pandit
2020-02-20 23:06         ` Jason Gunthorpe
2020-02-21 17:01         ` Saleem, Shiraz
2020-02-21 17:23           ` Parav Pandit
2020-02-21 18:04             ` Jason Gunthorpe
2020-02-12 19:14 ` [RFC PATCH v4 11/25] RDMA/irdma: Implement device initialization definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 12/25] RDMA/irdma: Implement HW Admin Queue OPs Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 13/25] RDMA/irdma: Add HMC backing store setup functions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 14/25] RDMA/irdma: Add privileged UDA queue implementation Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 15/25] RDMA/irdma: Add QoS definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 16/25] RDMA/irdma: Add connection manager Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 17/25] RDMA/irdma: Add PBLE resource manager Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 18/25] RDMA/irdma: Implement device supported verb APIs Jeff Kirsher
2020-02-14 14:54   ` Jason Gunthorpe
2020-02-14 15:49     ` Andrew Boyer
2020-02-14 16:45       ` Jason Gunthorpe
2020-02-18 20:43     ` Saleem, Shiraz
2020-02-12 19:14 ` [RFC PATCH v4 19/25] RDMA/irdma: Add RoCEv2 UD OP support Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 20/25] RDMA/irdma: Add user/kernel shared libraries Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 21/25] RDMA/irdma: Add miscellaneous utility definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 22/25] RDMA/irdma: Add dynamic tracing for CM Jeff Kirsher
2020-02-14 14:53   ` Jason Gunthorpe
2020-02-18 20:43     ` Saleem, Shiraz
2020-02-12 19:14 ` [RFC PATCH v4 23/25] RDMA/irdma: Add ABI definitions Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 24/25] RDMA: Add irdma Kconfig/Makefile and remove i40iw Jeff Kirsher
2020-02-12 19:14 ` [RFC PATCH v4 25/25] RDMA/irdma: Update MAINTAINERS file Jeff Kirsher

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