linux-kernel - Re: [PATCH v8 01/12] drivers: base: Unified device connection lookup

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Message-ID: <20180320100412.GI11689@kuha.fi.intel.com>
Date:   Tue, 20 Mar 2018 12:04:12 +0200
From:   Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Mathias Nyman <mathias.nyman@...el.com>,
        Guenter Roeck <linux@...ck-us.net>, Jun Li <jun.li@....com>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH v8 01/12] drivers: base: Unified device connection lookup

On Tue, Mar 20, 2018 at 10:20:04AM +0100, Greg Kroah-Hartman wrote:
> On Wed, Mar 14, 2018 at 04:12:04PM +0300, Heikki Krogerus wrote:
> > Several frameworks - clk, gpio, phy, pmw, etc. - maintain
> > lookup tables for describing connections and provide custom
> > API for handling them. This introduces a single generic
> > lookup table and API for the connections.
> > 
> > The motivation for this commit is centralizing the
> > connection lookup, but the goal is to ultimately extract the
> > connection descriptions also from firmware by using the
> > fwnode_graph_* functions and other mechanisms that are
> > available.
> > 
> > Reviewed-by: Hans de Goede <hdegoede@...hat.com>
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> > Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> > ---
> > Changes in v8:
> > - No longer using rcu.
> 
> Ok, but then:
> 
> > +void *device_connection_find_match(struct device *dev, const char *con_id,
> > +			       void *data,
> > +			       void *(*match)(struct device_connection *con,
> > +					      int ep, void *data))
> > +{
> > +	const char *devname = dev_name(dev);
> > +	struct device_connection *con;
> > +	void *ret = NULL;
> > +	int ep;
> > +
> > +	if (!match)
> > +		return NULL;
> > +
> > +	mutex_lock(&devcon_lock);
> > +
> > +	list_for_each_entry_rcu(con, &devcon_list, list) {
> 
> _rcu calls everywhere :(
> 
> Did you send out the right version of this patch?
> 
> Also, further down you do:
> 
> > +#include <linux/platform_device.h>
> > +#include <linux/spi/spi.h>
> > +#include <linux/i2c.h>
> > +#include <linux/pci.h>
> 
> Eeek, #include in the middle of a file, not good.
> 
> > +
> > +static struct bus_type *generic_match_buses[] = {
> > +	&platform_bus_type,
> > +#ifdef CONFIG_PCI
> > +	&pci_bus_type,
> > +#endif
> > +#ifdef CONFIG_I2C
> > +	&i2c_bus_type,
> > +#endif
> > +#ifdef CONFIG_SPI_MASTER
> > +	&spi_bus_type,
> > +#endif
> > +	NULL,
> > +};
> 
> Can't you just declare the above as "extern" variables and not need the
> #include?  Yeah, checkpatch will complain, but it should be fine here as
> we really don't want the full .h files here (or need them.)

OK. I'll declare them as extern.

> > +void device_connection_remove(struct device_connection *con)
> > +{
> > +	mutex_lock(&devcon_lock);
> > +	list_del_rcu(&con->list);
> 
> See, rcu?

True. I'll send one more version.


Thanks,

-- 
heikki