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    SubjectRe: [PATCH 5/5] drivers/i2c/busses/i2c-nuc900.c: Convert release_resource to release_region/release_mem_region
    On Mon, 14 Feb 2011, Marek Vasut wrote:

    > On Sunday 13 February 2011 13:12:12 Julia Lawall wrote:
    > > Request_region should be used with release_region, not release_resource.
    > >
    > > The result of request_mem_region is no longer stored. Instead the field
    > > ioarea is used to store a pointer to the resource structure that contains
    > > the start address. This is the information that is needed later in
    > > nuc900_i2c_remove to release the region. The field ioarea is also printed
    > > in some debugging code.
    > >
    > > The semantic match that finds this problem is as follows:
    > > (http://coccinelle.lip6.fr/)
    > >
    > > // <smpl>
    > > @@
    > > expression x,E;
    > > @@
    > > (
    > > *x = request_region(...)
    > >
    > > *x = request_mem_region(...)
    > > )
    > > ... when != release_region(x)
    > > when != x = E
    > > * release_resource(x);
    > > // </smpl>
    > >
    > > Signed-off-by: Julia Lawall <julia@diku.dk>
    > >
    > > ---
    > > Not compiled due to incompatible architecture.
    > >
    > > drivers/i2c/busses/i2c-nuc900.c | 13 +++++--------
    > > 1 file changed, 5 insertions(+), 8 deletions(-)
    > >
    > > diff --git a/drivers/i2c/busses/i2c-nuc900.c
    > > b/drivers/i2c/busses/i2c-nuc900.c index 7243426..97b16b7 100644
    > > --- a/drivers/i2c/busses/i2c-nuc900.c
    > > +++ b/drivers/i2c/busses/i2c-nuc900.c
    > > @@ -568,15 +568,13 @@ static int __devinit nuc900_i2c_probe(struct
    > > platform_device *pdev) goto err_clk;
    > > }
    > >
    > > - i2c->ioarea = request_mem_region(res->start, resource_size(res),
    > > - pdev->name);
    > > -
    > > - if (i2c->ioarea == NULL) {
    > > + if (!request_mem_region(res->start, resource_size(res), pdev->name)) {
    >
    > I prefer the original version here -- it's clearer and also, doesn't the new
    > version violate line-over-80 principle ?

    The line ends before column 80.

    I'm not sure that the result of request_mem_region is the proper argment
    to give to release_region. In any case, all of the other calls to
    request_mem_region that do use release_region do not use the return value.
    They just test it directly as I have done here.

    julia

    > > dev_err(&pdev->dev, "cannot request IO\n");
    > > ret = -ENXIO;
    > > goto err_clk;
    > > }
    > >
    > > + i2c->ioarea = res;
    > > i2c->regs = ioremap(res->start, resource_size(res));
    > >
    > > if (i2c->regs == NULL) {
    > > @@ -645,8 +643,7 @@ static int __devinit nuc900_i2c_probe(struct
    > > platform_device *pdev) iounmap(i2c->regs);
    > >
    > > err_ioarea:
    > > - release_resource(i2c->ioarea);
    > > - kfree(i2c->ioarea);
    > > + release_mem_region(res->start, resource_size(res));
    > >
    > > err_clk:
    > > clk_disable(i2c->clk);
    > > @@ -665,6 +662,7 @@ static int __devinit nuc900_i2c_probe(struct
    > > platform_device *pdev) static int __devexit nuc900_i2c_remove(struct
    > > platform_device *pdev) {
    > > struct nuc900_i2c *i2c = platform_get_drvdata(pdev);
    > > + struct resource *res = i2c->ioarea;
    >
    > No need for this ...
    > >
    > > i2c_del_adapter(&i2c->adap);
    > > free_irq(i2c->irq, i2c);
    > > @@ -674,8 +672,7 @@ static int __devexit nuc900_i2c_remove(struct
    > > platform_device *pdev)
    > >
    > > iounmap(i2c->regs);
    > >
    > > - release_resource(i2c->ioarea);
    > > - kfree(i2c->ioarea);
    >
    > ... the i2c pointer is still available here, why introducing struct resource
    > *res. release_mem_region() looks like a sane change to me though.
    >
    > > + release_mem_region(res->start, resource_size(res));
    > > kfree(i2c);
    > >
    > > return 0;
    > --
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